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415703 Cognitive Neuropsychology
Week 8:
Main Objectives:
Review and Summary: Neurological Examination, clinical cases and neuropsychological interpretation te p etat o
1.
2.
3.
4.
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired. It can be used both as a screening tool and as an investigative tool, the former of which when examining the patient when there is no expected neurological deficit and the latter of which when examining a patient where you do expect to find abnormalities. If a problem is found either in an investigative or screening process then further tests can be carried out to focus on a particular aspect of the nervous system (such as lumbar punctures and blood tests).
lumbar punctures
and blood tests)
Generally a neurological examination is focused towards finding out if there are lesions in the central
and peripheral nervous systems or whether there is another diffuse process which is troubling the patient. Once the patient has been thoroughly tested, it is then the role of the physician to determine whether or not these findings combine to form a recognizable medical syndrome such as Parkinson's disease or motor neurone disease. Finally, it is the role of the physician to find the etiological reasons for why such a problem has occurred, for example finding if the problem was due to inflammation or congenital.
The Neurological Examination
The Neuropsychological tests
Clinical cases and neuropsychological interpretation
Review and Summary
4.1 1 Organization
1 Organization of the nervous system
Organization of the nervous system
of the nervous system
4.2 2 Functional Brain Imaging
Functional Brain Imaging
4.3 3 Sensory
Sensory––Motor Systems and Cortical Functions
4.4 4 Cerebral cortexes and lobe functions: Occipital, Cerebral cortexes and lobe functions: Occipital, Parietal, Temporal and Frontal lobes
Patient’s History
A patient's history is the most important part of a neurological examination and must be performed before any other procedures unless impossible (i.e. the patient is unconscious). Certain aspects of a patients history will become more important depending upon the complaint issued. Important factors to be taken in the medical history include:
1. Time of onset, duration and associated symptoms (e.g. is the complaint chronic or acute)
2. Age, gender and occupation of the patient 3. Handedness (right or left handed) 4. Past medical history 5. Drug history 6. Family and social history
6. Family and social history Handedness is important in establishing the area of the brain important for language (as almost all right‐handed people have a left hemisphere which is responsible for language). As patients answer questions, it is important to gain an idea of the complaint thoroughly and understand its time course. Understanding the patient's neurological state at the time of questioning is important, and an idea should be obtained of how competent the patient is with various tasks and their level of impairment in carrying out these tasks. The interval of a complaint is important as it can help aid the diagnosis. For example, vascular disorders occur very frequently over minutes and hours, whereas congenital disorders occur over a matter of years.
Carrying out a 'general' examination is just as important as the neurological exam as it may lead to clues to the etiology of the complaint. This is shown by cases of cerebral metastases
where the initial complaint was of a mass in the breast.
List of tests
Specific tests in a neurological examination include:
1. Mental Status Examination
2. Cranial Nerves Examination
3. Motor System Examination
4. Deep tendon Reflexes
5 Sensory System Examination
5. Sensory System Examination
6. Cerebellum Examination (Motor Coordination and Gaits)
7. Higher Brain Functions
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Romberg's test or the Romberg maneuver is a Interpretation
The results of the examination are taken together to anatomically identify the lesion. This may be diffuse (e.g. neuromuscular diseases, encephalopathy) or highly specific (e.g. abnormal sensation in one dermatome due to compression of a specific spinal nerve by a tumor deposit). A differential diagnosis may then be constructed that takes into account the patient's background (e.g. previous cancer, autoimmune diathesis) and present findings to include the most likely causes. Examinations are aimed at ruling out the most clinically significant causes (even if relatively rare, e.g. brain tumor in a patient with subtle word finding abnormalities but no increased intracranial pressure) and ruling in the most likely causes
test used by doctors in a neurological examination, and also as a test for drunken driving. The exam is based on the premise that a person requires at least two of the three following senses to maintain balanced while standing:
Proprioception (the ability to know one's body in space); Vestibular function (the ability to know one's head position in space); and Vision (which can be used to monitor [and adjust for] changes in body position).
A patient who has a problem with proprioception can still maintain balance by using vestibular function and vision. In the Romberg test, the patient is stood up and asked to close his eyes. A loss of balance is interpreted as a positive Romberg sign.
The Romberg test is a test of the body's sense of positioning (proprioception), which requires healthy functioning of the dorsal
(proprioception), which requires healthy functioning of the dorsal columns of the spinal cord,[1].
The Romberg test is used to investigate the cause of loss of motor coordination (ataxia). A positive Romberg test suggests that the ataxia is sensory in nature, that is, depending on loss of proprioception. If a patient is ataxic and Romberg's test is not positive, it suggests that ataxia is cerebellar in nature, that is, depending on localized cerebellar dysfunction instead.
It is used as an indicator for possible alcohol or drug impaired driving and neurological decompression sickness.[2][3] When used to test impaired driving, the test is performed with the subject estimating 30 seconds in his head. This is used to gauge the subject's internal clock and can be an indicator of stimulant or depressant use. The test was named after the German neurologist Moritz Heinrich Romberg[1] (1795‐1873), who also gave his name to Parry‐
Romberg syndrome and Howship‐Romberg sign.
Procedure for Romberg's test or the Romberg maneuver
Ask the subject to stand erect with feet together and eyes closed. Stand close by as a precaution in order to stop the person from falling over and hurting himself or herself. Watch the movement of the body in relation to a perpendicular object behind the subject (corner of the room, door, window etc). A positive sign is noted when a swaying, sometimes irregular swaying and even toppling over occurs. The essential feature is that the patient becomes more unsteady with eyes closed.
The essential features of the test are as follows:
1. the subject stands with feet together, eyes open and hands by the sides. 2. the subject closes the eyes while the examiner observes for a full minute. Because the examiner is trying to elicit whether the patient falls when the eyes are
Because the examiner is trying to elicit whether the patient falls when the eyes are closed, it is advisable to stand ready to catch the falling patient. For large subjects, a strong assistant is recommended.
Romberg's test is positive if the patient sways or falls while the patient's eyes are closed. Patients with a positive result are said to demonstrate Romberg's sign or Rombergism. They can also be described as Romberg's positive. The basis of this test is that balance comes from the combination of several neurological systems, namely proprioception, vestibular input, and vision. If any two of these systems are working the person should be able to demonstrate a fair degree of balance. The key to the test is that vision is taken away by asking the patient to close their eyes. This leaves only two of the three systems remaining and if there is a vestibular disorder (labyrinthine) or a sensory disorder (proprioceptive dysfunction) the patient will become much more imbalanced.
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Maintaining balance while standing in the stationary position relies on intact sensory pathways, sensorimotor integration centers and motor pathways.
The main sensory inputs are:
1. Joint position sense (proprioception), carried in the dorsal columns of the spinal cord; 2. Vision
3. Vestibular apparatus Crucially, the brain can obtain sufficient information to maintain balance if any two of the three systems are intact.
Sensorimotor integration is carried out by the cerebellum and by the dorsal column‐medial lemniscus tract. The motor pathway is the corticospinal
(pyramidal) tract and the medial and lateral vestibular tracts.
The first stage of the test (standing with the eyes open), demonstrates that at least two of the three sensory pathways is intact, and that sensorimotor
integration and the motor pathway are functioning.
In the second stage, the visual pathway is removed by closing the eyes, known as a "sharpened Romberg". If the proprioceptive and vestibular pathways are intact, balance will be maintained. But if proprioception is defective, two of the sensory inputs will be absent and the patient will sway then fall.
The sharpened Romberg does have an early learning effect that will plateau between the third and fourth attempts.
Neurological Examination Videos
And Neurological case examples
http://library.med.utah.edu/neurologicexam/cases/html_case01/case01_history.html
Positive Romberg
Romberg's test is positive in conditions causing sensory ataxia such as:
Conditions affecting the dorsal columns of the spinal cord, such as tabes
dorsalis (neurosyphilis), in which it was first described. Conditions affecting the sensory nerves (sensory peripheral neuropathies), such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Friedreich's Ataxia
Romberg and cerebellar function
Romberg'ss test is not a test of cerebellar
Romberg
test is not a test of cerebellar function, as it is commonly function as it is commonly
misconstrued. Patients with cerebellar ataxia will, generally, be unable to balance even with the eyes open;[5] therefore, the test cannot proceed beyond the first step and no patient with cerebellar ataxia can correctly be described as Romberg's positive. Rather, Romberg's test is a test of the proprioception
receptors and pathways function. A positive Romberg's test has been shown to be 90% sensitive for lumbar spinal stenosis.[
A case begins with a Case History in which preliminary information about the patient and any signs and symptoms are presented.
The Neurological Examination follows the
Examination follows the Case History. You can choose the order and the parts of the neurological examination that you would like to view by clicking on the icon that represents that part of the exam. After completing the exam, you advance to listing your abnormal findings. You use the supplied Checklist of Findings and compare your choices with that of an expert's. You are now ready to begin the process of anatomical localization.
From a list of the structures, you choose the brain structure(s) those you think are damaged for the case. Your choices are compared to an expert's, and the lesion is highlighted on the image.
You start to Localize the Level(s) of the Lesion by selecting from the level of the neuroaxis. Your choices include:
1. Supratentorial
2. Infratentorial
3. Spinal Cord 4. Peripheral Nerve System 5. Multiple Levels
You have now arrived at an anatomical diagnosis, the first essential step in making a neurological diagnosis.
Finally, in the Case Discussion, you review the case and the thought processes used to reach the diagnosis. Neuroimaging studies, if available, are shown as part of the case discussion. 3
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Case No. 01: The Upset Office Manager
The patient is a 48‐year‐old woman who was in her usual state of good health when she experienced nausea and vomiting after being emotionally upset. After 3 hours of nausea and vomiting she had the sudden onset of numbness of her left arm which progressed to include her left leg and the left side of her face.
She was taken to the Emergency Room. Upon arrival she complained that she had double vision especially when she looked to the right. When she covered her right eye the most peripheral image (the
When she covered her right eye, the most peripheral image (the ghost image) would disappear. She also noticed that when she looked in the mirror the right side of her face didn’t move. Over the next 2 months, the double vision resolved, but the rest of her complaints have persisted
http://library.med.utah.edu/neurologicexam/cases/html_case01/case01_history.html
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This 48‐year‐old woman had the sudden onset and rapid progression of her symptoms, which is the temporal profile of an acute vascular event or a stroke. Risk factors for stroke include hypertension, cardiac disease, diabetes mellitus, smoking as well as coagulation and autoimmune disorders. This patient had none of these risk factors.
One of the first steps in localizing the occluded vessel in a stroke is to decide if the vessel is in the anterior or posterior arterial circulation of the brain. Most strokes occur in the anterior or carotid circulation because most of the brain’s blood supply is supplied by the carotids. Although strokes in the posterior or vertebrobasilar circulation are less common, this patient’s cranial nerve findings suggest an infarct in the brainstem and not the carotid territory. By history and examination there are 3 findings that indicate possible cranial nerve involvement Her history of diplopia indicates a right 6th (abducens) cranial nerve deficit involvement. Her history of diplopia
indicates a right 6th (abducens) cranial nerve deficit
(remember the most peripheral image is the false image and covering the right eye eliminated this image) and by examination she has a right 7th (facial) cranial nerve deficit. To explain these two deficits one has to localize the lesion in the caudal pons in the area of the 6th and 7th cranial nerve nuclei or the pathway of the nerves at this level. To explain the sensory findings on the left side of her face, we could postulate either a left spinal trigeminal tract lesion or it could be from a lesion affecting the axons of the 2nd order neurons which have crossed over to the right side of the pons and are ascending in the ventral trigeminothalamic tract. The left spinal trigeminal tract lesion hypothesis is unattractive, because it would mean a second lesion. In the pons, the ascending ventral trigeminothalamic tract is near the facial nucleus, so a lesion affecting this tract is the likely explanation. The last finding that we have to account for anatomically is the sensory deficit on the left side of the body. We first have to decide if the deficit is from a lesion in the DC‐ML system or the spinothalamic (ALS) system. For this patient, pain and temperature are affected while vibratory, position sense, and discriminatory sensation are preserved, which indicates that the spinothalamic tract is involved but the DC‐ML system is spared. Recall that the axons from the second order neurons that form the spinothalamic tract cross immediately in the spinal cord and ascend in the anterolateral spinal cord and the lateral part of the brainstem. In the pons, the spinothalamic tract, carrying pain and temperature for the left side of the body, is adjacent to the facial motor nucleus. So we could explain all the clinical findings for this case by a lesion in the
So we could explain all the clinical findings for this case by a lesion in the mediolateral part of the right lower pons most likely caused by occlusion of one of the short circumferential branches of the basilar artery. It is not a paramedian lesion because the patient has no findings referable to the corticospinal tracts and the medial lemniscus. It is also not a far lateral lesion because there are no right‐
sided spinal trigeminal tract, vestibular, or cerebellar findings. An MRI scan of the patient done 6 months after her stroke shows a small residual lesion in the area of the right abducens nucleus. This imaging finding doesn’t cover the entire anatomical area where we know there has to be disease, but it does support the hypothesis that there has been a small stroke in the area where we localized her lesion based on her clinical findings
Review and Summary:
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415703 Cognitive Neuropsychology
Week 1:
Introduction to Neuropsychology
Neuropsychology,,
and the Organization of the
Nervous System.
System.
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
Main Objectives:
1. What is Neuropsychology (for education)?
2. What are neuropsychological disorders?
3. New Approaches and tools in neuropsychological disorders.
4. What are neuropsychological assessment?
py
g
5. What is the Organization of the nervous system?
6. What are the structure and functions of specific human brain areas?
Neuropsychology (Brain and Mind)
Neuropsychology studies the structure and function of the
brain related to specific psychological (mental) processes
and behaviors.
The term neuropsychology has been applied to lesion studies in humans and
animals. It has also been applied to efforts to record electrical activity from
individual cells (or groups of cells) in higher primates (including some studies
of human patients)
patients). It is scientific in its approach and shares an information
processing view of the mind with cognitive psychology and cognitive
neuroscience.
In practice neuropsychologists tend to work in clinical settings (involved
in assessing or treating patients with neuropsychological problems –
see clinical neuropsychology), forensic settings or industry (often as
consultants where neuropsychological knowledge is applied to product design
or in the management of pharmaceutical clinical-trials research for drugs that
might have a potential impact on CNS functioning).
Posner, M. I. & DiGirolamo,
DiGirolamo, G. J. (2000
2000)) Cognitive Neuroscience:
Neuroscience:Origins and Promise,Psychological
Promise,Psychological Bulletin, 126
126::6, 873‐
873‐889
From Wikipedia, the free encyclopedia
Divisions of the Nervous System
Cellular components of the nervous tissue
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Spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that
extends from the brain (the medulla oblongata specifically). The brain and spinal cord
together make up the central nervous system. The spinal cord begins at the Occipital bone
and extends down to the space between the first and second lumbar vertebrae; it does
not extend the entire length of the vertebral column. It is around 45 cm (18 in) in men and
around 43 cm (17 in) long in women. Also, the spinal cord has a varying width, ranging
from 1/2 inch thick in the cervical and lumbar regions to 1/4 inch thick in the thoracic
area. The enclosing bony vertebral column protects the relatively shorter spinal cord.
The spinal cord functions primarily in the transmission of neural signals between the brain
and
d the
th restt off the
th body
b d but
b t also
l contains
t i neurall circuits
i it that
th t can independently
i d
d tl control
t l
numerous reflexes and central pattern generators. The spinal cord has three major
functions:: 1. Serve as a conduit for motor information, which travels down the spinal cord
functions
cord..
2. Serve as a conduit for sensory information, which travels up the spinal cord
cord.. 3. Serve as
a center for coordinating certain reflexes
reflexes..
The spinal cord is the main pathway for information connecting the brain and peripheral
nervous system. The length of the spinal cord is much shorter than the length of the bony
spinal column. The human spinal cord extends from the medulla oblongata and continues
through the conus medullaris near the first lumbar vertebra, terminating in a fibrous
extension known as the filum terminale
Somatosensory system
Dermatome
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Autonomic nervous system (ANS or visceral
nervous system) is the part of the peripheral nervous system that acts
Autonomic N
Autonomic Nervous S
ervous System (ANS) and autonomic reflexes
as a control system functioning largely below the level of consciousness, and
controls visceral functions. The ANS affects heart rate, digestion, respiration rate,
salivation, perspiration, diameter of the pupils, micturition (urination), and sexual
arousal. Whereas most of its actions are involuntary, some, such as breathing,
work in tandem with the conscious mind.
It is classically divided into two subsystems: the parasympathetic nervous system
(PSNS) and sympathetic nervous system (SNS). Relatively recently, a third
subsystem of neurons that have been named 'non
'non‐‐adrenergic and non‐
non‐cholinergic'
neurons (because they use nitric oxide as a neurotransmitter) have been
described and found to be integral in autonomic function, particularly in the gut
and the lungs.
With regard to function, the ANS is usually divided into sensory (afferent) and
motor (efferent) subsystems. Within these systems, however, there are inhibitory
and excitatory synapses between neurons.
The enteric nervous system is sometimes considered part of the autonomic
nervous system, and sometimes considered an independent system.
Alongside the other two components of the autonomic nervous system, the sympathetic
nervous system aids in the control of most of the body's internal organs. Stress—as in the
flight‐or‐fight response—is thought to counteract the parasympathetic system, which
generally works to promote maintenance of the body at rest. In truth, the functions of
both the parasympathetic and sympathetic nervous systems are not so straightforward,
but this is a useful rule of thumb.
There are two kinds of neurons involved in the transmission of any signal through the
sympathetic system; pre‐ and post‐ ganglionic. The shorter preganglionic neurons originate
from the thoracolumbar region of the spinal cord (levels T1 ‐ L2, specifically) and travel to
a ganglion, often one of the paravertebral ganglia, where they synapse with a
postganglionic neuron. From there, the long postganglionic neurons extend across most of
y
the body.
At the synapses within the ganglia, preganglionic neurons release acetylcholine, a
neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic
neurons. In response to this stimulus postganglionic neurons ‐ with two important
exceptions ‐ release norepinephrine, which activates adrenergic receptors on the
peripheral target tissues. The activation of target tissue receptors causes the effects
associated with the sympathetic system.
The two exceptions mentioned above are postganglionic neurons innervating sweat
glands—which release acetylcholine for the activation of muscarinic receptors ‐ and the
adrenal medulla. The adrenal medulla develops in tandem with the sympathetic nervous
system, and acts as a modified sympathetic ganglion: synapses occur between pre‐ and
post‐ ganglionic neurons within it, but the post ganglionic neurons do not leave the
medulla; instead they directly release norepinephrine and epinephrine into the blood.
Sympathetic nervous system
Sympathetic and parasympathetic systems
Parasympathetic nervous system
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Control of blood vessels
Brainstem (or brain stem)
stem)
Control of pupil
is the posterior part of the brain,
adjoining and structurally continuous with the spinal cord. The brain stem
provides the main motor and sensory innervation to the face and neck via the
cranial nerves. Though small, this is an extremely important part of the brain as
the nerve connections of the motor and sensory systems from the main part of
the brain to the rest of the body pass through the brain stem. This includes the
corticospinal tract (motor), the posterior column‐medial lemniscus pathway (fine
touch, vibration sensation and proprioception) and the spinothalamic tract (pain,
temperature, itch and crude touch). The brain stem also plays an important role
in the regulation of cardiac and respiratory function. It also regulates the central
nervous system, and is pivotal in maintaining consciousness and regulating the
sleep cycle.
Brainstem is made up of 1. medulla oblongata (myelencephalon), 2. pons (part of
metencephalon), 3. midbrain (mesencephalon), and 4. diencephalon
There are three main functions of the brain stem:
Mid‐‐sagittal view of the Mid
adult human brain
1. The first is its role in conduction. That is, all information relayed from the body
to the cerebrum and cerebellum and vice versa, must traverse the brain stem.
The ascending pathways coming from the body to the brain are the sensory
pathways, and include the spinothalamic tract for pain and temperature
sensation and the dorsal column, fasciculus gracilis, and cuneatus for touch,
proprioception, and pressure sensation (both of the body). (The facial sensations
have simiar pathways, and will travel in the spinothalamic tract and the medial
lemniscus also). Descending tracts are upper motor neurons destined to synapse
on lower
l
motor neurons in
i the
h ventrall horn
h
and
d intermediate
i
di
h
horn
off the
h spinal
i l
cord. In addition, there are upper motor neurons that originate in the brain
stem's vestibular, red, tectal, and reticular nuclei, which also descend and synapse
in the spinal cord.
2. The cranial nerves 3‐12 emerge from the brain stem.
3. The brain stem has integrative functions (it is involved in cardiovascular system
control, respiratory control, pain sensitivity control, alertness, awareness, and
consciousness). Thus, brain stem damage is a very serious and often life‐
threatening problem.
Brainstem and cerebellum
Ventral view
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12 Cranial nerves:
12 Cranial nerves:
1.
2.
3.
4.
5.
6.
7
7.
8.
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Auditory and Vestibular
9. Glossopharyngeal
10. Vagus
11. Spinal Accessory
12. Hypoglossal
Control of respiration
Cardiovascular controls
Long tracts of Sensory and Motor Systems
1. Pathways in spinal cord and brainstem
2. Functions
3. Clinical correlates, signs and symptoms
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Cerebellum
Vestibular and Cerebellum
The cerebellum
(Latin for little brain) is a region of the
brain that plays an important role in motor control. It is also involved
in some cognitive functions such as attention and language, and
probably in some emotional functions such as regulating fear and
pleasure responses. Its movement‐related functions are the most
clearly understood, however. The cerebellum does not initiate
movement, but it contributes to coordination
coordination,, precision, and
accurate timing
timing.. It receives input from sensory systems and from
other parts of the brain and spinal cord, and integrates these inputs
to fine tune motor activity. Because of this fine‐tuning function,
damage to the cerebellum does not cause paralysis, but instead
produces disorders in fine movement, equilibrium, posture, and
motor learning
In addition to its direct role in motor control and coordination
coordination, the
cerebellum also is necessary for several types of motor learning, the
most notable one being learning to adjust to changes in
sensorimotor relationships
relationships..
The Human Cerebellum:
Cerebellar Functions (Classical Functions):
Co‐ordination of Movements
Stabilizing of Vestibulo‐ocular Reflex (VOR)
Patterned Skilled Movements
Coordination of Eye Movements
Vermis Lobule VI‐‐‐‐Saccadic Eye Movements
Flocculus‐‐‐‐ Visual Tracking
Equilibrium, Gait and Postural Controls
Controls of Autonomic Functions (Cardiovascular)
Immune Functions (?)
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The Human Cerebellum:
The Human Cerebellum:
Clinical Correlates on the Human Cerebellum:
Flocculo‐Nodular Lobe:
Disturbed Equilibrium or Balance
Tendency to fall on the side of the lesion
Extensor hypotonia
“R li
“Reeling or Drunken” Gait or Posture
D k ”G i
P
Deviation Nystagmus
Clinical Correlates on the Human Cerebellum:
1. Eye in mid‐line Position: fine nystagmus, quick phase toward lesion side
2. Eye fixed 10 – 30 degree away from the lesion side:
No nystagmus
3. Eye fixed beyond 30 degree away from the lesion side
nystagmus with quick phase away from lesion side
4. Eye shift beyond midline toward the lesion side
gross nystagnus, quick phase toward lesion side
Anterior Lobe & Vermis:
Hypotonia (Reduced muscle tone)
Hyporeflexia
Ataxia (Incoordination of Movements)
Asynergia, Dysynergia (lack of synergy)
Intention or Action Tremor (Atelokinesia)
Asthenia (Weakness of muscular strength)
Rebounded Phenomenon
Cerebellar Hemisphere & Dentate Nucleus:
Dysmetria (Pass pointing)
Dysdiadochokinesia or Adiadochokinesia
(can not perform rapid alternating movements)
Disturbed Voluntary Skilled movements
Disturbed Speech (Drunken Speech) 13
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The Principles of Motor Controls of Movements:
Dysmetria of thought
1. The central nervous system (CNS) has to choose the right group of muscles by selecting specific pathways.
2. The CNS must give the right amount of excitatory or inhibitory inputs (“Command”) to specific motoneuron pools
3. The excitatory and inhibitory commands must be regulated “Spatially” and “Temporally”.
p
y
p
y
4. The CNS must regulate the following parameters:
‐ force
‐displacement (distance)
‐ velocity, acceleration or deceleration Pyramidal System:
Cortico‐spinal tracts
Cortico‐
UMN Lesions (Pyramidal Syndrome)
A. Paralyze movements in hemiplegic, quadriplegic, or paraplegic distribution, not individual muscles
B. Atrophy of disuse only (late and slight)
C. Hyperactive MSRs Clonus
D. Clasp‐knife spasticity E. Absent abdominal and cremasteric reflexes
F. Extensor toe sign (Babinski sign)
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Plantar Flexion
Dorsi‐ Flexion
LMN Lesions
A. Paralyze individual muscles or sets of muscles in root or peripheral nerve distribution
B. Atrophy of denervation (early and severe
C. Fasciculations and fibrillations
Fasciculations and fibrillations
D. Hypoactive or absent MSRs Hypotonia
UMN = upper motoneuron; LMN = lower motoneuron; MSRs = muscle stretch reflexes
Disease of the basal ganglion:
Parkinson’s disease
Basal ganglion and Extrapyramidal
System
Chorea and Huntington’s Chorea
Athetosis and Athetoid
Sydenham’s Chorea
Hemibalism .. Lesion of subthalamic nucleus
Dystonia, Torticolis, Wilson’s disease (Copper)
Kern icterus (Bilirubin stain)
Motor control system
Motor homonculus
(Maps)
Parkinson’s disease:
Akinesia or Hypokiesia
cog wheel rigidity
Resting Tremor
Degeneration of Dopaminergic neurons in Pars Compacta of the Substantia Nigra
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Control of body movements, visceral organs, behavior and emotion
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small
nuclei with a variety of functions. One of the most important functions of the
hypothalamus is to link the nervous system to the endocrine system via the
pituitary gland (hypophysis).
The hypothalamus is located below the thalamus, just above the brain stem. In
the terminology of neuroanatomy, it forms the ventral part of the diencephalon.
All vertebrate brains contain a hypothalamus. In humans, it is roughly the size of
an almond.
The hypothalamus is responsible for certain metabolic processes and other
activities of the autonomic nervous system. It synthesizes and secretes certain
neurohormones, often called hypothalamic‐releasing hormones, and these in
turn stimulate or inhibit the secretion of pituitary hormones. The hypothalamus
controls body temperature, hunger, thirst, fatigue, sleep, and circadian cycles.
Controls of body temperature
Controls of food intake and body weight
Endocrine and Hormonal controls
Controls of kidney functions 16
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Limbic
System
Controls of emotion and motivation
ti ti
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections. Its function includes relaying sensation, spatial sense, and motor signals to the cerebral cortex, along with the regulation of consciousness sleep and
along with the regulation of consciousness, sleep, and alertness. The thalamus surrounds the third ventricle. It is the main product of the embryonic diencephalon
The thalamus has multiple functions.
functions.
Thalamus and Cerebral cortex
It is generally believed to act as a relay between a
variety of subcortical areas and the cerebral cortex. In particular, every sensory system (with the
exception of the olfactory system) includes a thalamic nucleus that receives sensory signals and sends
them to the associated primary cortical area. For the visual system, for example, inputs from the retina
are sent to the lateral geniculate nucleus of the thalamus, which in turn projects to the primary visual
cortex (area V1) in the occipital lobe. The thalamus is believed to both process sensory information as
well as relaying it—each of the primary sensory relay areas receives strong "back projections" from
the cerebral cortex. Similarly the medial geniculate nucleus acts as a key auditory relay between the
inferior colliculus of the midbrain and the primary auditory cortex, and the ventral posterior nucleus is
a key somatosensory relay, which sends touch and proprioceptive information to the primary
somatosensory cortex.
The thalamus also plays an important role in regulating states of sleep and wakefulness.[4] Thalamic
nuclei have strong reciprocal connections with the cerebral cortex, forming thalamo
thalamo‐cortico‐thalamic
cortico thalamic
circuits that are believed to be involved with consciousness. The thalamus plays a major role in
regulating arousal, the level of awareness, and activity. Damage to the thalamus can lead to
permanent coma.
Many different functions are linked to various regions of the thalamus. This is the case for many of the
sensory systems (except for the olfactory system), such as the auditory, somatic, visceral, gustatory
and visual systems where localized lesions provoke specific sensory deficits. A major role of the
thalamus is devoted to "motor" systems. This has been and continues to be a subject of interest for
investigators. VIm, the relay of cerebellar afferences, is the target of stereotactians particularly for the
improvement of tremor. The role of the thalamus in the more anterior pallidal and nigral territories in
the basal ganglia system disturbances is recognized but still poorly understood. The contribution of the
thalamus to vestibular or to tectal functions is almost ignored. The thalamus has been thought of as a
"relay" that simply forwards signals to the cerebral cortex. Newer research suggests that thalamic
function is more selective
The cerebral cortex
Cerebral cortex in different areas is a sheet of neural tissue that is outermost to the
cerebrum of the mammalian brain. It plays a key role in memory, attention,
perceptual awareness, thought, language, and consciousness. It is constituted of
up to six horizontal layers, each of which has a different composition in terms of
neurons and connectivity. The human cerebral cortex is 2–4 mm (0.08–
0.16 inches) thick.
In preserved brains, it has a gray color, hence the name "gray matter". In contrast
to gray matter that is formed from neurons and their unmyelinated fibers, the
white matter below them is formed predominantly by myelinated axons
interconnecting neurons in different regions of the cerebral cortex with each
other and neurons in other parts of the central nervous system.
system
The surface of the cerebral cortex is folded in large mammals, such that more
than two‐thirds of it in the human brain is buried in the grooves, called "sulci".
The phylogenetically most recent part of the cerebral cortex, the neocortex (also
called isocortex), is differentiated into six horizontal layers; the more ancient part
of the cerebral cortex, the hippocampus (also called archicortex), has at most
three cellular layers, and is divided into subfields. Neurons in various layers
connect vertically to form small microcircuits, called columns. Different
neocortical architectonic fields are distinguished upon variations in the thickness
of these layers, their predominant cell type and other factors such as
neurochemical markers.
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Functional brain mapping
แผนที่การทํางานของสมอง (Brain Mapping)
Brain Mapping)
Broadmann’ ’ s Areas
Broadmann
s Areas
Brodmann’s area
is a region of the cerebral cortex defined based on
its cytoarchitectonics, or organization of cells
Brodmann areas were originally defined and numbered by the German neurologist
Korbinian Brodmann based on the cytoarchitecture organisation of neurons he
observed in the cerebral cortex using the Nissl stain. Brodmann published his maps
of cortical areas in humans, monkeys, and other species in 1909, along with many
other findings and observations regarding the general cell types and laminar
organization of the mammalian cortex. (The same Brodmann area number in
different species does not necessarily indicate homologous areas.)
Broadmann’s area #
A more detailed and verifiable cortical map have since been published by Constantin von
Economo and Georg N.
N Koskinas which greatly improves the quality of the cytoarchitectonic
classifications.
Many of the areas Brodmann defined based solely on their neuronal organization have since
been correlated closely to diverse cortical functions. For example, Brodmann areas 1, 2 and
3 are the primary somatosensory cortex; area 4 is the primary motor cortex; area 17 is the
primary visual cortex; and areas 41 and 42 correspond closely to primary auditory cortex.
Higher order functions of the association cortical areas are also consistently localized to the
same Brodmann areas by neurophysiological, functional imaging, and other methods (e.g.,
the consistent localization of Broca's speech and language area to the left Brodmann areas
44 and 45). However, functional imaging can only identify the approximate localization of
brain activations in terms of Brodmann areas since their actual boundaries in any individual
brain requires its histological examination.
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Brodmann areas for human & non‐
areas for human & non‐human primates
Brodmann’s areas 3D
map: Lateral Surface
map: Medial Surface
Brodmann areas for human & non‐
areas for human & non‐human primates
Paul MacLean M.D.
Paul MacLean’s
Triune Brain
The Reptilian Brain : Core brainstem
The Paleomammalian Brain : the limbic system
The Neomammalian Brain : neocortex and neocerebellum
สมองส่ วนแรก คือ สมองของสัตว์ เลือ้ ยคลาน (Reptilian Brain)
เป็ นสมองที่มนุษย์เราได้ รับมรดกตกทอดมาจากสัตว์เลื ้อยคลานยุคดึกดําบรรพ์ อยูภ่ ายใต้
อิทธิพลของพันธุกรรม 90 – 95 % และเจริ ญเติบโตในระหว่างที่อยูใ่ นครรภ์มารดาเป็ น
ส่วนใหญ่ เมื่อเกิดมาแล้ วสิ่งแวดล้ อมมีอิทธิพลต่อสมองส่วนนี ้น้ อยมาก มันจะถูกปั จจัย
ทางพันธุกรรมกําหนดมาเลยว่าเป็ นสมองคน หรื อสมองสัตว์และมีโครงสร้ างและการ
ทํางานอย่างไร สมองส่วนนี ้ควบคุมการทํางานของอวัยวะต่างในร่ างกายโดยอัตโนมัติ
และพฤติกรรมที่เป็ นสัญชาติญาณของสิ่งมีชีวิตที่มีมาโดยกําเนิดโดยการกําหนดของ
พันธุกรรม ได้ มรดกโดยตรงมาจากพ่อแม่ พ่อแม่เป็ นอย่างไรลูกจะได้ มรดกตกทอดมาเป็ น
อย่างนันเลย
อยางนนเลย
้
Reptilian Brain มลกษณะเปนแกนอยู
Reptilian Brain
มีลกั ษณะเป็ นแกนอย่ตอนในสดของสมองเป็
อนในสุดของสมองเปนสวนของ
นส่วนของ
ก้ านสมองและสมองตอนกลาง สมองส่วนที่หนึง่ นี ้เป็ นสมองส่วนที่ทําให้ มนุษย์มีสญ
ั ชาติ
ญาณของการอยูร่ อด การกิน การขับถ่าย การสืบพันธ์ เริ่ มสร้ างขึ ้นตังแต่
้ ขณะที่ทารกอยูใ่ น
ครรภ์มารดา ในวันที่คลอดนันสมองส่
้
วนนี ้สามารถทํางานได้ ราว 99 % และเติบโตสมบูรณ์
พร้ อมทํางานเต็มที่ในช่วงขวบปี แรก ถ้ าสมองส่วนแรกนี ้ไม่สามารถทํางานได้ ดีทารกก็ไม่
อาจมีชีวิตอยูร่ อดได้ เพราะมันไปควบคุมการเต้ นของหัวใจ การหายใจ ระบบขับถ่าย การ
กินการอยู่ การตื่น การนอนหลับทุกอย่างหมดเลย ในช่วงสองขวบปี แรก พ่อแม่ และผู้เลี ้ยง
ดูเด็กจะสอนเด็กให้ สามารถควบคุมร่ างกาย ควบคุมการกินอยู่ ควบคุมการขับถ่าย และ
สร้ างนิสยั ต่างๆที่เหมาะสมกับการอยูร่ อดในสังคม
สมองส่ วนที่สอง คือ สมองสัตว์ เลีย้ งลูกด้ วยนมยุคโบราณ
(Paleomammalian Brain หรือ Limbic System) เป็ นสมองส่วนที่
มนุษย์เราได้ รับมรดกตกทอดมาจากสัตว์เลี ้ยงลูกด้ วยนมยุคโบราณ สมองส่วนนี ้จะเริ่ ม
สร้ างและเจริ ญเติบโตเมื่อทารกอยูใ่ นครรภ์มารดาได้ ราว ๆ หกเดือน Limbic Systemจะมีลกั ษณะคล้ ายวงแหวนที่ห้ มุ รอบๆสมองส่วนแรกซึง่ มีลกั ษณะเป็ นแกน
เอาไว้ หน้ าที่ของสมองส่วนนี ้ก็คือ ทําให้ ทารกเกิดความจําเกี่ยวกับเหตุการณ์และสถานที่
(Episodic or Spatiotemporal Memory) โดยเฉพาะความจําที่เกี่ยวกับ
ใบหน้ าแม่ จํากลิ่นแม่ได้ ทําให้ มนุษย์ร้ ูจกั ตัวเอง (“Self”) และพัฒนาให้ มีความรู้สกึ
(Feeling)และการแสดงออกทางอารมณ์ตา่ ง ๆ มันจะเป็ นตัวที่ทําให้ ทารกร้ องไห้ โยเย
เรี ยกร้ องความสนใจ แสดงอารมณ์ความรู้สกึ เวลา ดีใจ-เสียใจ ชอบ-ไม่ชอบ พอใจ-ไม่
พอใจ สมองส่วนที่สองนี ้ทําให้ มนุษย์เราแตกต่างจากสัตว์เลื ้อยคลาน เช่น จิ ้งจก กิ ้งก่า
เต่า ซึง่ มีเพียงแค่สญ
ั ชาติญาณแต่ปราศจากความรู้สกึ และอารมณ์ อย่างไรก็ตามตอนที่
ทารกคลอดออกมาสมองส่วนนี ้เพิ่งสร้ างเสร็ จไปเพียง 50 % เท่านัน้ มันจะเจริ ญเติบโต
ต่อไปโดยเฉพาะในช่วงสี่ขวบปี แรกของชีวิต
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สมองส่ วนที่สองจะได้ รับอิทธิพลจากพันธุกรรมประมาณ 50 % ส่วนอีก 50 % ที่
เหลือนันพั
้ ฒนาตามสภาพแวดล้ อม ประสบการณ์และการเรี ยนรู้โดยเฉพาะช่วงตังแต่
้
แรกเกิด ขวบปี แรกจนถึงปฐมวัย (0 – 8 ปี ) สมองส่วนนี ้สําคัญมากตรงที่ เป็ น
ตัวกําหนด พืน้ อารมณ์ (Temperament) ควบคุมการแสดงออกของอารมณ์ให้
เหมาะกับเหตุการณ์ และสถานการณ์ ซึง่ เป็ นรากฐานของบุคลิกภาพของปั จเจกคน
(Individual Personality)ที่ทําให้ เราทุกคนแตกต่างกัน การที่เด็กจะเติบโตเป็ นคน
ที่ฉลาดทางอารมณ์ (Emotional Intelligence)
ทฉลาดทางอารมณ
(Emotional Intelligence) มมนุ
มีมนษยสั
ษยสมพนธดหรอไมขนอยู
มพันธ์ดีหรื อไม่ขึ ้นอย่
กับการเลี ้ยงดูในช่วงปฐมวัย และการพัฒนาของสมองส่วนนี ้เป็ นสําคัญ
สมองส่ วนที่สาม คือ สมองของสัตว์ เลีย้ งลูกด้ วยนมยุคใหม่ และเปลือกหุ้ม
สมองใหม่ (Neo‐Mammalianหรือ Neo‐Cortex Brain) คือ สมองที่พบได้
เฉพาะในสัตว์ชนสู
ั ้ งที่มีเปลือกหุ้มสมองใหญ่เท่านัน้ เช่น มนุษย์ ปลาโลมาและสัตว์
ประเภทวานร ลิง (Primates)เป็ นต้ น สมองส่วนที่สามนี ้จะมีลกั ษณะคล้ ายเปลือกหุ้ม
สมอง หุ้มสมองส่วนที่หนึง่ และส่วนที่สองเอาไว้ ตอนที่ทารกคลอดออกมาใหม่ ๆ สมอง
ส่วนนี ้ยังไม่พฒ
ั นามากเลย มันจะเริ่ มก่อร่ างสร้ างตัวและเจริ ญเติบโตอย่างรวดเร็ วมาก
ในช่วงสามปี แรกของชีวิต จนกระทัง่ เมื่อเด็กอายุได้ หกขวบจึงเจริ ญเติบโตราว 80 %
้
ิ โ
ตอนเกาขวบจะเตบโตราว
90 % และจะเจรญเตบโตเรอยตอไปกระทงอายุ
ิ ิ โ ื่ ่ ไป
ั่
25 ปปี สมอง
ส
ส่วนที่สามจะได้ รับอิทธิพลจากพันธุกรรมน้ อยมาก แทบจะเรี ยกได้ วา่ พันธุกรรมควบคุม
มัน 10-20 % เท่านัน้ เพราะมันมาเจริ ญเติบโตหลังคลอด พัฒนาการของสมองส่ วนนี ้
จึงได้ รับอิทธิพลมาจากสิ่งแวดล้ อมเป็ นส่ วนใหญ่ และต้ องการการกระตุ้นจาก
สิ่งแวดล้ อมให้ สามารถพัฒนาได้ เต็มที่ตามศักยภาพที่มีมากับตัวของเด็ก
ในสมองส่ วนที่สําคัญที่สุด ในด้ านการพัฒนาสมอง คือ สมอง
ส่ วนหน้ า (Frontal lobe) ที่อยูด่ ้ านหลังหน้ าผากของมนุษย์ หรือ สมองส่ วนปรี
ฟรอนตัล (Prefrontal Cortex) เป็ นสมองส่วนที่อยูใ่ นสมองส่วนที่สาม สาเหตุที่ทํา
ให้ สมองส่วนนี ้มีความสําคัญมาก เพราะมันมีหน้ าที่ความสําคัญเปรี ยบได้ กบั เป็ น “นาย
ของสมอง” (Chief Executive Officer หรือCEO ของสมองทัง้ หมด) เพราะเป็ น
สมองส่วนที่เกิดทีหลังสุด ในช่วงสองขวบปี แรกเพิ่งเริ่ มสร้ างเท่านันเอง
้ ทําหน้ าที่เชื่อมโยง
กับั สมองทีี่ที่สร้้ างก่อ่ นมาทังั ้ หมด สมองส่ว่ นนีีจ้ ะได้
ไ ้ รับเส้้ นประสาทมาจากสมองส่
ป
ว่ นต่า่ งๆ
เมื่อเจริ ญเติบโตเต็มที่ในช่วงที่ยา่ งเข้ าสูว่ ยั รุ่น จะเป็ นส่วนที่ควบคุมร่ างกายและจิตใจ
ทังหมด
้
ทําให้ เราเหมือนมีจิตใจเป็ นหนึง่ เดียว มีเจ้ านายคนเดียวสัง่ งาน สังเกตดูจะเห็นว่า
ช่วงวัยเด็กเล็ก เด็ก ๆ จะวิ่งเล่นตามประสา สะเปะสะปะไปตามสิ่งเร้ า สิ่งกระตุ้น เหมือน
ไม่มีการควบคุมการสัง่ งาน แต่พอเราโตขึ ้นชีวิตเริ่ มมีการวางแผน สมองส่วนนี ้นี่เองที่จะ
คอยควบคุมกําหนดให้ มนุษย์มีการวางแผนงานล่วงหน้ า มีความรับผิดชอบ มีสมาธิ
สมองส่ วนที่สาม มีความยืดหยุน่ ค่อนข้ างมาก มีบทบาทเปรียบได้ กบั หน้ าต่ าง
ของโอกาส (Windows of opportunities)ที่จะส่งเสริ มให้ เด็กฉลาดโดยการ
กระตุ้นการรับรู้ และกิจกรรมต่างๆจากประสบการณ์การเรี ยนรู้ตา่ งๆ การได้ รับอาหารที่
มีครบทุกหมู่อาหารในปริ มาณที่เหมาะสม และคุณภาพที่ดีจําเป็ นมากต่อการ
เจริ ญเติบโตของสมองส่วนนี ้ การสัมผัสและการกระตุ้นประสาทสัมผัสต่างๆอย่าง
เหมาะสมเป็ นความจําเป็ นอย่างยิ่งที่จะทําให้ สมองส่วนนี ้พัฒนาก้ าวหน้ า และสามารถ
เรี ยนร้ ประสบการณ์
เรยนรู
ระสบการณตางๆ
ตา่ งๆ ททาใหอยางเตมท
ที่ทําให้ อย่างเต็มที่ เพราะฉะนน
เพราะฉะนัน้ เรองการเลยงดู
เรื่ องการเลี ้ยงดเด็
เดกในชวง
กในช่วง
สามขวบปี แรกจึงเป็ นเรื่ องสําคัญมาก เพราะในช่วงนี ้สมองส่วนนี ้จะเจริ ญเติบโตจากที่
ไม่มีอะไรมากเลย คือ ประมาณ 25% ของผู้ใหญ่ตอนแรกเกิด จนกระทัง่ เติบโตได้ ถงึ 80
% ตอนอายุ 3 ขวบปี แรก สมองส่วนนี ้ทําให้ เด็กสามารถเรี ยนรู้ สร้ างโลกทัศน์ของการ
รับรู้ และความเข้ าใจเกี่ยวกับจักรวาลรอบตัว มีทกั ษะต่างๆในการเคลื่อนไหว เรี ยนรู้
ภาษาที่ใช้ ในการสื่อสาร ทังภาษาพู
้
ด ภาษาเขียน การคํานวณ การคิดหาเหตุผล
้
ยนรู้วิชาการต่างๆ และ
คณิตศาสตร์ และตรรกวิทยา (Logic thinking) รวมทังการเรี
จินตนาการทางศิลปะ
ปรีฟรอนตัล
Prefrontal
ภาพสมองคนแสดง สมองสามระบบ (Triune brain) สมองระบบแรก Reptilian brain ควบคุมสมดุลของการมีชีวิต
และการอยู่รอด (Homeostasis and survival) อยู่ในบริ เวณก้ านของสมอง และสมองส่วนลึกที่อยู่ใจกลางภายใน
ของสมอง ระบบที่สอง ส่วนของสมองลิมบิค (Limbic brain structures) หุ้มห่อสมองระบบแรกที่อยู่ภายใน ซึง่ ทํา
หน้ าที่เกี่ยวกับพัฒนาการของอารมณ์ ความสัมพันธ์และสังคมกับคนอื่นๆ และกับจิตใจกับความประพฤติของตัวเราเอง ระบบ
ที่สาม นีโอคอร์ เท็กซ์ (Neocortex) เป็ นส่วนเปลือกที่ห้ มุ ห่อภายนอกของสมองใหญ่ ทัง้ Cerebrum and cerebellum ควบคุมการรับรู้ การเรียนรู้ และทักษะความชํานาญ และความเฉลียวฉลาด รวมทังบริ
้ เวณ ปรีฟรอนตัล
(Prefrontal) ที่เป็ น นายหรือ CEO ของสมอง
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ทีมงานวิจยั ของมหาวิทยาลัยไอโอวานําโดยประสาทแพทย์ชื่อ ดร.อันโตนิ
โอ ดามาสซิโอ (Dr. Antonio Damassio) และภรรยา ดร.ฮันนา ดามาสซิโอ (Dr.
Hanna Damassio) ได้ ทําการวิจยั ติดตามเด็กเล็กที่เมื่ออายุประมาณขวบหรื อขวบ
ครึ่งเคยได้ รับบาดเจ็บจากอุบตั ิเหตุ เช่น หกล้ มไปข้ างหน้ า แล้ วศีรษะส่วนหน้ าผาก
ฟาดพื น้ ทํา ให้ สมองบริ เ วณนัน้ เกิ ด อาการชํ า้ ทีมงานวิจัย ติดตามเด็ก กลุ่มนี ไ้ ป
จนกระทัง่ วัยรุ่ นแล้ วพบว่า เด็กกลุ่มนี ้จะมีอาการทางประสาท ที่จิตแพทย์เรี ยกว่า
สมองส่ วนหน้ าพิการ (Frontal lobe syndrome) คือ เด็กที่สมองส่วนหน้ าทํางาน
ไม่สมบูรณ์ ทําให้ ประสบปั ญหาเรื่ องการเรี ยน และพฤติกรรมแม้ ว่าบางคนจะมีไอ
คิวิ (IQ) สูงก็็ตาม เนืื่องจากมีีสมาธิิสนั ้ (Attention Deficit หรืื อ AD)) ไม่
ไ สามารถ
ควบคุมตัวเองให้ สงบนิ่ง ที่จะทําอะไรนิ่งๆ อยู่กบั ที่นาน ๆ ได้ พอ ไม่มีการวางแผนที่
ดี ขาดความรับผิดชอบ และมีปัญหาในการเรี ยน และการเข้ าสมาคมกับคนอื่นๆ
เด็กวัยรุ่ นที่มาจากครอบครัวที่ดีแต่ตวั เด็กกลับมีพฤติกรรมไม่เหมาะสม และเป็ น
อันธพาลชอบต่อต้ านกฎระเบียบต่างๆ ต่อต้ านสังคม และบางครั ง้ ชอบใช้ ความ
ก้ าวร้ าวและพฤติกรรมรุ นแรง นัน้ เมื่อศึกษาลึกลงไป จะพบว่ามีสาเหตุเกี่ยวกับ
ความพิการของสมองส่วนนีเ้ ข้ า มาเกี่ ย วข้ องได้ เสมอ ดัง นัน้ จึงควรดูแลป้องกัน
ระมัดระวังไม่ให้ ศีรษะส่วนนี ้ของเด็กทารกได้ รับบาดเจ็บ
Corpus callosum
Prefrontal lobe syndrome
•
•
•
•
•
Personality changes
Deficits in strategic planning
Perseveration
Release of primitive reflexes
Abulia = general slowing of the intellectual faculties i.e. apathetic, slow speech etc.
415703 Cognitive Neuropsychology
Week 2:
How neurons communicate, effects of How neurons communicate, effects of drugs on the brain, and functional drugs on the brain, and functional brain brain imaging
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
Main Objectives:
1. How neurons communicate?
2. Concepts of chemical neurotransmissions and various neurotransmitters and neuromodulators?
3. Effects of various chemicals and drugs on the brain (Nervous System).
4. Concepts of functional localization in the brain and brain mapping.
5. Brain Imaging and Functional Brain Imaging.
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Axon terminal
Synaptic cleft
Excitation:
EPSP
Inhibition:
IPSP
สารสื่อประสาท (Neurotransmitters ) ที่สาํ คัญในสมอง
Biogenic amines
Amino acids
Neuropeptides
‐Acetyl Choline
‐Glutamic acid
‐Enkephalins
‐Norepinephrine
‐Aspartic acid
‐Endorphins
‐Dopamine
‐Glycine
‐Dynorphins
‐Serotonin
‐GABA
‐Substance P
‐Histamine
Polyamines
‐VIP
‐Epinephrine
‐Taurine
‐Somatostatin
‐CCK
Diagram of cholinergic nerve terminal with prototype drugs and chemicals
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Neurotransmitters in Somatic and Autonomic nervous system
Cholinergic pathways in human brain
Ach: Acetyl choline
NE: Norepinephrine
NE: Norepinephrine
E: Epinephrine
GABA: Gamma amino butyric acid
Glutamate
Dopamine
VTA: Ventral tegment
al area
Dopamine pathway in the human brain
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Central Noradrenergic nerve terminal
Locus coeruleus
Locus coeruleus
Cocaine and other local anesthetics
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ลักษณะของยาและสารเสพติด
Brain Reward System
‐Psychotomimetics, and some are Psychedelics
‐Euphoria, Ecstasy etc.
‐Reward and Reinforcement
‐Tolerance
‐Withdrawal syndromes and Dysphoria
y
yp
‐Physical, psychological and behavioural dependence
‐Craving
‐Compulsive drug seeking behaviour
‐Relapse
Serotonin
5‐hydroxy tryptamine
Raphe nucleus
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415703 Cognitive Neuropsychology
Week 3:
Sensory ‐motor and cortical Sensory ‐
organization
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
Main Objectives:
1. Sensory ‐ motor and cortical organization?
2. The sensory systems?
3. The Reticular formation, Sensory‐Motor Integration for states of Consciousness, Waking, Sleep and Dream.
4. The Motor System, Movements and Motor Controls
5. The Cerebral Cortex, and Cortical Columnar Organization, Concepts of functional localization and representation in the brain and brain mapping.
6. Brain Imaging and Functional Brain Imaging.
sensory system is a part of the nervous system
responsible for processing sensory information. A sensory system consists of sensory receptors, neural pathways, and parts of the brain involved in sensory perception. Commonly recognized sensory systems are those for vision, hearing, somatic sensation (touch), taste and olfaction (smell). In short, senses are transducers from the physical world to the realm of the mind.
The receptive field is the specific part of the world to which a receptor organ and receptor cells respond. For instance, the part of the world an eye can see, is its receptive field; the light that each rod or cone can see, is its receptive field. Receptive fields
have been identified for the visual system, auditory system and somatosensory system, so far.
Somatosensory system
Dermatome
Reticular Formation
Ascending Reticular Activating System (ARAS)
Regulation of States of Consciousness, e.g. waking, Sleep, Dream; attention; sensory‐‐motor sensory
integration
Reticular formation
is a part of the brain that is involved in actions such as
awaking/sleeping cycle, and filtering incoming stimuli to discriminate irrelevant background stimuli. It is
essential for governing some of the basic functions of higher organisms, and is one of the
phylogenetically oldest portions of the brain. The reticular formation consists of more than 100 small
neural networks, with varied functions including the following:
1. Somatic motor control ‐ Some motor neurons send their axons to the reticular formation nuclei,
giving rise to the reticulospinal tracts of the spinal cord. These tracts function in maintaining tone,
balance, and posture‐‐especially during body movements. The reticular formation also relays eye and
ear signals to the cerebellum so that the cerebellum can integrate visual, auditory, and vestibular stimuli
in motor coordination. Other motor nuclei include gaze centers, which enable the eyes to track and
fixate objects, and central pattern generators, which produce rhythmic signals to the muscles of
breathing and swallowing.
2. Cardiovascular
2.
C di
l controll ‐ The
Th reticular
i l formation
f
i includes
i l d the
h cardiac
di and
d vasomotor centers off the
h
medulla oblongata.
3. Pain modulation ‐ The reticular formation is one means by which pain signals from the lower body
reach the cerebral cortex. It is also the origin of the descending analgesic pathways. The nerve fibers in
these pathways act in the spinal cord to block the transmission of some pain signals to the brain.
4. Sleep and consciousness ‐ The reticular formation has projections to the thalamus and cerebral
cortex that allow it to exert some control over which sensory signals reach the cerebrum and come to
our conscious attention. It plays a central role in states of consciousness like alertness and sleep. Injury
to the reticular formation can result in irreversible coma.
5. Habituation ‐ This is a process in which the brain learns to ignore repetitive, meaningless stimuli while
remaining sensitive to others. A good example of this is when a person can sleep through loud traffic in
a large city, but is awakened promptly due to the sound of an alarm or crying baby. Reticular formation
nuclei that modulate activity of the cerebral cortex are called the reticular activating system or
extrathalamic control modulatory system.
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The Human Reticular Formation:
Reticular Functions:
‐ Integration of Sensory and motor functions
‐ Control of states of consciousness
Waking, Sleep, Dream, Altered States
‐ Control of behavioural states
‐ Arousal, Attention, Orienting, Habituation
Arousal Attention Orienting Habituation
‐ Sensory filtering (“The Cocktail Party Effect”)
‐ Motor functions:
Postural Controls
Eye movements: Gaze, Saccade, REM
‐ Autonomic controls:
respiration, heart rates, blood pressure
ARAS:
Ascending
Reticular
Activating
System
415703 Cognitive Neuropsychology
Week 4:
The occipital lobes
The occipital lobes
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
Main Objectives:
1. The occipital The occipital lobes and their functions
lobes and their functions
2. The Visual System
3. Visual Perception and Visual Cortical Organization
4 The
4.
The two Stream Hypothesis: The Dorsal stream, two Stream Hypothesis: The Dorsal stream
“Where or How” and The Ventral Stream, “What”
5. Neuropsychology of the Occipital lobes.
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Occipital lobe
Vision processing
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1 (visual one). Human V1 is located on the medial side of the occipital lobe within the calcarine sulcus; the full extent of V1 often continues onto the posterior pole of the occipital lobe. V1 is often also called striate cortex because it can be identified by a large stripe of myelin, the Stria
ti
f
li th St i of Gennari. Visually driven regions fG
i Vi ll d i
i
outside V1 are called extrastriate cortex. There are many extrastriate regions, and these are specialized for different visual tasks, such as visuospatial processing, color discrimination and motion perception. The name derives from the overlying occipital bone, which is named from the Latin oc‐ + caput, "back of the head".
Functions of the Occipital lobes:
Significant functional aspects of the occipital lobe is that it contains the primary visual cortex and is the part of the brain where dreams come from.
Retinal sensors convey stimuli through the optic tracts to the lateral geniculate
bodies, where optic radiations continue to the visual cortex. Each visual cortex receives raw sensory information from the outside half of the retina on the same side of the head and from the inside half of the retina on the other side of the head. The cuneus (Brodmann's area 17) receives visual information from the contralateral superior retina representing the inferior visual field. The lingula
receives information from the contralateral inferior retina representing the
receives information from the contralateral inferior retina representing the superior visual field. The retinal inputs pass through a "way station" in the lateral geniculate nucleus of the thalamus before projecting to the cortex. Cells on the posterior aspect of the occipital lobes' gray matter are arranged as a spatial map of the retinal field. Functional neuroimaging reveals similar patterns of response in cortical tissue of the lobes when the retinal fields are exposed to a strong pattern.
If one occipital lobe is damaged, the result can be homonomous vision loss from similarly positioned "field cuts" in each eye. Occipital lesions can cause visual hallucinations. Lesions in the parietal‐temporal‐occipital association area are associated with color agnosia, movement agnosia, and agraphia.
The occipital lobe is divided into several functional visual areas. Each visual area contains a full map of the visual areas. world. Although there are no anatomical markers distinguishing these areas (except for the prominent striations in the striate cortex), physiologists have used electrode recordings to divide the cortex into different functional regions.
The first functional area is the primary visual cortex It
The first functional area is the primary visual cortex. It contains a low‐level description of the local orientation, spatial‐frequency and color properties within small receptive fields. Primary visual cortex projects to the occipital areas of the ventral stream (visual area V2 and visual area V4), and the occipital areas of the dorsal stream—visual area V3, visual area MT (V5), and the dorsomedial area (DM).
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The visual system is the part of the central nervous system which enables organisms to process visual detail, as well as enabling several non‐image forming photoresponse functions. It interprets information from visible light to build a representation of the surrounding world. The visual system accomplishes a number of complex tasks, including the reception of light and the formation of monocular representations; the construction of a binocular perception from a pair of two dimensional projections;
binocular perception from a pair of two dimensional projections; the identification and categorization of visual objects; assessing distances to and between objects; and guiding body movements in relation to visual objects. The psychological manifestation of visual information is known as visual perception, a lack of which is called blindness. Non‐image forming visual functions, independent of visual perception, include the pupillary light reflex (PLR) and circadian photoentrainment.
The visual system includes the eyes, the connecting pathways through to the visual cortex and other parts of the brain. The illustration shows the mammalian system.
Controls of eye
movements
Oculomotor (CN3)
Trochlear (CN4)
Abducens (CN6)
PPRF
PRF
Frontal eye field
(Area #8)
NEUROPSYCHIATRY
177
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Primary visual cortex (V1
Primary visual cortex (V
1) The primary visual cortex is the best studied visual area in the brain. In all The primary visual cortex mammals studied, it is located in the posterior pole of the occipital cortex (the occipital cortex is responsible for processing visual stimuli). It is the simplest, earliest cortical visual area. It is highly specialized for processing information about static and moving objects and is excellent in pattern recognition.
The functionally defined primary visual cortex is approximately equivalent to the anatomically defined striate cortex. The name "striate cortex" is derived from the stria of Gennari, a distinctive stripe visible to the naked eye that represents m elinated axons
myelinated
a ons from the lateral geniculate
from the lateral genic late body
bod terminating in layer 4 of the terminating in la er 4 of the
gray matter.
The primary visual cortex is divided into six functionally distinct layers, labeled 1 through 6. Layer 4, which receives most visual input from the lateral geniculate
nucleus (LGN), is further divided into 4 layers, labelled 4A, 4B, 4Cα, and 4Cβ. Sublamina 4Cα receives most magnocellular input from the LGN, while layer 4Cβ receives input from parvocellular pathways.
The average number of neurons in the adult human primary visual cortex, in each hemisphere, has been estimated at around 140 million (Leuba & Kraftsik, Anatomy and Embryology, 1994).
V1 1 has a very well
has a very well‐‐defined map of the spatial information in vision
. . For example, in humans For example, in humans the upper bank of the the upper bank of the calcarine
calcarine sulcus responds strongly to the lower half of responds strongly to the lower half of visual field
visual field (below the center), and the lower bank of the mapping is a transformation of the visual image from retina
retina to calcarine to the upper half of visual field. Conceptually, this to the upper half of visual field. Conceptually, this retinotopic
retinotopic mapping is a transformation of the visual image from V1. The correspondence between a given location in V1 . The correspondence between a given location in V1 and in the subjective visual field is very precise: even the and in the subjective visual field is very precise: even the blind spots
blind spots are mapped into V
mapped into V1
1. Evolutionarily, this correspondence is very basic and found in most animals that possess a V1
. Evolutionarily, this correspondence is very basic and found in most animals that possess a V1. In human and animals fovea in the retina, a large portion of V1 in the retina, a large portion of V1 is mapped to the small, central portion of visual field, a phenomenon known as is mapped to the small, central portion of visual field, a phenomenon known as cortical cortical with a with a fovea
magnification. Perhaps for the purpose of accurate spatial encoding, neurons in V
magnification
. Perhaps for the purpose of accurate spatial encoding, neurons in V1 1 have the smallest receptive field size of any visual have the smallest receptive field size of any visual cortex microscopic regions.
The tuning properties of V1 neurons (what the neurons respond to) differ greatly over time. Early in The tuning properties of V1 neurons (what the neurons respond to) differ greatly over time. Early in time (40 time (
40 ms and further) individual V
ms and further) individual V1 1 neurons have strong tuning to a small set of stimuli.
neurons have strong tuning to a small set of stimuli. That is, the neuronal responses can discriminate small changes in visual orientations, spatial neuronal responses can discriminate small changes in visual orientations, spatial frequencies
frequencies and and colors
colors. Furthermore, individual V
. Furthermore, individual V1 1 have ocular dominance, namely tuning to one of the two eyes. In V1
1, and primary neurons in human and animals with neurons in human and animals with binocular vision
binocular vision have ocular dominance, namely tuning to one of the two eyes. In V
David Hubel and and Torsten
Torsten
sensory cortex in general, neurons with similar tuning properties tend to cluster together as cortical columns. sensory cortex in general, neurons with similar tuning properties tend to cluster together as cortical columns. David Hubel
Wiesel proposed the classic ice
proposed the classic ice‐‐cube organization model of cortical columns for two tuning properties: ocular dominance and orientation. However, this model cannot accommodate the color, spatial frequency and many other features to which neurons are
tuned. The exact organization of all these cortical columns within V
tuned. The exact organization of all these cortical columns within V1 1 remains a hot topic of current research.
remains a hot topic of current research.
Current consensus seems to be that early responses of V1 Current consensus seems to be that early responses of V1 neurons consists of tiled sets of selective spatiotemporal filters. In the spatial neurons consists of tiled sets of selective spatiotemporal filters. In the spatial 1 can be thought of as similar to many spatially local, complex can be thought of as similar to many spatially local, complex Fourier transforms
Fourier transforms, or more accurately, , or more accurately, domain, the functioning of V
domain, the functioning of V1 . Theoretically, these filters together can carry out neuronal processing of spatial frequency, orientation, motion, Gabor transforms. Theoretically, these filters together can carry out neuronal processing of spatial frequency, orientation, motion, Gabor transforms
direction, speed (thus temporal frequency), and many other spatiotemporal features. Experiments of neurons substantiate these
theories, but also raise new questions.
organisation of the scene (Lamme
of the scene (Lamme & & Roelfsema
Roelfsema, , 2000
2000). ). Later in time (after 100 Later in time (after 100 ms) neurons in V
ms) neurons in V1 1 are also sensitive to the more global are also sensitive to the more global organisation
tical These response properties probably stem from recurrent processing (the influence of higher‐
These response properties probably stem from recurrent processing (the influence of higher‐tier cortical areas on lower
tier cortical areas on lower‐‐tier cor
tier cortical areas) and lateral connections from pyramidal neurons (Hupe
areas) and lateral connections from pyramidal neurons (
Hupe et al. 1998
et al. 1998). While ). While feedforward
feedforward connections are mainly driving, feedback ; Hupe
Hupe et al., 2001
et al., 2001). Evidence shows that feedback originating ). Evidence shows that feedback originating connections are mostly modulatory
connections are mostly modulatory in their effects (Angelucci
in their effects (Angelucci et al., 2003
et al., 2003; responses, in higher level areas such as V
in higher level areas such as V4
4, IT or MT, with bigger and more complex receptive fields, can modify and shape V1 , IT or MT, with bigger and more complex receptive fields, can modify and shape V1 responses, ; Huang et al., 2007
2007; ; Sillito
Sillito et al., accounting for contextual or extra
accounting for contextual or extra‐‐classical receptive field effects (Guo
classical receptive field effects (Guo et al., 2007
et al., 2007; Harrison et al., ; Harrison et al., 2007
2007; Huang et al., 2006).
2006
).
The visual information relayed to V1 The visual information relayed to V
1 is not coded in terms of spatial (or optical) imagery, but rather as is not coded in terms of spatial (or optical) imagery, but rather as the local contrast. As an example, for an image comprising half side black and half side white, the divide line between black and white has strongest local contrast and is encoded, while few neurons code the brightness information (black or white per se). As
local frequency/phase signals. Importantly, at antly, at information is further relayed to subsequent visual areas, it is coded as increasingly non
information is further relayed to subsequent visual areas, it is coded as increasingly non‐‐local frequency/phase signals. Import
these early stages of cortical visual processing, spatial location of visual information is well preserved amid the local con
these early stages of cortical visual processing, spatial location of visual information is well preserved amid the local contra
trast encoding.
st encoding.
Third visual complex, including area V3
The term third visual complex refers to the region of cortex located immediately in front of V
located immediately in front of V2
2, which includes the region named visual area V3 includes the region named visual area V3 in humans
in humans. The "complex" nomenclature is justified by the fact that some controversy still exists regarding the exact extent of area V3, with some researchers proposing that the cortex located in front of V2 may include two or three functional subdivisions. For example, David Van Essen and others (1986) have proposed that the existence of a "dorsal V3" in the upper part of the cerebral hemisphere, which is distinct from the "ventral V3" (or ventral posterior area, VP) located in the lower part of the brain. Dorsal and ventral V3 have distinct connections with other parts of the brain, appear different in sections stained with a variety of methods, and contain neurons that respond to different combinations of visual stimulus (for example, colour‐selective neurons are more common in the ventral V3). Additional subdivisions, including V3A and V3B have also been reported in humans. These subdivisions are located near dorsal V3, but do not adjoin V2.
Dorsal V
Dorsal V3 3 is normally considered to be part of the dorsal stream, receiving inputs from V
is normally considered to be part of the dorsal stream, receiving inputs from V2 y
p
,
g p
2 and from and from the primary visual area and projecting to the posterior parietal cortex
the primary visual area and projecting to the posterior parietal cortex. . It may be anatomically located in Brodmann area 19. Recent work with fMRI has suggested that area V3/V3A may play a role in the processing of global motion Other studies prefer to consider dorsal V3 as part of a larger area, named the dorsomedial area (DM), which contains a representation of the entire visual field. Neurons in area DM respond to coherent motion of large patterns covering extensive portions of the visual field (Lui
and collaborators, 2006).
Ventral V3 (VP), has much weaker connections from the primary visual area, and stronger connections with the inferior temporal cortex. While earlier studies proposed that VP only contained a representation of the upper part of the visual field (above the point of fixation), more recent work indicates that this area is more extensive than previously appreciated, and like other visual areas it may contain a complete visual representation. The revised, more extensive VP is referred to as the ventrolateral posterior area (VLP) by Rosa and Tweedale.
Visual area V2
Visual area V
2
, also called prestriate
, also called prestriate cortex, is the second major area in the visual cortex, and the first region within the visual association area. It receives strong feedforward connections from V1 (direct and via the pulvinar) and sends strong connections to V3, V4, and V5. It also sends strong feedback connections to V1.
Anatomically, V2 Anatomically, V
2 is split into four quadrants, a is split into four quadrants, a dorsal
dorsal and and ventral
ventral representation in the left and the right hemispheres
right hemispheres. Together these four regions provide a complete map of the visual world. Functionally, V2 has many properties in common with V1. Cells are tuned to simple properties such as orientation, spatial frequency, and color. The responses of many V
The responses of many V2 2 neurons are also modulated by neurons are also modulated by more complex properties, such as the orientation of illusory contours and whether the stimulus is part of the figure or the ground (Qiu and von der Heydt, 2005).
Recent research has shown that V2 cells show a small amount of attentional modulation (more than V1, less than V4), are tuned for moderately complex patterns, and may be driven by multiple orientations at different subregions within a single receptive field.
It is argued that the entire ventral visual‐to‐hippocampal stream is important for visual memory. This theory, unlike the dominant one, predicts that object‐recognition memory (ORM) alterations could result from the manipulation in V2, an area that is highly interconnected within the ventral stream of visual cortices. In the monkey brain, this area receives strong feedforward connections from the primary visual cortex (V1) and sends strong projections to other secondary visual cortices (V3, V4, and V5) . Most of the neurons of this area are tuned to simple visual characteristics such as orientation, spatial frequency, size, color, and shape and V
frequency, size, color, and shape and V2 2 cells also respond to various complex shape characteristics, cells also respond to various complex shape characteristics, such as the orientation of illusory contours and whether the stimulus is part of the figure or the ground . Anatomical studies implicate layer 3 of area V2 in visual‐information processing. In contrast to layer 3, layer 6 of the visual cortex is composed of many types of neurons, and their response to visual stimuli is more complex.
In a recent study, the Layer 6 cells of the V2 cortex were found to play a very important role in the storage of Object Recognition Memory as well as the conversion of short‐term object memories into long‐term memories.
Visual area V4 Visual area V4 is one of the visual areas in the extrastriate visual cortex. It is located anterior to V2 and posterior to posterior inferotemporal area (PIT). It comprises at least four regions (left and right V4d, left and right V4v), and some groups report that it contains rostral and caudal subdivisions as well. It is unknown what the human homologue of V4 is, and this issue is currently the subject of much scrutiny.
V4 is the third cortical area in the ventral stream, receiving strong feedforward input from V2 and sending strong connections to the PIT. It also receives direct inputs from V1, especially for central space. In addition, it has weaker connections to V5 and dorsal prelunate gyrus (DP).
V4 is the first area in the ventral stream to show strong attentional modulation. Most studies indicate that selective attention can change firing rates in V4 by about 20%. A seminal paper by Moran and Desimone characterizing these effects was the first paper to find attention effects anywhere in the visual cortex.
Like V1, V4 is tuned for orientation, spatial frequency, and color. Unlike V1, V4 is tuned for object ,
, p
q
y,
,
j
features of intermediate complexity, like simple geometric shapes, although no one has developed a full parametric description of the tuning space for V4. Visual area V4 is not tuned for complex objects such as faces, as areas in the inferotemporal cortex are.
The firing properties of V4 were first described by Semir Zeki in the late 1970s, who also named the area. Before that, V4 was known by its anatomical description, the prelunate gyrus. Originally, Zeki
argued that the purpose of V
purpose of V4 4 was to process color information
was to process color information. Work in the early 1980s proved that V4 was as directly involved in form recognition as earlier cortical areas. This research supported the Two Streams hypothesis, first presented by Ungerleider and Mishkin in 1982.
Recent work has shown that V4 exhibits long‐term plasticity, encodes stimulus salience, is gated by signals coming from the frontal eye fields and shows changes in the spatial profile of its receptive fields with attention.
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V5/MT Visual area V
/MT Visual area V5
5
, also known as visual area MT (middle temporal), is a region of extrastriate visual cortex that is thought to play a major role in the perception of motion, the integration of local motion signals into global percepts and the guidance of some eye movements
MT is connected to a wide array of cortical and subcortical brain areas. Its inputs include the visual cortical areas V1, V2, and dorsal V3 (dorsomedial area), the koniocellular regions of the LGN, and the inferior pulvinar. The pattern of projections to MT changes somewhat between the representations of the foveal
and peripheral visual fields, with the latter receiving inputs from areas located in the midline cortex and retrosplenial
e d e co e a d e osp e a region eg o
A standard view is that V1 provides the "most important" input to MT.
Nonetheless, several studies have demonstrated that neurons in MT are capable of responding to visual information, often in a direction‐selective manner, even after V1 has been destroyed or inactivated. Moreover, research by Semir Zeki
and collaborators has suggested that certain types of visual information may reach MT before it even reaches V1.
MT sends its major outputs to areas located in the cortex immediately surrounding it, including areas FST, MST and V4t (middle temporal crescent). Other projections of MT target the eye movement‐related areas of the frontal and parietal lobes (frontal eye field and lateral intraparietal area).
Function of V5/MT
The first studies of the electrophysiological properties of neurons in MT showed that a large portion of the cells were tuned to the speed and direction of moving visual stimuli These results suggested that MT played a significant role in the processing of visual motion.
Lesion studies have also supported the role of MT in motion perception and eye tudies have also supported the role of MT in motion perception and eye movements and neuropsychological
movements and neuropsychological studies of a patient who could not see motion, seeing the world in a series of static "frames" instead, suggested that MT in the primate is homologous to V5 homologous to V
5 in the human.
in the human.
However, since neurons in V1 are also tuned to the direction and speed of motion, these early results left open the question of precisely what MT could do that V1 could not. Much work has been carried out on this region as it appears to integrate local visual motion signals into the global motion of complex objects] For example, lesion to the V5 lead to deficits in perceiving motion and processing of complex stimuli. It contains many neurons selective for the motion of complex visual features (line ends, corners). Microstimulation of a neuron located in the V5 affects the perception of motion. For example, if one finds a neuron with preference for upward motion, and then we use an electrode to stimulate it, the monkey becomes more likely to report 'upward' motion.
There is still much controversy over the exact form of the computations carried out in area MT and some research suggests that feature motion is in fact already available at lower levels of the visual system such as V1
MT was shown to be organized in direction columns.
NEUROPSYCHIATRY
Organization of V1 and V2.
A. Subregions in V1 (area 17) and V2 (area 18). This section from the occipital lobe of a squirrel
monkey at the border of areas 17 and 18 was reacted with cytochrome oxidase. The cytochrome
oxidase stains the blobs in V1 and the thick and thin stripes in V2. (Courtesy of M. Livingstone.)
B Connections between V1
B. Connections between V1 and V2. The blobs in V1 connect primarily to the thin stripes in V2, while
the interblobs in V1 connect to interstripes in V2. Layer 4B projects to the thick stripes in V2 and to
the middle temporal area (MT). Both thin and interstripes project to V4. Thick stripes in V2 also
project to MT.
190
Callosal Disconnection Syndromes
NEUROPSYCHIATRY
192
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415703 Cognitive Neuropsychology
Week 5:
The Parietal lobes
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
NEUROPSYCHIATRY
193
Main Objectives:
1. The The Parietal lobes and their functions
Parietal lobes and their functions
2. The Somatosensory System
3. Somatosensory Perception and Somatosensory Cortical Organization
4 The
4.
The two Stream Hypothesis: The Dorsal stream, two Stream Hypothesis: The Dorsal stream
“Where or How” and The Ventral Stream, “What”
5. Neuropsychology of the Parietal lobes.
The parietal lobe is a part of the Brain positioned above (superior to) the occipital lobe and behind (posterior to) the frontal lobe.
The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the dorsal stream
somatosensory cortex
and the dorsal stream of the visual of the visual
system. This enables regions of the parietal cortex to map objects perceived visually into body coordinate positions.
The name derives from the overlying parietal bone, which is named from the Latin pariet‐, wall.
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The parietal lobe is defined by four anatomical boundaries: the central sulcus separates the parietal lobe from the frontal lobe; the parieto‐occipital sulcus separates the parietal and occipital lobes; the lateral sulcus (sylvian
fissure) is the most lateral boundary separating it from the temporal lobe; and the medial longitudinal fissure divides the two hemispheres.
Immediately posterior to the central sulcus, and the most anterior part of the parietal lobe, is the postcentral gyrus (Brodmann area 3), the secondary somatosensory cortical area. Dividing this and the posterior parietal cortex
is the postcentral sulcus.
The posterior parietal cortex can be subdivided into the superior parietal p
p
p
p
lobule (Brodmann areas 5 + 7) and the inferior parietal lobule (39 + 40), separated by the intraparietal sulcus (IPS). The intraparietal sulcus and adjacent gyri are essential in guidance of limb and eye movement, and based on cytoarchitectural and functional differences is further divided into medial (MIP), lateral (LIP), ventral (VIP), and anterior (AIP) areas
Parietal lobe Function
The parietal lobe plays important roles in integrating sensory information from various parts of the body, knowledge of numbers and their relations, and in the manipulation of objects. Portions of the parietal lobe are involved with visuospatial processing. Although multisensory in nature, the posterior parietal cortex is often referred to by vision scientists as the dorsal stream of vision (as opposed to the ventral stream in the temporal lobe). This dorsal stream has been called both the 'where' stream (as in spatial vision) and the 'how' stream (as in vision for action).
Various studies in the 1990s found that different regions of the posterior parietal cortex in Macaques represent different parts of space.
► The lateral The lateral intraparietal
intraparietal (LIP) contains a map of neurons (retinotopically‐coded when (LIP) the eyes are fixed) representing the saliency of spatial locations, and attention to these
the eyes are fixed) representing the saliency of spatial locations, and attention to these spatial locations. It can be used by the oculomotor system for targeting eye movements, when appropriate.
►The ventral The ventral intraparietal
intraparietal (VIP) area receives input from a number of senses (visual, (VIP) somatosensory, auditory, and vestibular). Neurons with tactile receptive fields represented space in a head‐centered reference frame. The cells with visual receptive fields also fire with head‐centered reference frames but possibly also with eye‐centered coordinates
► The medial The medial intraparietal
intraparietal (MIP) area neurons encode the location of a reach target in (MIP) nose‐centered coordinates. (AIP) ► The anterior intraparietal
The anterior intraparietal (AIP) area contains neurons responsive to shape, size, and orientation of objects to be grasped as well as for manipulation of hands themselves, both to viewed and remembered stimuli.
The somatosensory system
The somatosensory system is a diverse sensory system comprising the receptors and processing centres to produce the sensory modalities such as touch, temperature, proprioception (body position), and nociception (pain). The sensory receptors cover the skin and epithelia, skeletal muscles, bones and joints, internal organs, and the cardiovascular system. While touch (also, more formally, tactition; adjectival form: "tactile" or "somatosensory") is considered one of the five traditional senses, the impression of touch is formed from several modalities. In medicine, the colloquial term touch is usually replaced with somatic senses to better reflect the variety of mechanisms involved.
The system reacts to diverse stimuli using different receptors: thermoreceptors, nociceptors, mechanoreceptors and chemoreceptors. Transmission of information from the receptors passes via sensory nerves
h
i
through tracts in the spinal cord
h
h
i h
i l
d and into the di
h
brain. Processing primarily occurs in the primary somatosensory area in the parietal lobe
of the cerebral cortex.
The cortical homunculus was devised by Wilder Penfield.
At its simplest, the system works when activity in a sensory neuron is triggered by a specific stimulus such as heat; this signal eventually passes to an area in the brain uniquely attributed to that area on the body—this allows the processed stimulus to be felt at the correct location. The point‐to‐point mapping of the body surfaces in the brain is called a homunculus and is essential in the creation of a body image. This brain‐surface ("cortical") map is not immutable, however. Dramatic shifts can occur in response to stroke or injury.
Somatosensory system
Dermatome
Somatic sensory
areas of the cortex.
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Postcentral gyrus
The lateral postcentral gyrus is bounded by:
The neural architecture of
the somatosensory system.
medial longitudinal fissure medially (to the middle) central sulcus rostrally (in front) postcentral sulcus caudally (in back) lateral sulcus inferiorly (underneath) It is the location of i h l
i
f primary i
somatosensory cortex, the main sensory receptive area for the sense of touch. Like other sensory areas, there is a map of sensory space called a homunculus in this location. For the primary somatosensory cortex, this is called the sensory homunculus
sensory homunculus.
A somatotopic map of
the body surface onto
primary somatosensory
cortex.
Somatosensory
homunculus
Brodmann areas 3, 1 and 2 comprise the primary somatosensory cortex of the human brain
(or S1). Because Brodmann sliced the brain somewhat obliquely, he encountered area 1 first; however, from rostral to caudal the Brodmann designations are 3, 1 and 2, respectively.
Brodmann area 3 is subdivided into area 3a and 3b. Where BA 1 occupies the apex of the postcentral gyrus, the rostral border of BA 3a is in the nadir of the Central sulcus, and is caudally followed by BA 3b, then BA 1, with BA 2 following and ending in the nadir of the postcentral sulcus. BA 3b is now conceived as the primary somatosensory cortex because 1) it receives dense inputs from the NP nucleus of the thalamus; 2) its neurons are highly responsive to somatosensory stimuli, but not other stimuli; 3) lesions here impair somatic sensation; and 4) electrical stimulation evokes somatic sensory experience. BA 3a also receives dense input from the thalamus; however, this area is concerned with proprioception.
Areas 1 and 2 receive dense inputs from BA 3b. The projection from 3b to 1 primarily relays texture information; the projection to area 2 emphasizes size and shape. Lesions confined to these areas produce predictable dysfunction in texture, size, and shape discrimination.
Somatosensory cortex, like other neocortex, is layered. Like other sensory cortex (i.e. visual and auditory) the thalamic inputs project into layer IV, which in turn project into other layers. Also like other sensory cortices, S1 neurons are grouped together with similar inputs and responses into vertical columns that extend across cortical layers (e.g. As shown by Vernon Mountcastle, into alternating layers of slowly adapting and rapidly adapting neurons; or spatial segmentation of the vibrissae on mouse/rat cerebral cortex).
This area of cortex, as shown by Wilder Penfield and others, is organized somatotopically, having the pattern of a homunculus. That is, the legs and trunk fold over the midline; the arms and hands are along the middle of the area shown here; and the face is near the bottom of the figure. While it is not well‐shown here, the lips and hands are enlarged on a proper homunculus, since a larger number of neurons in the cerebral cortex are devoted to processing information from these areas.
The positions of Brodmann area's 3, 1 and 2 are ‐ from the nadir of the central sulcus towards the apex of the postcentral gyrus ‐ 3a, 3b, 1 and 2 respectfully.
These areas contain cells that project to the secondary somatosensory cortex.
The human secondary somatosensory cortex (S2
The human secondary somatosensory cortex (S2) is a region of cerebral cortex lying mostly on the parietal operculum.
Region S2 was first described by Adrian in 1940, who found that feeling in cats' feet was not only represented in the previously described primary somatosensory cortex (S1) but also in a second region adjacent to S1. In 1954, Penfield and Jasper evoked somatosensory sensations in human patients during neurosurgery using electrical stimulation in the lateral sulcus, which lies adjacent to S1, and their findings were confirmed in 1979 by Woolsey et al. using evoked potentials and electrical stimulation. Functional neuroimaging studies have found S2 activation in response to light touch, pain, visceral sensation, and tactile attention.
In monkeys, apes and hominids region S2 is divided into several "areas". The area adjoining the primary somatosensory cortex is called the parietal ventral area (PV). Adjacent to PV, but towards the posterior of the parietal operculum is area S2 which must not be confused with region
posterior of the parietal operculum, is area S2 ‐
which must not be confused with region S2 (which S2 (which
designates the entire secondary somatosensory cortex, of which area S2 is a part). Deeper in the lateral sulcus, bordering areas PV and S2, lies the ventral somatosensory area (VS). In humans, the secondary somatosensory cortex includes parts of Brodmann areas 40 and 43.
Areas PV and S2 both map the body surface. Functional neuroimaging in humans has revealed that in areas PV and S2 the face is represented nearest the entrance to the lateral sulcus, and the hands and feet deeper in the fissure, nearer the border with VS. Individual neurons in PV and S2 receive input from wide areas of the body surface (they have large "receptive fields"), and respond readily to stimuli such as wiping a sponge over a large area of skin.
Areas S2 in the left and right hemispheres are densely interconnected, and stimulation on one side of the body will activate area S2 in both hemispheres. Area S2 is interconnected with Brodmann area
(BA) 1 and densely so with BA 3b, and projects to PV, BA 7b, insular cortex, amygdala and hippocampus. PV connects densely with BA 5 and the premotor cortex.
S2 is colored green and the insular cortex brown in the top right image (coronal section) of the human brain. SS1 is green in the top left, and the supplementary somatosensory area is green in the bottom left.
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• Brodmann area 5 is one of Brodmann's cytologically
defined regions of the brain. It is involved in somatosensory processing and association.
• Brodmann area 5 is part of the parietal
h
l cortex in the h
human brain. It is situated immediately posterior to the primary somatosensory areas (Brodmann areas 3, 1, and 2), and anterior to Brodmann area 7.
Astereognosis is the inability to identify an object by touch without visual input. It is a form of tactile
agnosia in which an individual is unable to identify objects by handling them, despite intact sensation . With the absence of vision (i.e. eyes closed), an individual with astereognosis is unable to identify what i l d i th i h d A
is placed in their hand . As opposed to agnosia, when dt
i
h
the object is observed visually, one should be able to successfully identify the object.
Astereognosis is associated with lesions of the parietal lobe or dorsal column or parieto‐temporo‐occipital lobe (posterior association areas) of either the right or left hemisphere of the cerebral cortex
Brodmann area 40, or BA40, is part of the parietal
cortex in the human brain. The inferior part of BA40 is in the area of the supramarginal gyrus, which lies at the posterior end of the lateral fissure, in the inferior lateral part of the parietal lobe.
It is bounded approximately by the intraparietal sulcus, the inferior postcentral sulcus, the posterior subcentral
sulcus and the lateral sulcus. Cytoarchitecturally it is bounded caudally by the angular area 39 (H), rostrally
and dorsally by the caudal postcentral area 2, and ventrally by the subcentral area 43
ventrally by the subcentral
area 43 and the superior and the superior
temporal area 22 (Brodmann‐1909).
Cytoarchitectonically defined subregions of rostral BA40/the supramarginal gyrus are PF, PFcm, PFm, PFop, and PFt. Area PF is the homologue to macaque area PF, part of the mirror neuron system
mirror neuron system, and active in humans during imitation.
The supramarginal gyrus part of Brodmann area 40 is the region in the inferior parietal lobe that is involved in reading both in regards to meaning and phonology.
•
•
Brodmann area 7 is one of Brodmann's
cytologically defined regions of the brain. It is involved in locating objects in space. It serves as a point of convergence between vision
and proprioception to determine where objects are in relation to parts of the body.
Brodmann area 7 is part of the parietal
cortex in the human brain. Situated posterior to the primary somatosensory cortex
(Brodmann areas 3, 1 and 2), and superior to visual cortices (Brodmann areas 17, 18 and 19), this region is believed to play a role in visuo motor coordination (e.g., in reaching to visuo‐motor coordination
(e g in reaching to
grasp an object).
Brodmann area 39, or BA39, is part of the parietal cortex in the human brain. BA39 encompasses the angular gyrus, lying near to the junction of temporal, occipital and parietal lobes.
This area is also known as angular area 39 (H). It corresponds to the angular gyrus surrounding the caudal tip of the superior temporal sulcus. Dorsally it is bounded approximately by the intraparietal sulcus. Cytoarchitecturally it is bounded rostrally by the supramarginal area 40
area 40 (H), dorsally and caudally by the (H) dorsally and caudally by the
peristriate area 19, and ventrally by the occipitotemporal area 37 (H) (Brodmann‐1909).
Damage to Brodmann area 39 plays a role in semantic aphasia. It was regarded by Alexander Luria as a part of the temporo‐parieto‐occipital area, which includes Brodmann area 40, Brodmann area 19, and Brodmann
area 37.
More recent fMRI studies have shown that humans have similar functional regions in and around the intraparietal sulcus and parietal‐occipital junction. The human 'parietal eye fields' and 'parietal reach region', equivalent to LIP and MIP in the monkey, also appear to be organized in gaze‐centered coordinates so that their goal‐related activity is 'remapped' when the eyes move. Both the left and right parietal systems play a determining role in self transcendence, the personality trait measuring predisposition to spirituality This lobe is divided into two hemispheres‐ left and right. The left hemisphere plays a more prominent role for right handers and is involved in symbolic functions in language and mathematics. Meanwhile, the right hemisphere the right hemisphere plays a more prominent role for left handers and is specialised to carry out images and understanding of maps i.e. spatial relationships. Damage to the right hemisphere of this lobe results in the loss of imagery, visualization of spatial relationships and neglect of left side space and left side of the body. Even drawing may be neglected from the left side. Damage to the left hemisphere of this lobe will result in problems in mathematics, long reading, writing and understanding symbols. The parietal association cortex enables individuals to read, write, and solve mathematical problems. The sensory inputs from the right side go to the left side and vice‐versa.
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Clinical significance
Lesions affecting the primary somatosensory cortex produce characteristic symptoms including: agraphesthesia, astereognosia, loss of vibration, proprioception and fine touch (because the third‐order neuron of the medial‐lemniscal pathway cannot synapse in the cortex). It can also produce hemineglect, if it affects the non‐dominant hemisphere.
It could also reduce nociception, thermoception and crude touch, but since information from the spinothalamic tract is interpreted mainly by other areas of the brain (insular cortex and cingulate gyrus), it is not as relevant as the other symptoms.
Analgesia, this is the difficulty perceiving and processing pain; thought to underpin some forms of self injury.[
Tactile agnosia Impaired ability to recognize or identify Tactile agnosia
objects by touch alone.
Agraphesthesia is a disorder of directional cutaneous
kinesthesia or a disorientation in cutaneous space. It is a difficulty recognizing a written number or letter traced on the palm of one
the palm
of one'ss hand after parietal
hand after parietal damage
Astereognosis or Somatosensory agnosia is connected to tactile sense ‐ that is, touch. Patient finds it difficult to recognize objects by touch based on its texture, size and weight. However, they may be able to describe it verbally or recognize same kind of objects from pictures or draw pictures of them. Thought to be connected to lesions or damage in somatosensory cortex.
Hemispatial neglect, also called hemiagnosia, hemineglect, unilateral neglect, spatial neglect, unilateral visual inattention, hemi‐inattention or neglect syndrome is a neuropsychological
condition in which, after damage to one hemisphere of the brain, a deficit in attention to and awareness of one side of space is observed. It is defined by the p
y
inability for a person to process and perceive stimuli on one side of the body or environment that is not due to a lack of sensation. Hemispatial neglect is very commonly contralateral to the damaged hemisphere, but instances of ipsilesional
neglect (on the same side as the lesion) have been reported
An example of a
neglect syndrome.
Hemispatial neglect is most neglect frequently associated with a lesion of the right the right parietal lobe
Self-portraits by an
artist after damage to
his right posterior
parietal cortex.
Gerstmann's syndrome is associated with lesion to the dominant (usually left) parietal lobe.
Balint's syndrome is associated with bilateral lesions. The syndrome of hemispatial neglect is usually associated with large deficits of attention of the non‐
g
dominant hemisphere. Optic ataxia is associated with difficulties reaching toward objects in the visual field opposite to the side of the parietal damage. Some aspects of optic ataxia have been explained in terms of the functional organization.
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Gerstmann syndrome is a neurological disorder that is characterized by In children
a constellation of symptoms that suggests the presence of a lesion in a particular area of the brain.
Gerstmann syndrome is characterized by four primary symptoms:
►Dysgraphia/agraphia: deficiency in the ability to write ► Dyscalculia/acalculia: difficulty in learning or comprehending mathematics ► Finger agnosia: inability to distinguish the fingers on the hand ► Left‐right disorientation Causes
This disorder is often associated with brain lesions in the dominant (usually left) hemisphere including the angular and supramarginal gyri near the temporal and parietal lobe junction. There is significant debate in the scientific literature as to whether Gerstmann Syndrome truly represents a unified, theoretically motivated syndrome. Thus its diagnostic utility has been questioned by neurologists and neuropsychologists alike. The angular gyrus is generally involved in translating visual patterns of letter and words into meaningful information, such as is done while reading.
In adults
In adults, the syndrome may occur after a stroke or in association with damage to the parietal lobe. In addition to exhibiting the above symptoms, many adults also experience aphasia, which is a difficulty in expressing oneself when speaking, in understanding speech, or in reading and writing.
There are few reports of the syndrome, sometimes called Developmental Gerstmann
Developmental Gerstmann syndrome, in children. The cause is not known. Most cases are identified when children reach school age, a time when they are challenged with writing and math exercises. Generally, children with the disorder exhibit poor handwriting and spelling skills, and difficulty with math functions, i l di
including adding, subtracting, multiplying, and dividing.
ddi
bt ti
lti l i
d di idi An inability A i bilit
to differentiate right from left and to discriminate among individual fingers may also be apparent. In addition to the four primary symptoms, many children also suffer from constructional apraxia, an inability to copy simple drawings. Frequently, there is also an impairment in reading. Children with a high level of intellectual functioning as well as those with brain damage may be affected with the disorder.
Bálint's syndrome
is an uncommon and incompletely understood triad of severe neuropsychological impairments involving space representation (visuospatial processing). Its three major components are 1) Simultanagnosia, i.e., the inability to perceive the visual field as a whole, 2) Ocular apraxia, a deficit of visual scanning, and Apraxia—inability to carry out familiar movements when asked to do so
3) Optic ataxia, an impairment of pointing and reaching under visual guidance. Acalculia
The syndrome was named in 1909 for the Austro‐Hungarian neurologist Rezső Bálint who had been the first to identify it. Since it represents impairment of both visual and language functions, it is a significant disability that can affect the patient's safety even in ,
p
p
g
one's own home environment, and can render the person incapable of maintaining employment. Lack of awareness of this syndrome may lead to a misdiagnosis and resulting inappropriate or inadequate treatment. Therefore, clinicians should be familiar with Bálint's syndrome and its various etiologies.
Balint's syndrome occurs most often with an acute onset as a consequence of multiple bilateral strokes. The most frequent cause of complete Balint's syndrome is said by some to be sudden and severe hypotension, resulting in bilateral borderzone infarction in the occipito‐parietal region. More rarely, cases of progressive Balint's syndrome have been found in degenerative disorders such as Alzheimer's disease or certain other traumatic brain injuries at the border of the parietal and the occipital lobes of the brain.
7/23/2011
NEUROPSYCHIATRY
226
415703 Cognitive Neuropsychology
Week 6:
Body Schema Disturbance
The Temporal lobes
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
7/23/2011
NEUROPSYCHIATRY
227
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Main Objectives:
1. The The temporal lobes and their functions
temporal lobes and their functions
2. The Auditory System
3. Auditory Perception and Auditory Cortical Organization
4 The
4.
The two Stream Hypothesis: The Dorsal stream, two Stream Hypothesis: The Dorsal stream
“Where or How” and The Ventral Stream, “What”
5. Deep brain structures in Temporal lobe, e.g., Limbic brain structures and their functions
6. Neuropsychology of the Temporal lobes.
The superior temporal gyrus
The superior temporal gyrus is one of three (sometimes two) gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear.
The superior temporal gyrus is bounded by:
the lateral sulcus above; the superior temporal sulcus below; an imaginary line drawn from the preoccipital
notch to the lateral sulcus posteriorly. The superior temporal gyrus contains several important structures of the brain, including:
Brodmann areas 41 41 and and 42
42, marking the location of the primary auditory cortex, the cortical region responsible for the sensation of sound
Wernicke's area, Brodmann
Brodmann 22
22p
p, an important region for the processing of speech so that it can be understood as language. The temporal lobe
is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain.
The temporal lobe is involved in auditory perception and is home to the primary auditory cortex. It is also important for the processing of semantics in both speech and vision. The temporal lobe contains the hippocampus and plays a key role in the formation of long‐term memory.
The superior temporal gyrus includes an area (within the Sylvian fissure) where auditory signals from the cochlea (relayed via several subcortical nuclei) first reach the cerebral cortex. This part of the cortex (primary auditory cortex) is involved in hearing. Adjacent areas in the superior, posterior and lateral parts of the temporal lobes are involved in high‐level auditory processing. In humans this includes speech, for which the left temporal lobe in particular seems to be specialized. Wernicke's area, which spans the region between temporal and parietal lobes, plays a key role (in tandem with Broca's area, which is in the frontal lobe). The functions of the left temporal lobe are not limited to low‐level perception but extend to comprehension, naming, verbal memory and other language functions.
The underside (ventral) part of the temporal cortices appear to be involved in high‐level visual processing of complex stimuli such as faces (fusiform gyrus) and scenes (parahippocampal gyrus). Anterior parts of this ventral stream for visual processing are involved in object perception and recognition.
The medial temporal lobes (near the Sagittal plane that divides left and right cerebral hemispheres) are thought to be involved in episodic/declarative memory. Deep inside the medial temporal lobes lie the hippocampi, which are essential for memory function ‐ particularly the transference from short to long term memory and control of spatial memory and behavior. Damage to this area typically results in anterograde amnesia.
Brain mechanisms
for auditory
functions
(Hearing)
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Auditory Perception or Hearing
(or audition; "auditory" or "aural") is the ability to perceive sound by detecting vibrations
through an organ such as the ear. It is one of the traditional five senses. The inability to hear is called deafness.
In humans and other vertebrates, hearing is performed primarily by the auditory system: vibrations are detected by the ear and transduced into nerve impulses that are perceived by the brain (primarily in the temporal lobe). Like touch, audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation.
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The primary auditory The primary auditory cortex is the region of the brain that is responsible for the processing of auditory (sound) information. Corresponding roughly with Brodmann areas 41 and 42
and 42, it is located on the temporal lobe, and performs the basics of hearing—pitch and volume. Besides receiving input from the ear and lower centers of the brain, the primary auditory cortex also transmits signals back to these areas.
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Function of Primary auditory cortex
As with other primary sensory cortical areas, auditory sensations reach perception only if received and processed by a cortical area. Evidence for this comes from lesion studies in human patients who have sustained damage to cortical areas through tumors or strokes, or from animal experiments in which cortical areas were deactivated by cooling or locally applied drug treatment. Damage to the Primary Auditory Cortex in humans leads to a loss of any awareness of sound, but an ability to react reflexively to sounds remains as there is a great deal of subcortical processing in the auditory brainstem and midbrain.
Neurons in the auditory cortex are organized according to the frequency of sound to which they respond best. Neurons at one end of the auditory cortex respond best to low frequencies; neurons at the other respond best to high frequencies
frequencies; neurons at the other respond best to high frequencies. There are multiple auditory areas (much like the multiple areas in the visual cortex), which can be distinguished anatomically and on the basis that they contain a complete "frequency map." The purpose of this frequency map (known as a tonotopic map) is unknown, and is likely to reflect the fact that the cochlea is arranged according to sound frequency. The auditory cortex is involved in tasks such as identifying and segregating auditory "objects" and identifying the location of a sound in space.
Human brain scans have indicated that a peripheral bit of this brain region is active when trying to identify musical pitch. Individual cells consistently get excited by sounds at specific frequencies, or multiples of that frequency.
The auditory cortex is an important yet ambiguous part of the hearing process. When the sound pulses pass into the cortex the specifics of what exactly takes place are unclear. Distinguished scientist and musician James Beament puts it into perspective when he writes, “The cortex is so complex that the most we may ever hope for is to understand it in principle, since the evidence we already have suggests that no two cortices work in precisely the same way."
In hearing process, multiple sounds are being absorbed simultaneously. The role of the auditory system is to decide which components form the sound link. Many have surmised that this linking is based on location of sounds; however, there are numerous distortions h hi li ki i b d
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i
f
d h
h
di
i
of sound when reflected off different mediums, which makes this thinking unlikely. Instead, the auditory cortex forms groupings based on other more of the reliable, fundamentals. In music for example, this would include harmony, timing, and pitch.
The primary auditory cortex lies in the posterior half of the superior temporal gyrus and also dives into the lateral sulcus as the transverse temporal gyri (also called Heschl's gyri
).
The primary auditory cortex is located in the temporal lobe. There are additional areas of the human cerebral cortex that are involved in processing sound, in the frontal and parietal lobes.
Brodmann area 41 is also known as the anterior transverse temporal area 41 (H). It is a subdivision of the cytoarchitecturally‐defined temporal region of cerebral cortex, occupying the anterior transverse temporal gyrus (H) in the bank of the lateral sulcus on the dorsal surface of the temporal lobe. Brodmann area 41 is bounded medially by the area 42
42 (H).
parainsular area 52 (H) and laterally by the posterior transverse temporal area Brodmann area 42 is also known as the posterior transverse temporal area 42 (H). It is a subdivision of the cytoarchitecturally‐defined temporal region of cerebral cortex, located in the bank of the lateral sulcus on the dorsal surface of the temporal lobe. Brodmann area 42 is bounded medially by the anterior transverse temporal area 41 (H) and laterally by the superior temporal area 22
superior temporal area 22.
The primary auditory cortex is tonotopically organized, which means that neighboring cells in the cortex respond to neighboring frequencies. This is a fascinating function which has been preserved throughout most of the audition circuit. This area of the brain is thought to identify the fundamental elements of music, such as pitch
pitch and loudness. This makes sense, as this is the area which and loudness
receives direct input from the medial geniculate nucleus of the thalamus. The secondary auditory cortex has been indicated in the processing of “harmonic, melodic and rhythmic patterns.” The tertiary auditory cortex
supposedly integrates everything into the overall experience of music
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Broca's area is a region of the hominid brain
with functions linked to speech production.
The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal gyrus of the brain. Since then, the approximate region he identified has become known as Broca’s area, and the deficit in language production as Broca’s aphasia. Broca’s area is now typically defined in terms of the pars opercularis
typically defined in terms of the pars opercularis
and pars triangularis of the inferior frontal gyrus, represented in Brodmann
Brodmann’s
’s cytoarchitectonic map as areas 44
as areas 44 and and 45
45.. Studies of chronic aphasia have implicated an essential role of Broca’s area in various speech and language functions. Further, functional MRI studies have also identified activation patterns in Broca’s area associated with various language tasks. However, slow destruction of the Broca's area by brain tumors can leave speech relatively intact suggesting its functions can shift to nearby areas in the brain.
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Two Streams hypothesis::
Two Streams hypothesis
As visual information passes forward through the visual hierarchy, the complexity of the neural representations increase. Whereas a V1 neuron may respond selectively to a line segment of a particular orientation in a particular retinotopic
location, neurons in the lateral occipital complex respond selectively to complete object (e.g., a figure drawing), and neurons in visual association cortex may respond selectively to human faces, or to a particular object.
Along with this increasing complexity of neural representation may come a level of specialization of processing into two distinct pathways: the dorsal stream and the ventral stream (the Two Streams hypothesis, first proposed by Ungerleider
the ventral stream (the Two Streams hypothesis, first proposed by Ungerleider
and Mishkin in 1982). The dorsal stream, commonly referred to as the The dorsal stream, commonly referred to as the "where" "where" stream, is involved in stream, is involved in spatial attention (covert and overt), and communicates with regions that control eye movements and hand movements. More recently, this area has been called the "how" the "how" stream to emphasize its role in guiding behaviors to spatial locations. stream to emphasize its role in guiding behaviors to spatial locations. The ventral stream, commonly referred as the "what" stream
The ventral stream
"what" stream, is involved in the recognition, identification and categorization of visual stimuli.
However, there is still much debate about the degree of specialization within these two pathways, since they are in fact heavily interconnected
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The dorsal stream (Parietal lobe) for “Where”
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The ventral stream is associated with object recognition and form representation. It has strong connections to the medial temporal lobe (which stores long‐
term memories), the limbic system (which controls emotions), and the dorsal stream
(which deals with object locations and motion).
The ventral stream gets its main input from the parvocellular (as opposed to magnocellular) layer of the lateral geniculate nucleus of the thalamus. These neurons project to V1 sublayers 4Cβ, 4A, 3B and 2/3a successively. From there, the ventral pathway goes through V2 and V4 to areas of the inferior temporal lobe: PIT (posterior inferotemporal), CIT (central inferotemporal), and AIT (anterior inferotemporal). Each visual area contains a full representation of visual space. That is, it contains neurons
whose receptive fields together represent the entire visual field. Visual information enters the ventral stream through the primary visual cortex
h
l
h
h h
i
i l
and travels through the rest d
l h
h h
of the areas in sequence.
Moving along the stream from V1 to AIT, receptive fields increase their size, latency, and the complexity of their tuning.
All the areas in the ventral stream are influenced by extraretinal factors in addition to the nature of the stimulus in their receptive field. These factors include attention, working memory, and stimulus salience. Thus the ventral stream does not merely provide a description of the elements in the visual world—it also plays a crucial role in judging the significance of these elements.
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Brain mechanisms
for olfaction
(Smell), the nose
brain or
“Rhinencephalon”
and
d associated
i t d
limbic structures
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The limbic system
The limbic system (or Paleomammalian brain) is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The limbic system operates by influencing the endocrine system and the autonomic nervous system. It is highly interconnected with the nucleus accumbens, the brain's pleasure center, which plays a role in sexual arousal and the "high" derived from certain recreational drugs. These responses are heavily modulated by dopaminergic projections from the limbic system. In 1954, Olds
and Milner found that rats with metal electrodes implanted into their nucleus d Mil
f
d th t t ith
t l l t d i l t d i t th i
l
accumbens as well as their septal nuclei repeatedly pressed a lever activating this region, and did so in preference to eating and drinking, eventually dying of exhaustion.
The limbic system is also tightly connected to the prefrontal cortex. Some scientists contend that this connection is related to the pleasure obtained from solving problems. To cure severe emotional disorders, this connection was sometimes surgically severed, a procedure of psychosurgery, called a prefrontal lobotomy (this is actually a misnomer). Patients who underwent this procedure often became passive and lacked all motivation.
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The limbic system is the set of brain structures that forms the inner border of the cortex. The cortical components generally have fewer layers than the classical 6‐layered neocortex, and are usually classified as allocortex
or archicortex.
The limbic system includes many structures in the cerebral pre‐cortex and sub‐cortex of the brain. The term has been used within psychiatry and neurology, although its exact role and definition have been revised considerably since the term was introduced.
The following structures are, or have been considered to be, part of the limbic system:
Hippocampus and associated structures: Hippocampus:: Required for the formation of long‐term memories and implicated in maintenance of Hippocampus
cognitive maps for navigation. Amygdala:: Involved in signaling the cortex of motivationally significant stimuli such as those related Amygdala
to reward and fear in addition to social functions such as mating. Fornix: carries signals from the hippocampus to the mammillary bodies and septal nuclei. Mammillary body:: Important for the formation of memory; Mammillary body
Septal nuclei: Located anterior to the interventricular septum, the septal nuclei provide critical interconnections Limbic lobe
Parahippocampal gyrus: Plays a role in the formation of spatial memory Cingulate gyrus: Autonomic functions regulating heart rate, blood pressure and cognitive and attentional processing Dentate gyrus: thought to contribute to new memories and to regulate happiness. In addition, these structures are sometimes also considered to be part of the limbic system:
Entorhinal cortex: Important memory and associative components. Piriform cortex: The function of which relates to the olfactory system. Fornicate gyrus: Region encompassing the cingulate, hippocampus, and parahippocampal gyrus Nucleus accumbens: Involved in reward, pleasure, and addiction
Orbitofrontal cortex: Required for decision making. Clinical Correlates of Limbic System:
Amygdala ,,,,,, Fear, Anxiety, Aggressive, Violence, Rage
Hippocampus… Episodic Memories
Cingulate Gyrus …. Instinctive Behaviours, Parenting,
Social bonding, Moral reasoning,
Delayed alternating tasks
Delayed
alternating tasks
Septal Nucleus … Docility, Hypothalamus ……ANS, Endocrine, Drive, Motivation
Mammillary Body….. Memory retrieval, recall
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Clinical Correlates of Limbic System:
Kluver-Bucy Syndrome:
Fearlessness. Hyperphagia, Hypersexuality,
Psychic Blindness
Korsakoff’s Psychosis: Confabulation
Amnesia: (Retrograde & Anterograde Amnesia)
Temporal Lobe Epilepsy:
Stress, Post-traumatic Stress Disorders
Anxiety, Fear & Phobia
Panic Attacks, Emotional Depression
Obsessive- Compulsive Disorders
Abnormal Aggressive & Violence Behaviours
Paranoid,
Delusion, Schizophrenia
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What is Klüver-Bucy Syndrome?
Klüver‐Bucy syndrome is a rare behavioral impairment that is associated with damage to both of the anterior temporal lobes of the brain. It causes individuals to put objects in their mouths and engage in inappropriate sexual behavior. Other symptoms may include visual agnosia (inability to visually recognize objects), loss of normal fear and anger responses, memory loss, distractibility, seizures, and dementia. The disorder may be associated with herpes encephalitis and trauma, which can result in brain damage In humans: (Klüver-Bucy syndrome)
People with lesions in their temporal lobes (a bilateral lesion) show similar behaviors. They may display oral or tactile exploratory behavior (socially inappropriate licking or touching); hypersexuality; bulimia; memory disorders; flattened emotions; and an inability to recognize objects or inability to recognize faces.
The full syndrome rarely, if ever, develops in humans. However, parts of it are often noted in patients with extensive bilateral temporal damage caused by herpes or other encephalitis, dementias of degenerative (Alzheimer's disease, Pick's Disease) or post‐traumatic etiologies or cerebrovascular disease.
Klüver-Bucy syndrome is a behavioral disorder that occurs when both the right and left medial temporal lobes of the brain
malfunction. The amygdala has been a particularly implicated brain region in the pathogenesis of this syndrome
The syndrome is named for Heinrich Klüver and Paul Bucy, who removed the temporal lobe bilaterally in rhesus monkeys in an attempt to determine its function.
This caused the monkeys to develop visual agnosia, emotional changes, altered sexual behavior, and oral tendencies.
Though the monkeys could see, they were unable to recognize even previously g
y
,
y
g
p
y
familiar objects, or their use. They would examine their world with their mouths instead of their eyes ("oral tendencies")
("oral tendencies") and developed a desire to explore everything ("hypermetamorphosis").
("hypermetamorphosis").
Their overt sexual behavior increased dramatically ("
("hypersexualism
hypersexualism""), and the monkeys indulged in indiscriminate sexual behavior including masturbation,
heterosexual acts and homosexual acts
heterosexual acts and homosexual acts.
Emotionally, the monkeys became dulled, and their facial expressions and vocalizations became far less expressive. They were also less fearful
less fearful of things that would have instinctively panicked them in their natural state, such as humans or snakes. Even after being attacked by a snake, they would willingly approach it again. This aspect of change was termed “Placidity”
“Placidity”.
The fusiform
The fusiform gyrus is part of the temporal lobe in Brodmann Area 37. It is also known as the (discontinuous) occipitotemporal gyrus. [1] Other sources have the fusiform gyrus above the occipitotemporal gyrus and underneath the parahippocampal gyrus.[2]
Function
There is still some dispute over the functionalities of this area, but there is relative consensus on the following:
►Processing of color information ► Face and body recognition ( Fusiform face area) ► Word recognition ► Number recognition
► Within‐category identification g y
Medial surface of left cerebral hemisphere. (Fusiform gyrus visible near bottom)
Some researchers think that the fusiform gyrus may be related to the disorder known as prosopagnosia, or face blindness. Research has also shown that the fusiform face area, the area within the fusiform gyrus, is heavily involved in face perception but only to any generic within‐category identification which is shown to be one of the functions of the fusiform gyrus.
Fusiform gyrus has also been involved in the perception of emotions in facial stimuli.
Recent research has seen activation of the fusiform gyrus during subjective grapheme‐color perception in people with synaesthesia
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The fusiform
The fusiform face area (FFA) is a part of the human visual system which might be specialized for facial Fusiform Face Area (FFA)
recognition, although there is some evidence that it also processes categorical information about other objects, particularly familiar ones.
Localization
The FFA is located in the ventral stream on the ventral surface of the temporal lobe on the fusiform gyrus. It is adjacent to the parahippocampal place area and near the putative extrastriate body area. It is in a slightly different place for each human and displays some lateralization, usually being larger in the right hemisphere.
The FFA was discovered and continues to be investigated in humans using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies. Usually, a participant views images of faces, objects, places, bodies, scrambled faces, scrambled objects, scrambled places and scrambled bodies. This is called a functional localizer. Comparing the neural response between faces and scrambled faces will reveal areas that are face‐
responsive, while comparing cortical activation between faces and objects will reveal areas that are face‐selective.
Functional role
The human FFA was first described by Justine Sergent in 1992 and more recently by Nancy Kanwisher in 1997 who proposed that the existence of the FFA is evidence for domain specificity in the visual system. More recently, it has proposed that the existence of the FFA is evidence for domain specificity
in the visual system More recently it has
been suggested that the FFA processes more than just faces. Some groups, including Isabel Gauthier and others, maintain that the FFA is an area for recognizing fine distinctions between well‐known objects. Gauthier et al. tested both car and bird experts, and found some activation in the FFA when car experts were identifying cars and when bird experts were identifying birds. A recent paper by Kalanit Grill‐Spector et al. also suggests that processing in the FFA is not exclusive to faces, although an erratum was later published which brought to light some errors.The debate about the functional role of the FFA is ongoing.
A 2009 magnetoencephalography study found that objects incidentally perceived as faces, an example of pareidolia, evoke an early (165 ms) activation in the FFA, at a time and location similar to that evoked by faces, whereas other common objects do not evoke such activation. This activation is similar to a slightly earlier peak at 130 ms seen for images of real faces. The authors suggest that face perception evoked by face‐like objects is a relatively early process, and not a late cognitive reinterpretation phenomenon.
N & NJ Kotchabhakdi 2008
Prosopagnosia (Greek: "prosopon" = "face", "agnosia" = "inabilty to recognise/identify familiar people or objects") is a disorder of face perception
where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact. The term originally referred to a condition following acute brain damage, but a congenital form of the disorder has been proposed, which may be inherited by about 2.5% of the population. The specific brain area usually associated with prosopagnosia is the fusiform gyrus.
Few successful therapies have so far been developed for affected people, although individuals often learn to use 'piecemeal' or 'feature by feature' recognition strategies. This may involve secondary clues such as clothing, gait, hair color, body shape, and voice. Because the face seems to function as an important identifying feature in memory, it can also be difficult for people with this condition to keep track of information about people, and socialize normally with others.
Some also use the term prosophenosia, which refers to the inability to recognize faces following extensive damage of both occipital and temporal lobes
260
415703 Cognitive Neuropsychology
Week 6:
The Frontal lobes
Naiphinich Kotchabhakdi, Ph.D.
Director, Salaya Stem Cell R & D Project,
Research Center for Neuroscience,
Institute of Molecular Biosciences,
Mahidol University Salaya Campus,
999 Phutthamonthol 4 Road, Salaya, Phutthamonthol,
Nakornpathom 73170 Thailand
Email: scnkc@mahidol.ac.th or naiphinich@gmail.com
Web: www.neuroscience.mahidol.ac.th
Main Objectives:
1.
2.
3.
4.
5
5.
The The Frontal lobes and their functions
Frontal lobes and their functions
The Motor System
Motor Cortical Organization in the Frontal Lobe
The Prefrontal cortex
The
The Frontal lobes and higher or executive brain Frontal lobes and higher or executive brain
functions
6. Deep brain structures in Frontal lobe, e.g., Limbic brain structures and their functions
7. Neuropsychology of the Frontal lobes and executive brain function disorders.
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The Frontal lobe is an area in the brain of humans and other Frontal lobe Anatomy
mammals, located at the front of each cerebral hemisphere and positioned anterior to (in front of) the parietal lobes and superior and anterior to the temporal lobes (i.e. directly behind the forehead or "temple"). It is separated from the parietal lobe by the post‐central gyrus primary motor cortex, which controls voluntary movements of specific body parts associated with the precentral gyrus posteriorly, inferiorly by lateral sulcus[slyvian] which separates it from the temporal lobe, superiorly by the superior margin of the hemisphere and anteriorly by the frontal pole.
The frontal lobe contains most of the dopamine‐sensitive neurons in the reward, attention, cerebral cortex. The dopamine system is associated with reward, attention, short‐‐term memory tasks, planning, and drive
short
term memory tasks, planning, and drive. Dopamine tends to limit and select sensory information arriving from the thalamus to the fore‐brain. A report from the National Institute of Mental Health says a gene variant that reduces dopamine activity in the prefrontal cortex is related to poorer performance and inefficient functioning of that brain region during working memory tasks, and to slightly increased risk for schizophrenia.
On the lateral surface of the human brain, the central sulcus separates the frontal lobe from the parietal lobe. The lateral sulcus separates the frontal lobe from the temporal lobe.
The frontal lobe can be divided into a lateral, polar, orbital (above the orbit; also called basal or ventral), and medial part. Each of these parts consists of particular gyri:
Pyramidal motor system: Corticospinal tracts is a collection of axons that travel between the cerebral cortex
of the brain and the spinal cord.
The corticospinal tract mostly contains motor axons. It actually consists of two separate tracts in the spinal cord: the lateral corticospinal tract and the anterior corticospinal tract. An understanding of these tracts leads to an understanding of why for the most part, one side of the body is controlled by the opposite side of the brain.
The corticobulbar tract is also considered to be a The corticobulbar
is also considered to be a
pyramidal tract, though it carries signals to motor neurons of the cranial nerve nuclei, rather than the spinal cord.
The neurons of the corticospinal tracts are referred to as pyramidal neurons. The name comes from the shape of the corticospinal tracts, which somewhat resemble pyramids as they pass through the medulla.
The corticospinal tract is concerned specifically with discrete voluntary skilled movements, especially of the distal parts of the limbs. (Sometimes called "fractionated" movements)
∆ Lateral part: : Precentral gyrus, lateral part of the superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus.
∆ Polar part: Transverse frontopolar gyri, frontomarginal gyrus.
∆ Orbital part: Orbital part: Lateral orbital gyrus, anterior orbital gyrus, posterior orbital gyrus, medial orbital gyrus, gyrus rectus.
∆ Medial part: ∆ Medial part: di l
Medial part of the superior frontal gyrus, cingulate gyrus.
The gyri are separated by sulci. E.g., the precentral gyrus is in front of the central sulcus, and behind the precentral sulcus. The superior and middle frontal gyri are divided by the superior frontal sulcus. The middle and inferior frontal gyri are divided by the inferior frontal sulcus.
In humans, the frontal lobe reaches full maturity around only after the 20s, marking the cognitive maturity associated with adulthood.
Dr. Arthur Toga, a UCLA professor of neurology, found increased myelin in the frontal lobe white matter of young adults compared to that of teens. A typical onset of schizophrenia in early adult years correlates with poorly myelinated and thus inefficient connections between cells in the fore‐brain
The motor pathway
The corticospinal tract originates from pyramidal cells in layer V of the cerebral cortex. About half of its fibres arise from the primary motor cortex. Other contributions come from the supplementary motor area, premotor cortex, somatosensory cortex, parietal lobe, and cingulate gyrus. The average fiber diameter is in the region of 10μm; around 3% of fibres are extra‐large (20μm) and arise from Betz cells, mostly in the leg area of the primary motor cortex.
Upper motor neurons
The neuronal cell bodies in the motor cortex, together with their axons that travel down through the brain stem and spinal cord are commonly referred to as upper motor neurons. It should be noted however, that they do not project to muscles, and thus the term 'motor neuron' is somewhat misleading.
Anatomy of the motor cortex
The motor cortex can be divided into four main parts:
∆ the primary motor cortex (or M1, B
Broadman area #4), responsible for generating the neural impulses controlling execution of movement
and the secondary motor cortices, including ∆ the posterior parietal cortex, responsible for transforming ∆ visual information into motor commands
∆ the premotor cortex, (B
∆ Broadman areas #6, 8, 9,10) responsible for motor guidance of movement and control of proximal and trunk muscles of the body
∆ and the supplementary motor area (or SMA), responsible ∆ for planning and coordination of complex movements such as those requiring two hands.
Other brain regions outside the cortex are also of great importance to motor function, most notably the cerebellum and subcortical motor nuclei.
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The extrapyramidal
The extrapyramidal system is a neural network located in the brain that is part of the motor system involved in the coordination of movement. The system is called "extrapyramidal" to distinguish it from the tracts of the motor cortex that reach their targets by traveling through the "pyramids" of the medulla. The pyramidal pathways (corticospinal and some corticobulbar tracts) may directly innervate motor neurons of the spinal cord or brainstem (anterior (ventral) horn cells or certain cranial nerve nuclei), whereas the extrapyramidal system centers around the modulation and regulation (indirect control) of anterior (ventral) horn cells.
Extrapyramidal tracts are chiefly found in the reticular formation of the pons and medulla, and target neurons in the spinal cord involved in reflexes, locomotion, complex movements, and postural control. These tracts are in turn modulated by various parts of the central nervous system, including the nigrostriatal pathway, the basal ganglia, the cerebellum, the vestibular nuclei, and different sensory areas of the cerebral cortex. All of these regulatory components can be considered part of the extrapyramidal system, in that they modulate motor activity without directly innervating motor neurons.
Corticospinal tract damage
Damage to the descending motor pathways anywhere along the trajectory from the cerebral cortex to the lower end of the spinal cord gives rise to a set of symptoms called the "upper motor neuron syndrome". A few days after the injury to the upper motor neurons a pattern of motor signs and symptoms appears, including spasticity, the decreased vigor (and increased threshold) of superficial reflexes, a loss of the ability to perform fine movements, and an extensor plantar response known as the Babinski sign.[
The frontal eye fields
The frontal eye fields (FEF) is a region located in the premotor cortex, which is part of the frontal cortex of the primate brain.
Function
The cortical area called frontal eye fields (FEF) plays an important role in the control of visual attention and eye movements. Electrical stimulation in the FEF elicits saccadic eye movements. The FEF have a topographic structure and represents saccade targets in retinotopic coordinates.
The frontal eye field is reported to be activated during the initiation of eye movements, such as voluntary saccades and pursuit eye movements. There is also evidence that it plays a role in purely sensory processing and that it belongs to a “fast
plays a role in purely sensory processing and that it belongs to a fast brain
brain” system system
through a superior colliculus – medial dorsal nucleus – FEF ascending pathway.In
humans, its earliest activations in regard to visual stimuli occur at 45 ms with activations related to changes in visual stimuli within 45–60 ms (these are comparable with response times in the primary visual cortex). This fast brain pathway also provides auditory input at even shorter times starting at 24 ms and being affected by auditory characteristics at 30–60 ms. The FEF constitutes together with the supplementary eye fields (SEF), the intraparietal sulcus (IPS) and the superior colliculus (SC) one of the most important brain areas involved in the generation and control of eye movements, particularly in the direction contralateral to the frontal eye fields' location
direction contralateral to the frontal eye fields' location.
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Brodmann area 8, or BA8, is part of the frontal cortex in the human brain. Situated just anterior to the premotor cortex (BA6), it includes the frontal eye fields (so‐named because they are believed to play an important role in the control of eye movements). Damage to this area, by stroke, trauma or infection, causes tonic deviation of the eyes towards the side of the injury. This finding occurs during the first few hours of an acute event such as cerebrovascular infarct (stroke) or hemorrhage (bleeding).
Brain: Brodmann
Brain: Brodmann area 8
area 8
Distinctive features (Brodmann‐1905): compared to Brodmann area 6‐
1909, area 8 has a diffuse but clearly present internal granular layer (IV); sublayer 3b of the external pyramidal layer (III) has densely distributed medium sized pyramidal cells; the internal pyramidal layer (V) has larger ganglion cells densely distributed with some granule cells interspersed; the external granular layer (II) is denser and broader; cell layers are more distinct; the abundance of cells is somewhat greater.
Other Functions
The area is involved in the management of uncertainty. A functional magnetic resonance imaging study demonstrated that brodmann area 8 activation occurs when test subjects experience uncertainty, and that with increasing uncertainty there is increasing activation.
An alternative interpretation is that this activation in frontal cortex encodes hope, a higher‐order expectation positively correlated with uncertainty.
The limbic system is also tightly connected to the prefrontal cortex
prefrontal cortex.
Some scientists contend that this connection is related to the pleasure obtained from solving problems. To cure severe emotional disorders, this connection was sometimes surgically severed, a procedure of psychosurgery, called a prefrontal lobotomy. Patients who underwent this procedure often became passive and lacked all motivation.
There is circumstantial evidence that the limbic system also provides a custodial function for the maintenance of a healthy conscious state of mind.
Brodmann’s areas 3D
map: Lateral Surface
map: Medial Surface
Brodmann areas for human & non‐
areas for human & non‐human primates
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Brodmann area area 44
44, or BA
, or BA44
44, is part of the frontal
cortex in the human brain. Situated just anterior to premotor cortex (BA6) and on the lateral surface, inferior to BA9.
This area is also known as pars opercularis (of the inferior frontal gyrus), and it refers to a subdivision of the cytoarchitecturally defined frontal region of cerebral cortex. In the human it corresponds approximately to the opercular part Brain: Brodmann area 44
of inferior frontal gyrus (H). Thus, it is bounded caudally by the inferior precentral sulcus (H) and rostrally by the anterior ascending limb of lateral sulcus (H). It surrounds the diagonal sulcus (H). In the depth of the lateral sulcus it borders on the insula Cytoarchitectonically it is bounded caudally and dorsally insula. Cytoarchitectonically
it is bounded caudally and dorsally
by the agranular frontal area 6, dorsally by the granular frontal area 9 and rostrally by the triangular area 45 (Brodmann‐1909). Together with left‐hemisphere BA 45, the left hemisphere. BA 44 comprises Broca's area a region involved in semantic tasks. Some data suggest that BA44 is more involved in phonological and syntactic processing. Some recent findings also suggest the implication of this region in music perception. In 95.5% of right‐
handers and 61.4% of left‐handers, therefore about 90% of the clinical population, speech is lateralised in the left hemisphere. Brodmann area 45
area 45 (BA
BA45
45), ), is part of the frontal
cortex in the human brain. Situated on the lateral surface, inferior to BA9 and adjacent to BA46. This area is also known as pars triangular (of the inferior frontal gyrus). In the human, it occupies the triangular part of inferior frontal gyrus (H) and, surrounding the anterior horizontal limb of lateral sulcus (H), a portion of the orbital part of inferior frontal gyrus (H). Bounded caudally by the anterior ascending limb of lateral sulcus (H), it borders on the insula in the depth of the lateral sulcus. Cytoarchitectonically it is bounded caudally by the opercular area 44 (BA44), rostrodorsally by the middle frontal area 46
(BA46) and ventrally by the orbital area 47 (BA47) (Brodmann‐1909). Together with BA 44 it comprises Broca's area, a region which is active in semantic tasks, such as semantic decision tasks (determining whether a word represents an abstract or a concrete entity) and generation tasks (generating a verb associated with a noun).
The precise role of BA45 in semantic tasks remains controversial. For some researchers, its role would be to to subserve
subserve semantic retrieval or semantic working memory processes. Under this view, BA44 and BA45 would together guide recovery of semantic information and evaluate the recovered information with regards to the criterion appropriate to a given context. A slightly modified account of this view is that activation of BA45 is needed only under controlled semantic retrieval, when strong stimulus‐stimulus associations are absent. For other researchers, BA45's role is not restricted to semantics per se, but to all activities which require task‐relevant representations from among competing representations.
Brain: Brodmann area 45
Brodmann area 47
area 47, or BA
, or BA47
47, is part of the frontal cortex in the human brain. Curving from the lateral surface of the frontal lobe into the ventral (orbital) frontal cortex. It is below areas BA10 and BA45, and beside BA11.
Brain: Brodmann area 47
This area is also known as orbital area 47. In the human, on the orbital surface it surrounds the caudal portion of the orbital sulcus (H) from which it extends laterally into the orbital part of inferior frontal gyrus (H). y oa c ec o ca y it is bounded caudally by the s bou ded cauda y by e
Cytoarchitectonically
triangular area 45, medially by the prefrontal area 11 of Brodmann‐1909, and rostrally by the frontopolar area 10
(Brodmann‐1909).
It incorporates the region that Brodmann identified as "Area 12" in the monkey, and therefore, following the suggestion of Michael Petrides, some contemporary neuroscientists refer to the region as "BA47/12."
BA47 has been implicated in the processing of syntax
in spoken and signed languages, and more recently in musical syntax.
Brodmann area area 9
9, or BA
, or BA9
9, is part of the , frontal cortex in the human brain. It contributes to the dorsolateral prefrontal cortex. Brodmann area 9 refers to a cytoarchitecturally defined portion of the frontal lobe of the guenon (Old world monkeys). Brodmann‐1909 regarded it on the whole as topographically and cytoarchitecturally homologous to the granular frontal area 9 and frontopolar area 10 in the human. Distinctive features (Brodmann‐1905): unlike Brodmann area 6‐1909, area 9 has a distinct internal area 6 1909 area 9 has a distinct internal
granular layer (IV); unlike Brodmann area 6 or Brodmann
area 8‐1909 its internal pyramdal layer (V) is divisible into two sublayers, an outer layer 5a of densely distributed medium sized ganglion cells that partially merges with layer IV, and an inner, clearer, cell‐poor layer 5b; the pyramidal cells of sublayer 3b of the external pyramidal layer (III) are smaller and sparser in distribution; the external granular layer (II) is narrow, with small numbers of sparsely distributed granule cells.
Prefrontal
cortex
The dorsolateral prefrontal cortex (DL‐PFC or DLPFC), Brain: Brodmann area 9
according to a more restricted definition, is roughly equivalent to Brodmann areas 9 and 46. According to a broader definition DL‐PFC consists of the lateral portions of Brodmann areas 9 – 12, of areas 45, 46, and the superior part of area 47.These regions mainly receive their blood supply from the middle cerebral artery. With respect to neurotransmitter systems, there is evidence that dopamine plays a particularly important role in DL‐PFC.
DL‐PFC is connected to the orbitofrontal cortex, and to a variety of brain areas, which include the thalamus, parts of the basal ganglia (the dorsal caudate nucleus), the hippocampus, and primary and secondary association areas of neocortex, including posterior temporal, parietal, and occipital areas.
DL‐PFC is the last area, 45th, to develop myelinate in the human cerebrum
DL‐PFC serves as the highest cortical area responsible for motor planning, organization, and C
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regulation. It plays an important role in the integration of sensory and mnemonic information and the regulation of intellectual function and action. It is also involved in working memory. However, DL‐PFC is not exclusively responsible for the executive functions. All complex mental activity requires the additional cortical and subcortical
circuits with which the DL‐PFC is connected.
Damage to the DL‐PFC can result in the dysexecutive syndrome,[4] which leads to problems with affect, social judgement, executive memory, abstract thinking and intentionality.[
Lucid dream states
More recent research has found a connection between the DL‐PFC and lucid dream states in which executive function is retained
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Brodmann area 10
area 10, or BA
, or BA10 10 is the frontopolar part of the frontal cortex in the human brain. BA10 was originally defined in terms of microscopic cytoarchitecturic traits in autopsy brains; modern functional imaging research cannot directly identify these boundaries and the terms anterior prefrontal, rostral prefrontal cortex
and frontopolar prefrontal cortex are used to refer to the area in the most anterior part of the frontal cortex that approximates to or principally covers BA10.
BA10 is the largest cytoarchitectonic area in the human brain. It has been described as "one of the least well understood regions of the human brain". Present research d
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suggests that it is involved in strategic processes in memory
retrieval and executive function. During human evolution, the functions in this area resulted in its expansion relative to the rest of the brain.
Brodmann area 11
area 11 is one of Brodmann's
cytologically defined regions of the brain. It is involved in planning, reasoning, and decision making.
Brain: Brodmann area 10
Although this region is extensive in humans, its function is poorly understood. Koechlin & Hyafil have proposed that processing of 'cognitive branching' is the core function of the frontopolar cortex. Cognitive branching enables a previously running task to be maintained in a pending state for subsequent retrieval and execution upon completion of the ongoing one. Many of our complex behaviors and mental activities require simultaneous engagement of multiple tasks, and they suggest the anterior prefrontal cortex may perform a domain‐general function in these scheduling operations. However, other hypotheses have also been proffered, such as those by Burgess et al.
Brodmann area 46
area 46, or BA
, or BA46
46, is part of the frontal cortex
in the human brain. It is between BA10 and BA45.
BA46 is known as middle frontal area 46. In the human brain it occupies approximately the middle third of the middle frontal gyrus and the most rostral portion of the inferior frontal gyrus. Brodmann area 46 roughly corresponds with the dorsolateral
prefrontal cortex (DLPFC), although the borders of area 46 are based on cytoarchitecture rather than function. The DLPFC also Brain: Brodmann area 46
encompasses part of granular frontal area 9, directly adjacent on the dorsal surface of the cortex.
Cytoarchitecturally, BA46 is bounded dorsally by the granular frontal area 9, rostroventrally by the frontopolar area 10 and caudally by the triangular area 45
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(Brodmann‐1909). There is some discrepancy between ) h
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the extent of BA8 (Brodmann‐1905) and the same area as described by Walker (1940)
The DLPFC plays a role in sustaining attention and working memory. Lesions to the DLPFC impair short‐term memory and cause difficulty inhibiting responses. Lesions may also eliminate much of the ability to make ability to make judgements
judgements about what's relevant and what's not as well as causing problems in organization
and what's not as well as causing problems in organization.
The DLPFC has recently been found to be involved in exhibiting self‐‐control
self
control. The dorsolateral prefrontal cortex, which is one of the few Brodmann area 11, or BA11, is part of the frontal cortex in the human brain. BA11 covers the medial part of the ventral surface of the frontal lobe.
Prefrontal area 11 of Brodmann‐1909 is a subdivision of the frontal lobe in the human defined on the basis of cytoarchitecture. Defined and illustrated in Brodmann‐1909, it included the areas subsequently illustrated in Brodmann‐10 as prefrontal area 11 and rostral area 12.
prefrontal area 11 is a subdivision of the cytoarchitecturally defined frontal region of cerebral cortex of the human. As illustrated in Brodmann‐10, It constitutes most of the orbital gyri, gyrus rectus
and the most rostral portion of the superior frontal gyrus. It is bounded medially by the inferior rostral sulcus (H) and laterally approximately by the frontomarginal sulcus (H). Cytoarchitecturally
it is bounded on the rostral and lateral aspects of the hemisphere by the frontopolar area 10, the orbital area 47, and the triangular area 45; on the medial surface it is bounded dorsally by the rostral area 12 and caudally by the subgenual area 25. In an earlier map, the area labeled 11, i.e., prefrontal area 11 of Brodmann‐1909, was larger; it included the area now designated rostral area 12.
The Brodmann
The Brodmann area 32
area 32, also known in the human brain as the dorsal anterior cingulate area 32, refers to a subdivision of the cytoarchitecturally
defined cingulate region of cerebral cortex. In the human it forms an outer arc around the anterior cingulate gyrus. The cingulate sulcus defines approximately its inner boundary and the superior rostral sulcus (H) its ventral boundary; rostrally it extends almost to the margin of the frontal lobe. Cytoarchitecturally it is bounded internally by the ventral anterior cingulate area 24, externally by medial margins of the agranular frontal area 6, intermediate frontal area 8, granular frontal area 9, frontopolar area 10, and prefrontal area 11‐1909. (Brodmann19‐09).
Dorsal region of anterior cingulate gyrus is associated with rational thought processes
rational thought processes, most notably active during the Stroop
Stroop task
task.
Brain: Brodmann area 11
Brain: Brodmann area 32
areas deactivated during REM sleep. Neuroscientist J. Allan Hobson has hypothesized that activation of the dorsolateral prefrontal cortex produce lucid dreams.
Stroop effect is a demonstration of the reaction time of a task. When the name of a color (e.g., "blue," "green," or "red") is printed in a color not denoted by the name (e.g., the word "red" printed in blue ink instead of red ink), naming the color of the word takes longer and is more prone to errors than when the color of the ink matches the name of the color. The effect is named after John Ridley Stroop who first published the effect in English in 1935. The effect had previously been published in Germany in 1929. The original paper has been one of the most cited papers in the history of experimental psychology, leading to more than 700 replications. The effect has been used to create a psychological test (Stroop
Stroop Test) that is widely used in Test
clinical practice and investigation.
This test is considered to measure selective attention, cognitive flexibility and processing speed, and it is used as a tool in the evaluation of executive functions. An increased interference effect is found in disorders such as brain damage, dementias
and other neurodegenerative diseases, attention‐deficit hyperactivity disorder, or a variety of mental disorders such as schizophrenia, addictions, and depression
The anterior cingulate cortex has been related to the processing of the Stroop
Stroop effect
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Brodmann area 24 area 24 is part of the anterior cingulate in the human brain.
In the human this area is known as ventral anterior cingulate area 24, and it refers to a subdivision of the cytoarchitecturally defined cingulate cortex region of cerebral cortex (area cingularis anterior ventralis). It occupies most of the anterior cingulate gyrus in an arc around the genu of corpus callosum. Its outer border corresponds approximately to the cingulate sulcus. Cytoarchitecturally it is bounded internally by the pregenual area 33, externally by the dorsal anterior area 33 externally by the dorsal anterior
cingulate area 32, and caudally by the ventral posterior cingulate area 23 and the dorsal posterior cingulate area 31.
Francis Crick, one of the discoverers of DNA, listed area 24 as the seat of free will because of its centrality in abulia
abulia and amotivational syndromes.
Brain: Brodmann area 24
Figure 1 from Experiment 2 of the original description of the Stroop
Effect (1935). 1 is the time that it takes to name the color of the dots while 2 is the time that it takes to say the color when there is a conflict with the written word
Aboulia or or Abulia
Abulia (from the Greek "αβουλία", meaning "non‐will"), in neurology, refers to a lack of will or initiative and is one of the Disorders of Diminished Motivation or DDM. Aboulia falls in the middle of the spectrum of diminished motivation, with apathy being less extreme and akinetic mutism being more extreme than aboulia. A patient with aboulia is unable to act or make decisions i d
independently. It may range in severity from subtle to d l I
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overwhelming. It is also known as Blocq's disease (which also refers to abasia and astasia‐abasia). Abulia was originally considered to be a disorder of the will.[
Amotivational syndrome is a psychological condition associated with diminished inspiration to participate in social situations and activities, with lapses in apathy caused by an external event, situation, substance (or lack of), relationship, or other cause.
While some have claimed that chronic use of cannabis causes amotivational
syndrome in some users, empirical studies suggest that there is no such thing as "amotivational syndrome", per se, but that chronic cannabis intoxication can lead to apathy and amotivation. From a World Health Organization report:
The evidence for an "amotivational syndrome" among adults consists largely of case histories and observational reports (e.g. Kolansky
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(
K l k and Moore, 1971; dM
1971
Millman and Sbriglio, 1986). The small number of controlled field and laboratory studies have not found compelling evidence for such a syndrome (Dornbush, 1974; Negrete, 1983; Hollister, 1986)... (I)t is doubtful that cannabis use produces a well defined amotivational syndrome. It may be more parsimonious to regard the symptoms of impaired motivation as symptoms of chronic cannabis intoxication rather than inventing a new psychiatric syndrome.
Aboulia has been known to clinicians since 1838. However, in the time since its inception, the definition of aboulia has been subjected to many different forms, some even contradictory with previous ones. Aboulia has been described as a loss of drive, expression, loss of behavior and speech output, slowing and prolonged speech latency, and reduction of spontaneous thought content and initiative. The clinical features most commonly associated with aboulia are:
1. Difficulty in initiating and sustaining purposeful movements 2. Lack of spontaneous movement 3. Reduced spontaneous movement 4. Increased response‐time to queries 5. Passivity Passivity
6. Reduced emotional responsiveness and spontaneity 7. Reduced social interactions 8. Reduced interest in usual pastimes
Especially in patients with progressive dementia, it may affect feeding. Patients may continue to chew or hold food in their mouths for hours without swallowing it. The behavior may be most evident after these patients have eaten part of their meals and no longer have strong appetites.
Apathy (also called impassivity or perfunctoriness) is a state of indifference, or the suppression of emotions such as concern, excitement, motivation and passion. An apathetic individual has an absence of interest in or concern about emotional, social, spiritual, philosophical or physical life.
They may lack a sense of purpose or meaning in their life. He or she may also exhibit insensibility or sluggishness. The hb
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opposite of apathy is flow. In positive psychology, apathy is described as a result of the individual feeling they have much more than the level of skill required to confront a challenge. It may also be a result of perceiving no challenge at all (e.g. the challenge is irrelevant to them, or conversely, they have learned helplessness).
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Brodmann area 25
area 25 (BA
(BA25
25) ) is an area in the cerebral cortex of the brain and delineated based on its cytoarchitectonic characteristics, also called the subgenual area, area subgenualis or subgenual
cingulate. It is the 25th "Brodmann area" defined by Korbinian Brodmann (thus its name). BA25 is located in the cingulate region as a narrow band in the caudal portion of the subcallosal area adjacent to the paraterminal gyrus. The posterior parolfactory sulcus separates the paraterminal
gyrus from BA25. Rostrally it is bound by the prefrontal area g
y
11 of Brodmann. This region is extremely rich in serotonin transporters and is considered as a governor for a vast network involving areas like hypothalamus and brain stem, which influences changes in appetite and sleep; the amygdala and insula, which affect the mood and anxiety; the hippocampus, which plays an important role in memory formation; and some parts of the frontal cortex responsible Brain: Brodmann area 25
for self‐‐esteem
for self
esteem.
Brodmann area 33
area 33, also known as , also known as pregenual area 33
area 33, , is a subdivision of the cytoarchitecturally defined cingulate region of cerebral cortex. It is a narrow band located in the anterior cingulate gyrus adjacent to the supracallosal gyrus in the depth of the callosal sulcus. of the callosal
sulcus
Cytoarchitecturally it is bounded by the ventral anterior cingulate area 24 and the supracallosal gyrus
(Brodmann‐1909).
Brain: Brodmann area 33
One study has noted that BA25 is metabolically overactive in treatment‐
resistant depression and has found that chronic deep brain stimulation in the white matter adjacent to the area is a successful treatment for some patients. A different study found that metabolic hyperactivity in this area is associated with poor therapeutic response of persons with Major Depressive Disorder to cognitive‐behavioral therapy and venlafaxine
Blood supply
Branches of the middle cerebral artery provide most of the arterial blood supply for the primary motor cortex.
The medial aspect (leg areas) is supplied by branches of the anterior cerebral artery.
Neural input from the thalamus
The primary motor cortex receive thalamic input from the Ventral lateral nucleus of the Thalamus.
Pathology
Lesions of the precentral gyrus result in paralysis of the contralateral side of the body (facial palsy, arm‐/leg monoparesis, hemiparesis) ‐ see upper motor neuron.
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