Chapter 16
SENSORY, MOTOR, AND INTEGRATIVE SYSTEMS
I. INTRODUCTION
A. The components of the brain interact to receive sensory input, integrate and store the information,
and transmit motor responses.
B. To accomplish the primary functions of the nervous system there are neural pathways to transmit
impulses from receptors to the circuitry of the brain, which manipulates the circuitry to form
directives that are transmitted via neural pathways to effectors as a response.
II. SENSATION
A. Sensation is a conscious or unconscious awareness of external or internal stimuli. Perception is the
conscious awareness and interpretation of sensations.
B. Sensory receptors transmit four kinds of information: stimulus modality, location, intensity, and
duration.
1. Modality refers to the type of stimulus or sensation it produces (vision, taste, etc.).
2. Location is also indicated by which nerve fibers are firing. Sensory projection is the
ability of the brain to identify the site of stimulation.
3. Intensity can be encoded by firing frequencies of nerve fibers, recruitment of more
fibers, and stimulation of fibers that vary in their thresholds.
4. Duration is encoded in the way nerve fibers change their firing frequencies over time.
Phasic receptors tend to generate a burst of action potentials and then quickly adapt and
stop transmitting impulses. Tonic receptors adapt slowly and continue to transmit
impulses.
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C. Components of Sensation
1. For a sensation to arise, four events must occur.
2. These are stimulation, transduction, conduction, and translation.
a. A stimulus, or change in the environment, capable of initiating a nerve impulse by the
nervous system must be present.
b. A sensory receptor or sense organ must pick up the stimulus and transduce (convert)
it to a nerve impulse by way of a generator potential.
c. The impulse(s) must be conducted along a neural pathway from the receptor or sense
organ to the brain.
d. A region of the brain or spinal cord must translate the impulse into a sensation.
D. Sensory Receptors
1. Classification of Sensory Receptors
a. On a microscopic level, sensory receptors are free nerve endings, encapsulated nerve
endings at the dendrites of first-order sensory neurons, or separate cells that synapse
with first order sensory neurons.
1) When stimulated the dendrites of free nerve endings, encapsulate nerve
endings, and the receptive part of olfactory receptors produce generator
potentials.
2) The specialized cells that act as receptors for the special senses of vision,
hearing, equilibrium, and taste produce receptor potentials in response to
stimuli.
3) Generator and receptor potentials are graded, local potentials; generator
potentials trigger action potentials, whereas receptor potentials doe not.
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b. Senses are classified as to whether they are general or special.
1. General senses (also called somatic, somatosensory, or somesthetic) have
receptors that are widely distributed throughout the body. These detect touch,
pressure, heat, cold, and pain, as well as many other stimuli that we do not
consciously perceive
2. The special senses are limited to the head, including vision, hearing,
equilibrium, taste, and smell.
c. According to location, receptors are classified as exteroceptors, interoceptors
(visceroceptors), and proprioceptors.
d. On the basis of type of stimulus detected, receptors are classified as
mechanoreceptors, thermoreceptors, nociceptors, photoreceptors, and
chemoreceptors.
2.
Adaptation of Sensory Receptors
a. A characteristic of many sensations is adaptation, i.e., a change in sensitivity (usually a
decrease) to a long-lasting stimulus.
b. The receptors involved are important in signaling information regarding steady states
of the body.
phasic
tonic
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III. SOMATIC SENSATIONS
A. Tactile Sensations
1. Tactile sensations are touch, pressure, and vibration plus itch and tickle.
2. Tactile receptors include corpuscles of touch, hair root plexuses, type I and type II cutaneous
mechanoreceptors, lamellated corpuscles, and free nerve endings.
3. Touch
a. Crude touch refers to the ability to perceive that something has simply touched the
skin; discriminative touch refers to the ability to recognize exactly what point of the
body is touched.
b. Receptors for touch include corpuscles of touch (Meissner’s corpuscles) and hair root
plexuses; these are rapidly adapting receptors.
c. Type I cutaneous mechanoreceptors (tactile or Merkel discs) and type II cutaneous
mechanoreceptors (end organs of Ruffini) are slowly adapting receptors for touch.
4. Pressure and Vibration
a. Pressure sensations generally result from stimulation of tactile receptors in deeper
tissues and are longer lasting and have less variation in intensity than touch
sensations; pressure is a sustained sensation that is felt over a larger area than touch.
1) Receptors for pressure are type II cutaneous mechanoreceptors and
lamellated (Pacinian) corpuscles.
2) Like corpuscles of touch, lamellated corpuscles adapt rapidly.
b. Vibration sensations result from rapidly repetitive sensory signals from tactile
receptors; the receptors for vibration sensations are corpuscles of touch and
lamellated corpuscles, which detect low-frequency and high-frequency vibrations,
respectively.
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5. Itch and Tickle
a. Itch and tickle receptors are free nerve endings.
b. Tickle is the only sensation that you may not elicit on yourself.
B. Thermal Sensations
1. Free nerve endings with 1mm diameter receptive fields on the skin surface.
a. Cold receptors in the stratum basale respond to temperatures between 50-105 degrees F.
b. Warm receptors in the dermis respond to temperatures between 90-118 degrees F.
2. Both adapt rapidly at first, but continue to generate impulses at a low frequency.
3. Pain is produced below 50 and over 118 degrees F.
C. Pain Sensations
1. Pain receptors (nociceptors) are free endings that are located in nearly every body tissue
a. Free nerve endings found in every tissue of body except the brain
b. adaptation is slight if it occurs at all.
2. Stimulated by excessive distension, muscle spasm, & inadequate blood flow
3. Tissue injury releases chemicals such as K+, kinins or prostaglandins that stimulate
nociceptors
4. Types of Pain
a. Fast pain (acute)
1. occurs rapidly after stimuli (.1 second)
2. sharp pain like needle puncture or cut
3. not felt in deeper tissues
4. larger A nerve fibers
b. Slow pain (chronic)
1. begins more slowly & increases in intensity
2. aching or throbbing pain of toothache
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3. in both superficial and deeper tissues
4. smaller C nerve fibers
5. Types of Pain
a. Somatic pain that arises from the stimulation of receptors in the skin is superficial,
while somatic pain that arises from skeletal muscle, joints, and tendons is deep.
b. Visceral pain, unlike somatic pain, is usually felt in or just under the skin that overlies
the stimulated organ
1.localized damage (cutting) intestines may cause no pain, but diffuse visceral
stimulation can be severe
a. distension of a bile duct from a gallstone
b. distension of the ureter from a kidney stone
2. pain may also be felt in a surface area far from the stimulated organ in a
phenomenon known as referred pain.
3. Referred Pain
a.Visceral pain that is felt just deep to the skin overlying the stimulated organ
or in a surface area far from the organ.
b. Skin area & organ are served by the same segment of the spinal cord.
1. Heart attack is felt in skin along left arm since both are supplied by
spinal cord segment T1-T5
•
Pain is also classified according to its point of origin.
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Somatic pain arises from the skin, muscles, and joints, and can be superficial or
deep.
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Visceral pain is less localized due to fewer nociceptors in the viscera, and is
commonly caused by stretch, chemicals, or ischemia.
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•
Damaged tissues release a number of chemicals that stimulate nociceptors, with bradykinin
as one of the most potent stimulators.
•
Nociceptors are found in nearly all organs, except the brain, and are especially numerous
in the skin and mucous membranes. Two types of nociceptors correspond to different pain
sensations.
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Fast (acute) pain, the sharp, stabbing feeling perceived at the time of injury, is
carried on myelinated pain fibers.
•
Slow (chronic) pain is carried on unmyelinated pain fibers, for a sensation of
diffuse, dull ache.
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Pain signals traveling on first-order neurons travel to an interneuron hooked up to the
spinothalamic tract, then to the thalamus, which relays the signal to the cerebral cortex.
Substance P is the excitatory neurotransmitter for this pathway.
•
Pain signals also travel up the spinoreticular tract to the reticular formation where the
state of arousal may be affected.
•
Referred pain occurs when pain fibers from deep tissues merge with those of the skin, and
follow the same pathway to the thalamus. Knowledge of the origins of referred pain can be
a useful diagnostic tool.
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The CNS has analgesic mechanisms that help alleviate the pain of childbirth, for example.
•
Oligopeptides with analgesic qualities are the enkephalins, endorphins, and
dynorphins (collectively, the endogenous opioids).
•
The endogenous opiates act as neuromodulators to block the transmission of pain
and produce feelings of pleasure.
•
The reticular formation may also moderate sensitivity to pain by means of
endorphins.
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•
Some interneurons of the dorsal horn inhibit second-order neurons of the pain
pathway, especially after receiving input from touch fibers.
4. Pain Relief
a. Multiple sites of analgesic action:
1. Aspirin and ibuprofen block formation of prostaglandins that stimulate
nociceptors.
2. Novocaine blocks conduction of nerve impulses along pain fibers by inhibiting
sodium voltage gates.
3. Morphine lessen the perception of pain in the brain by mimicking the effects of
the bodies neuropeptides.
D. Proprioceptive Sensations
1. Receptors located in skeletal muscles, in tendons, in and around joints, and in the internal ear
convey nerve impulses related to muscle tone, movement of body parts, and body position.
This awareness of the activities of muscles, tendons, and joints and of balance or equilibrium
is provided by the proprioceptive or kinesthetic sense.
2. 2. Proprioceptive or Kinesthetic Sense
a. Awareness of body position & movement
1. walk or type without looking
2. estimate weight of objects
b. Proprioceptors adapt only slightly
c. Sensory information is sent to cerebellum & cerebral cortex
1. signals project from muscle, tendon, joint capsules & hair cells in the vestibular
apparatus
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2. receptors discussed here include muscle spindles, tendon organs (Golgi tendon
organs), and joint kinesthetic receptors.
3. Muscle Spindles
a. Specialized intrafusal muscle fibers enclosed in a CT capsule and innervated by gamma
motor neurons
b. Stretching of the muscle stretches the muscle spindles sending sensory information back to
the CNS
c. Spindle sensory fiber monitor changes in muscle length
d. Brain regulates muscle tone by controlling gamma fibers
4. Golgi Tendon Organs
a. Found at junction of tendon & muscle
b. Consists of an encapsulated bundle of collagen fibers laced with sensory fibers
c. When the tendon is overly stretched, sensory signals head for the CNS & resulting in the
muscle’s relaxation
5. Joint Receptors
a. Ruffini corpuscles
1. found in joint capsule
2. respond to pressure
b. Pacinian corpuscles
1. found in connective tissue around the joint
2. respond to acceleration & deceleration of joints
6. Chemoreceptors – Respond to chemicals in solution such as H+, CO2, and O2.
Receptor:
Examples:
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7. Baroreceptors – Respond to the stretching of the wall of an organ.
Receptor:
Examples:
IV. SOMATIC SENSORY PATHWAYS
A. Somatic sensory pathways relay information from somatic receptors to the primary somatosensory
area in the cerebral cortex.
1. The pathways consist of first-order, second-order, and third-order neurons.
2. Axon collaterals of somatic sensory neurons simultaneously carry signals into the cerebellum
and the reticular formation of the brain stem.
B. Posterior Column-Medial Lemniscus Pathway to the Cortex
1. The nerve impulses for conscious proprioception and most tactile sensations ascend to the
cortex along a common pathway formed by three-neuron sets.
2. Impulses conducted along this pathway are concerned with discriminative touch,
stereognosis, proprioception, weight discrimination, and vibratory sensations.
C. Anterolateral Pathways to the Cortex
1. The anterolateral or spinothalamic pathways carry mainly pain and temperature impulses.
2. They also relay the sensations of tickle and itch and some tactile impulses.
D. Somatosensory Cortex
1. The neural pathway for tickle, itch, crude touch, and pressure is the anterior spinothalamic
pathway.
2. The relative sizes of the areas in the somatosensory cortex are proportional to the number of
specialized sensory receptors within a part of the body.
E. Somatic Sensory Pathways to the Cerebellum
1. The posterior spinocerebellar and the anterior spinocerebellar tracts are the major routes
whereby proprioceptive impulses reach the cerebellum.
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2. The cuneocerebellar and rostaral spinocerebellar tracts convey impulses from
proprioceptors of the trunk and upper limbs.
F. Spinal Tracts
1.Ascending tracts carry sensory information up the spinal cord; descending tracts carry motor
information down it. Many fibers exhibit decussation. Ascending tracts typically involve a
three neuron pathway made up of a first order neuron, second order neuron, and a third
order neuron (see diagram). The major ascending tracts are:
a.Dorsal (posterior) column.
1.Fasciculi cuneatus
2.Fasciculi gracilis
3.Functions. Fine touch, conscious proprioception, and vibratory sensations.
b.Anterior and lateral spinothalamic.
1.Functions. Carries impulses for (LS) pain, thermal sensations, (AS) itch, tickle
pressure, vibrations and crude touch.
c.Anterior and posterior spinocerebellar.
1.Functions. Convey nerve impulses from proprioceptors in the trunk and lower limbs
to the cerebellum.
G. Tertiary syphilis causes a progressive degeneration of the posterior portions of the spinal cord
resulting in lost somatic sensations and proprioception failure.
Spinal Tracts
Ascending tracts carry sensory information up the spinal cord; descending tracts carry motor information down
it. Many fibers exhibit decussation. Ascending tracts typically involve a three neuron pathway made up of a
first order neuron, second order neuron, and a third order neuron (see diagram). The major ascending
tracts are:
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Dorsal (posterior) column.
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•
•
Fasciculi cuneatus
•
Fasciculi gracilis
•
Functions. Fine touch, conscious proprioception, and vibratory sensations.
Anterior and lateral spinothalamic.
•
Functions. Carries impulses for (LS) pain, thermal sensations, (AS) itch, tickle
pressure, vibrations and crude touch.
•
Anterior and posterior spinocerebellar.
•
Functions. Convey nerve impulses from proprioceptors in the trunk and lower
limbs to the cerebellum.
V. SOMATIC MOTOR PATHWAYS
A. The motor cortex (primary motor area or precentral gyrus) is the major control region for initiation
of voluntary movements. The adjacent premotor area and even the somatosensory cortex also
contribute fibers to the descending motor pathways.
1. Different muscles are not represented equally in the motor cortex.
2. The degree of representation is proportional to the number of motor units in a particular
muscle of the body.
B. Voluntary motor impulses are propagated from the motor cortex to somatic efferent neurons
(voluntary motor neurons) that innervate skeletal muscles via the direct or pyramidal pathways. The
simplest pathways consist of upper and lower motor neurons.
1. The direct pathways include the lateral and anterior corticospinal tracts and
corticobulbar tracts.
2. The various tracts of the pyramidal system convey impulses from the cerebral cortex that
result in precise muscular movements.
3. The lateral corticospinal, anterior corticospinal, and corticobulbar tracts contain axons
of upper motor neurons.
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4. Damage or disease of lower motor neurons produces flaccid paralysis of muscles on the
same side of the body. Injury or disease of upper motor neurons results in spastic
paralysis of muscles on the opposite side of the body.
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Motor tracts typically involve two neuron pathways made up of a upper motor neuron and
a lower motor neuron. The major motor tracts are:
•
Direct or Pyramidal Pathways.
•
Lateral corticospinal.
•
•
Ventral (anterior) corticospinal.
•
•
Functions. Voluntary movements of the limbs, hand, and feet.
Functions. Voluntary movements of the axial skeleton movement.
Corticobulbar.
•
Functions. Voluntary movements of the head and neck.
C. Indirect Pathways
1. Indirect or extrapyramidal pathways include all somatic motor tracts other than the
corticospinal and corticobulbar tracts.
a. Indirect pathways involve the motor cortex, basal ganglia, thalamus, cerebellum,
reticular formation, and nuclei in the brain stem.
b. Major indirect tracts are the rubriospinal, tectospinal, vestibulospinal, and
reticulospinal tracts.
•
Motor tracts typically involve two neuron pathways made up of a upper motor neuron and a
lower motor neuron. The major motor tracts are:
•
Indirect or Extrapyramidal Pathways.
•
Tectospinal.
•
Functions. Reflexive head-turning in response to visual and auditory
stimuli.
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•
Lateral and medial reticulospinal.
•
•
Functions. Balance and posture, regulation of awareness of pain.
Vestibulospinal.
•
Functions. Balance and posture.
D. Basal Ganglia
1. The circuit from the cerebral cortex to basal ganglia to thalamus to cortex seems to function in
initiating and terminating movement.
a. basal ganglia also suppress unwanted movements
b. basal ganglia may influence aspects of cortical function including sensory, limbic,
cognitive, and linguistic functions.
c. Damage to the basal ganglia results in uncontrollable, abnormal body movements,
often accompanied by muscle rigidity and tremors.
Parkinson disease and Huntington disease result from damage to the basal ganglia.
F. Cerebellum
1. The cerebellum is active in both learning and performing rapid, coordinated, highly
skilled movements and in maintaining proper posture and equilibrium.
2. The four aspects of cerebellar function
a. monitoring intent for movement,
b. monitoring actual movement,
c. comparing intent with actual performance, and
d. sending out corrective signals
3. Damage to the cerebellum is evidenced by ataxia and intention tremors.
VI. INTEGRATIVE FUNCTIONS
A. The integrative functions include sleep and wakefulness, memory, and emotional responses.
B. Wakefulness and Sleep
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1. Reticular Activating System (RAS)
a. Sleep and wakefulness are integrative functions that are controlled by the
reticular activating system.
b. Arousal, or awakening from a sleep, involves increased activity of the RAS.
1) Once the RAS is activated, the cerebral cortex is also activated and arousal
occurs.
2) The result is a state of wakefulness called consciousness.
c. Damage to the RAS can produce coma, a state of deep unconsciousness from which
the person cannot be aroused.
2. Wakefulness and Sleep
a. Circadian rhythm
1. 24 hour cycle of sleep and awakening
2. established by hypothalamus
b. EEG recordings show large amount of activity in cerebral cortex when awake
c. During sleep, a state of altered consciousness or partial unconsciousness from which
an individual can be aroused by different stimuli,
d. During sleep activity in the RAS is very low.
e. Normal sleep consists of two types:
1. non-rapid eye movement sleep (NREM) and
2. rapid eye movement sleep (REM)
f. Triggers for sleep are unclear
1. adenosine levels increase with brain activity
2. adenosine levels inhibit activity in RAS
3. caffeine prevents adenosine from inhibiting RAS
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g. Non-rapid eye movement or slow wave sleep consists of four stages, each of which
gradually merges into the next.
1. Stage 1
- person is drifting off with eyes closed (first few minutes)
2. Stage 2
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fragments of dreams
–
eyes may roll from side to side
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Sleep spindles occur
3. Stage 3
–
very relaxed, moderately deep
–
20 minutes, body temperature & BP have dropped
–
Theta waves appear
4. Stage 4 = deep sleep
–
bed-wetting & sleep walking occur in this phase
–
Delta waves dominate
h. REM Sleep
1. Most dreams occur during REM sleep
2. In first 90 minutes of sleep:
–
go from stage 1 to 4 of NREM,
–
go up to stage 2 of NREM
–
to REM sleep
3. Cycles repeat until total REM sleep totals 90 to 120 minutes
4. Neuronal activity & oxygen use is highest in REM sleep
5. Total sleeping & dreaming time decreases with age
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6. Several times per night, the sleeper "backtracks" to stage 1 and enters rapid
eye movement (REM) sleep. It is also called paradoxical sleep because of the
difficulty with which a sleeper can be aroused. Most dreams occur during this
period. As sleep continues, periods of REM sleep get longer
i. Regulation of Sleep
•
Different parts of the brain mediate NREM and REM sleep. Neurons in the preoptic area
of the hypothalamus, the basal forebrain, and the medulla govern NREM sleep, whereas
neurons in the pons and midbrain turn REM sleep on and off. Substances that affect
these areas include adenosine, which accumulates during periods of high ATP use by the
nervous system. Adenosine binds to specific receptors, called A1 receptors, and inhibits
certain cholinergic neurons of the Reticular System that participate in arousal. Thus,
activity in the RAS during sleep is low due to inhibitory effects of adenosine. Caffeine
and theophylline bind to and block A1 receptors, preventing adenosine bonding and
inducing sleep.
2. Sleep
a. During sleep, a state of altered consciousness or partial unconsciousness from which
an individual can be aroused by different stimuli, activity in the RAS is very low.
b. Normal sleep consists of two types: non-rapid eye movement sleep (NREM) and rapid
eye movement sleep (REM).
1) Non-rapid eye movement or slow wave sleep consists of four stages, each
of which gradually merges into the next. Each stage has been identified by
EEG recordings.
2) Most dreaming occurs during rapid eye movement sleep.
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Sleep
•
Sleep is a temporary state of unconsciousness from which the person can be aroused, whereas a
coma is a state of unconsciousness from which the person cannot be aroused.
•
The biological clock that regulates sleep-wake cycles is the suprachiasmatic nucleus of the
hypothalamus. The hypothalamus and brainstem control sleep.
•
We pass through four stages of brain activity after falling asleep. These four stages belong to
NREM sleep.
•
Stage 1 sleep occurs after first falling asleep; alpha waves are dominant, and the person is
easily aroused.
•
•
Stage 2 sleep is characterized by brain waves called sleep spindles and an irregular EEG.
•
During stage 3, sleep deepens, vital signs decline, and theta waves appear.
•
Stage 4 (slow-wave sleep) is dominated by delta waves. The person is deeply asleep.
Several times per night, the sleeper "backtracks" to stage 1 and enters rapid eye movement
(REM) sleep. It is also called paradoxical sleep because of the difficulty with which a sleeper
can be aroused. Most dreams occur during this period. As sleep continues, periods of REM sleep
get longer.
•
Different parts of the brain mediate NREM and REM sleep. Neurons in the preoptic area of the
hypothalamus, the basal forebrain, and the medulla govern NREM sleep, whereas neurons in
the pons and midbrain turn REM sleep on and off. Substances that affect these areas include
adenosine, which accumulates during periods of high ATP use by the nervous system.
Adenosine binds to specific receptors, called A1 receptors, and inhibits certain cholinergic
neurons of the Reticular System that participate in arousal. Thus, activity in the RAS during
sleep is low due to inhibitory effects of adenosine. Caffeine and theophylline bind to and
block A1 receptors, preventing adenosine bonding and inducing sleep.
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C. Learning and Memory
1. Learning is the ability to acquire new knowledge or skills through instruction or
experience. Memory is the process by which that knowledge is retained over time.
a. For an experience to become part of memory, it must produce persistent
functional changes that represent the experience in the brain.
b. The capability for change with learning is called plasticity.
2. Memory is the ability to recall thought and is generally classified into two kinds based on
how long the memory persists: short-term and long-term memory.
a. A memory trace in the brain is called an engram (a change in the brain that
represents the experience).
b. Short-term memory lasts only seconds or hours and is the ability to recall bits of
information; it is related to electrical and chemical events.
c. Long-term memory lasts from days to years and is related to anatomical and
biochemical changes at synapses.
Memory
•
Terminology.
•
Learning. The ability to acquire new knowledge or skills through instruction or
experience.
•
Memory. The process by which knowledge is retained over time.
•
Engram (memory trace). The basis of memory is the memory trace (engram), a
pathway where new synapses have been formed or existing synapses have been modified.
•
•
Memory consolidation. Conversion of short-term memory to long-term memory.
Types of memory.
Short-term memory (working memory). The temporary ability to recall a few pieces of information
for seconds to minutes. thought to involve reverberating circuits.
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•
Long-term memory. Memory which lasts from days to years. Involves anatomical and
physiological changes in neurons such as increased production of neurotransmitters,
increased dendritic branching, and increased numbers of synaptic knobs.
•
Brain areas involved in memory.
•
Hippocampus. Involved in memory consolidation.
•
Amygdala. Association of memories and emotions.
•
Hypothalamus. Association of memories and emotions.
•
Prefrontal cortex. Retrieving memories.
 Amnesia
•
Amnesia refers to the loss of memory
•
Anterograde amnesia is the loss of memory for events that occur after the trauma; the inability to form
new memories.
•
Retrograde amnesia is the loss of memory for events that occurred before the trauma; the inability to
recall past events.

Factors affecting memory.
•
Emotional state.
•
Rehearsal.
•
Association of new information with old information.
•
Automatic memory.
VII. DISORDERS: HOMEOSTATIC IMBALANCES
A. Phantom pain is the sensations of pain in a limb that has been amputated; the brain interprets nerve
impulses arising in the remaining proximal portions of the sensory nerves as coming from the
nonexistent (phantom) limb. Another explanation is that the neurons in the brain that received input
from the missing limbs are still active.
B. Spinal Cord Injury
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1. Spinal cord injury can be due to damage in a number of ways, such as compression or
transection, and the location and extent of damage determines the type and degree of loss in
neural abilities.
–
tumor, herniated disc, clot, trauma …
2. Paralysis
a. monoplegia is paralysis of one limb only
b. diplegia is paralysis of both upper or both lower
c. hemiplegia is paralysis of one side
d. quadriplegia is paralysis of all four limbs
3. Spinal shock is loss of reflex function (areflexia)
a. slow heart rate, low blood pressure, bladder problem
b. reflexes gradually return
C. Cerebral Palsy
1. Cerebral palsy (CP) is a disorder that affects muscle tone, movement, and motor skills (the ability to
move in a coordinated and purposeful way). Cerebral palsy can also lead to other health issues, including vision,
hearing, and speech problems, and learning disabilities.
2. CP is usually caused by brain damage that occurs before or during a child's birth, or during the
first 3 to 5 years of a child's life. There is no cure for CP, but treatment, therapy, special equipment, and,
in some cases, surgery can help a child who is living with the condition.
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