The Human Brain
Master Watermark Image:
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
“If the human brain were so simple
that we could understand it, we
would be so simple that we
couldn’t”
-Emerson Pugh, The Biological Origin of Human
Values (1977)
Phineas Gage
•
•
•
•
•
September 13th, 1848
Phineas 25 years old
Rutland & Burlington Railroad, Cavendish, VT
Paving the way for new RR tracks
“Tamping Iron”
– 1.25in x 3ft
Phineas Gage
• Accident
– Quick Recovery
• Months later: “No longer Gage”
– Before: capable, efficient, best foreman, well-balanced mind
– After: extravagant, anti-social, liar, grossly profane
• Stint with P.T Barnum
• Died 12 years later
• Watch Clip
Further Investigation
Phineas Gage:
Phineas Gage was a railroad worker in the 19th century living in
Cavendish, Vermont. One of his jobs was to set off explosive charges in large rock in
order to break them into smaller pieces. On one of these instances, the detonation
occurred prior to his expectations, resulting in a 42 inch long, 1.2 inch wide, metal rod
to be blown right up through his skull and out the top. The rod entered his skull below
his left cheek bone and exited after passing through the anterior frontal lobe of his
brain.
Frontal
Remarkably, Gage never lost consciousness, or quickly regained it (there is still some
debate), suffered little to no pain, and was awake and alert when he reached a doctor
approximately 45 minutes later. He had a normal pulse and normal vision, and
following a short period of rest, returned to work several days later. However, he was
not unaffected by this accident.
http://www.sruweb.com/~walsh/gage5.jpg
Learn more about Phineas Gage: http://en.wikipedia.org/wiki/Phineas_Gage
Frontal
Q: Recalling what you have just learned regarding the frontal lobe, what
possible problems or abnormalities may Gage have presented with
subsequent to this type of injury (remember the precise location of the rod
through his brain)?
Q: It is suggested that Gage’s injury inspired the development of what at one
time was a widely used medical procedure. What might this procedure be, and
how does it relate to Gage’s injury?
Frontal
Evolution of the Brain
Reptilian  Paleomammalian  Neomammalian
The Brain
• Brainstem
– responsible for
automatic survival
functions
• Medulla
– controls heartbeat
and breathing
The Brain
• Pons
- Involved with breathing and circulatory
function
- Involved in sleeps and dreams
- Helps to maintain homeostasis
- Homeostasis: how the body self-regulates
Parts of the Brain
THALAMUS
 Relays
messages
amygdala
hippocampus
pituitary
CEREBELLUM
 Coordination
and balance
BRAINSTEM  Heart
rate and breathing
Reticular Formation
•Widespread connections
•Arousal of the brain as a
whole
•Reticular activating system
(RAS)
•Maintains consciousness
and alertness
•Functions in sleep and
arousal from sleep
The Cerebellum
– helps coordinate
voluntary
movement and
balance
The Limbic System
• Hypothalamus, pituitary,
amygdala, and hippocampus all
deal with basic drives, emotions,
and memory
• Hippocampus  Memory
processing
• Amygdala  Aggression (fight)
and fear (flight)
• Hypothalamus  Hunger, thirst,
body temperature, pleasure;
regulates pituitary gland
(hormones)
The Limbic System
 Hypothalamus
 neural structure lying below
(hypo) the thalamus; directs
several maintenance
activities
 eating
 drinking
 body temperature
 helps govern the endocrine
system via the pituitary
gland
 linked to emotion
 (show video)
The Limbic System
Show self stimulation clip
The Limbic System
• Amygdala
– two almond-shaped
neural clusters that
are components of
the limbic system
and are linked to
emotion and fear
August 1st, 1966
Charles Whitman
The Brain
• Thalamus
– the brain’s sensory
switchboard, located on
top of the brainstem
– it directs messages to
the sensory receiving
areas in the cortex and
transmits replies to the
cerebellum and medulla
The Cerebral Cortex
• Cerebral Cortex
– the body’s ultimate
control and
information
processing center
The lobes of the cerebral hemispheres
The lobes of the cerebral hemispheres
Planning, decision
making speech
Sensory
Auditory
Vision
The Cerebral Cortex
• Frontal Lobes
– involved in speaking and muscle
movements and in making plans
and judgments
– the “executive”
• Parietal Lobes
– include the sensory cortex
The Cerebral Cortex
• Occipital Lobes
– include the visual areas, which receive
visual information from the opposite
visual field
• Temporal Lobes
– include the auditory areas, each of
which receives auditory information
primarily from the opposite ear
The Cerebral Cortex
•
•
•
•
Frontal (Forehead to top)  Motor Cortex
Parietal (Top to rear)  Sensory Cortex
Occipital (Back)  Visual Cortex
Temporal (Above ears)  Auditory Cortex
Motor/Sensory Cortex
• Contralateral
• Homunculus
• Unequal
representation
Sensory Areas – Sensory Homunculus
Figure 13.10
The Cerebral Cortex
 Aphasia
 impairment of language, usually caused by left
hemisphere damage either to Broca’s area (impairing
speaking) or to Wernicke’s area (impairing
understanding) –see clips
 Broca’s Area
 an area of the left frontal lobe that directs the muscle
movements involved in speech
 Wernicke’s Area
 an area of the left temporal lobe involved in language
comprehension and expression
Language Areas
• Broca 
Expression
• Wernicke 
Comprehensionan
and reception
• Aphasias
LEFT HEMISPHERE
Paul Broca [1800s]
• Suggested localization
Techniques to examine functions
of the brain
1. Remove part of
the brain & see
what effect it has
on behavior
2. Examine humans
who have suffered
brain damage
3. Stimulate the
brain
4. Record brain
activity
Brain Lateralization
Our Divided Brains
• Corpus collosum –
large bundle of
neural fibers
(myelinated axons,
or white matter)
connecting the two
hemispheres
Hemispheric Specialization
LEFT
Symbolic thinking
(Language)
Detail
Literal meaning
RIGHT
Spatial perception
Overall picture
Context, metaphor
Contra-lateral division
of labor
• Right hemisphere
controls left side of body
and visual field
• Left hemisphere controls
right side of body and
visual field
Part I:
Lobes, the Cerebral Cortex, and Cortical Regions of the Brain
Objectives:
• Students will be able to describe the general structure of the
Cerebrum and Cerebral Cortex.
• Students will be able to identify the Cerebrum, the Lobes of
the Brain, the Cerebral Cortex, and its major regions/divisions.
• Students will be able to describe the primary functions of
the Lobes and the Cortical Regions of the Brain.
Cerebrum -The largest division of the brain.
It is
divided into two hemispheres, each of which is
divided into four lobes.
Cerebrum
Cerebrum
Cerebellum
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
Cerebral Cortex - The outermost layer of gray
matter making up the superficial aspect of the
cerebrum.
Cerebral Cortex
Cerebral
Cortex
http://www.bioon.com/book/biology/whole/image/1/1-6.tif.jpg
Cerebral Features:
• Gyri – Elevated ridges “winding” around the brain.
• Sulci – Small grooves dividing the gyri
– Central Sulcus – Divides the Frontal Lobe from the Parietal
Lobe
• Fissures – Deep grooves, generally dividing large
regions/lobes of the brain
– Longitudinal Fissure – Divides the two Cerebral Hemispheres
– Transverse Fissure – Separates the Cerebrum from the
Cerebellum
– Sylvian/Lateral Fissure – Divides the Temporal Lobe from the
Frontal and Parietal Lobes
Gyri (ridge)
Sulci
(groove)
Fissure
(deep groove)
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
Specific Sulci/Fissures:
Central Sulcus
Longitudinal Fissure
Sylvian/Lateral
Fissure
Transverse Fissure
http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
http://www.dalbsoutss.eq.edu.au/Sheepbrains_Me/human_brain.gif
Lobes of the Brain (4)
•
•
•
•
Frontal
Parietal
Occipital
Temporal
http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
* Note: Occasionally, the Insula is considered the fifth lobe. It is located deep
to the Temporal Lobe.
Lobes of the Brain - Frontal
• The Frontal Lobe of the brain is located deep to the
Frontal Bone of the skull.
• It plays an integral role in the following functions/actions:
- Memory Formation
- Emotions
- Decision Making/Reasoning
- Personality
(Investigation: Phineas
Investigation
(PhineasGage)
Gage)
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Frontal Lobe - Cortical Regions
• Primary Motor Cortex (Precentral Gyrus) – Cortical site
involved with controlling movements of the body.
• Broca’s Area – Controls facial neurons, speech, and language
comprehension. Located on Left Frontal Lobe.
– Broca’s Aphasia – Results in the ability to comprehend speech, but
the decreased motor ability (or inability) to speak and form words.
• Orbitofrontal Cortex – Site of Frontal Lobotomies
* Desired Effects:
- Diminished Rage
- Decreased Aggression
- Poor Emotional
Responses
* Possible Side Effects:
- Epilepsy
- Poor Emotional Responses
- Perseveration (Uncontrolled, repetitive
actions, gestures, or words)
• Olfactory Bulb - Cranial Nerve I, Responsible for sensation of Smell
Investigation (Phineas Gage)
Primary Motor
Cortex/ Precentral
Gyrus
Broca’s Area
Orbitofrontal
Cortex
Olfactory Bulb
Regions
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Lobes of the Brain - Parietal Lobe
• The Parietal Lobe of the brain is located deep to the
Parietal Bone of the skull.
• It plays a major role in the following functions/actions:
- Senses and integrates sensation(s)
- Spatial awareness and perception
(Proprioception - Awareness of
body/ body parts in space and
in relation to each other)
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Parietal Lobe - Cortical Regions
• Primary Somatosensory Cortex (Postcentral
Gyrus) – Site involved with processing of tactile
and proprioceptive information.
• Somatosensory Association Cortex - Assists
with the integration and interpretation of
sensations relative to body position and orientation
in space. May assist with visuo-motor coordination.
• Primary Gustatory Cortex – Primary site
involved with the interpretation of the sensation of
Taste.
Primary
Somatosensory
Cortex/
Postcentral Gyrus
Somatosensory
Association Cortex
Primary
Gustatory Cortex
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Regions
Lobes of the Brain – Occipital Lobe
• The Occipital Lobe of the
Brain is located deep to the
Occipital Bone of the Skull.
• Its primary function is the
processing, integration,
interpretation, etc. of VISION and
visual stimuli.
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Occipital Lobe – Cortical Regions
• Primary Visual Cortex – This is the primary
area of the brain responsible for sight recognition of size, color, light, motion,
dimensions, etc.
• Visual Association Area – Interprets
information acquired through the primary visual
cortex.
Primary Visual
Cortex
Visual
Association Area
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Regions
Lobes of the Brain – Temporal Lobe
• The Temporal Lobes are located on the sides of the
brain, deep to the Temporal Bones of the skull.
• They
play an integral role
in the following functions:
- Hearing
- Organization/Comprehension
of language
- Information Retrieval
(Memory and Memory Formation)
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Temporal Lobe – Cortical Regions
• Primary Auditory Cortex – Responsible for hearing
• Primary Olfactory Cortex – Interprets the sense of
smell once it reaches the cortex via the olfactory
bulbs. (Not visible on the superficial cortex)
• Wernicke’s Area – Language comprehension.
Located on the Left Temporal Lobe.
- Wernicke’s Aphasia – Language comprehension is
inhibited. Words and sentences are not clearly understood,
and sentence formation may be inhibited or non-sensical.
Primary
Auditory Cortex
Wernike’s Area
Primary Olfactory
Cortex (Deep)
Conducted from Olfactory Bulb
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Regions
• Arcuate Fasciculus - A white matter tract that connects Broca’s Area and
Wernicke’s Area through the Temporal, Parietal and Frontal Lobes. Allows
for coordinated, comprehensible speech. Damage may result in:
- Conduction Aphasia - Where auditory comprehension and speech
articulation are preserved, but people find it difficult to repeat heard
speech.
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Click the Region to see its Name
Korbinian Broadmann - Learn about the man who divided the Cerebral Cortex into 52 distinct regions:
http://en.wikipedia.org/wiki/Korbinian_Brodmann
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
B.
Lobes and Structures of the Brain
A.
G.
F.
C.
E.
D.
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
Lobes and Structures of the Brain
A. Central Sulcus
B. Frontal Lobe
C. Sylvian/Lateral Fissure
D. Temporal Lobe
A. (groove)
G.
B.
F.
E. Transverse Fissure
F. Occipital Lobe
G. Parietal Lobe
C. (groove)
D.
E.
(groove)
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
K.
A.
Cortical Regions
J.
I.
B.
H.
G.
C.
D.
E.
F.
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
A. Primary Motor Cortex/ Precentral Gyrus
B. Broca’s Area
C. Orbitofrontal Cortex
Cortical Regions
D. Primary Olfactory Cortex (Deep)
E. Primary Auditory Cortex
A.
F. Wernike’s Area
K.
I.
G. Primary Visual Cortex
B.
H. Visual
Association Area
H.
G.
I. Primary Gustatory Cortex
J. Somatosensory
Association Cortex
K. Primary Somatosensory
Cortex/ Postcentral Gyrus
J.
C.
D.
E.
F.
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
Copyright: Gary Larson
Q: Assuming this comical situation was factually
accurate, what Cortical Region of the brain would
these doctors be stimulating?
A: Primary Motor Cortex
* This graphic representation of the regions of the Primary Motor Cortex and
Primary Sensory Cortex is one example of a HOMUNCULUS:
Homunculus
* Note: Homunculus literally means “little person,” and may refer to one whose body shape is
governed by the cortical area devoted to that body region.
Q: What do you notice about the proportions
depicted in the aforementioned homunculus?
A:
Q: What is meant by depicting these body parts
in such outrageous proportions?
Back-Hom.
Resources
Images:
•
•
•
•
•
•
http://www.dalbsoutss.eq.edu.au/Sheepbrains_Me/human_brain.gif
http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
http://www.bioon.com/book/biology/whole/image/1/1-6.tif.jpg
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
http://www.math.tu-dresden.de/~belov/brain/motorcor2.gif
Larson, Gary. The Far Side.
Phineas Gage:
•
•
•
•
http://www.sruweb.com/~walsh/gage5.jpg
http://soma.npa.uiuc.edu/courses/bio303/Image7.jpg
http://en.wikipedia.org/wiki/Phineas_Gage
http://scienceeducation.nih.gov/nihHTML/ose/snapshots/multimedia/ritn/Gage/Broken_brain1.html
Split Brain Patients
• Epileptic patients had corpus callosum cut to
reduce seizures in the brain
• Lives largely unaffected, seizures reduced
• Affected abilities related to naming objects in
the left visual field
Brain Plasticity
Brain Plasticity
• The ability of the brain to
reorganize neural pathways based
on new experiences
• Persistent functional changes in the
brain represent new knowledge
• Age dependent component
• Brain injuries
Environmental influences on
neuroplasticity
Impoverished environment
Enriched environment
Sensation
• The process by which the central nervous
system receives input from the
environment via sensory neurons
• Bottom up processing
Perception
• The process by which the brain interprets
and organizes sensory information
• Top-down processing
The psychophysics of sensation
• Absolute threshold  the minimum stimulation
needed to detect a stimulus with 50% accuracy
• Subliminal stimulation  below the absolute
threshold for conscious awareness
– May affect behavior without conscious
awareness
• Sensory adaptation/habituation  diminished
sensitivity to an unchanging stimulus
The five major senses
• Vision – electromagnetic
– Occipital lobe
• Hearing – mechanical
– Temporal lobe
• Touch – mechanical
– Sensory cortex
• Taste – chemical
– Gustatory insular cortex
• Smell – chemical
– Olfactory bulb
– Orbitofrontal cortex
– Vomeronasal organ?
The sixth sense
And the seventh…and eighth…and ninth…
• Vestibular  balance and motion
– Inner ear
• Proprioceptive  relative position of body parts
– Parietal lobe
• Temperature  heat
– Thermoreceptors throughout the body, sensory cortex
• Nociception  pain
– Nociceptors throughout the body, sensory cortex
Thresholds of the five major senses
The Retina
The retina at the
back of the eye is
actually part of
the brain!
Rods – brightness
Cones – color
Types of Neuroimaging
• Structural
– Magnetic resonance imaging
– Computed tomography
– Ultrasound
• Functional
– Functional MRI
– Positron emission tomography
– Single photon emission computed tomography
Magnetic Resonance Imaging
• Excellent for clearly visualizing structures in
soft tissues, such as the brain.
• Very commonly used in:
– Diagnosis
– Image-guided surgery and therapy
• By adjusting scanning settings, specific
features can be detected.
• MRI images are 2D slices through the body at
a specific location.
MRI Scanner
http://psyphz.psych.wisc.edu/
MRI Image Formation
• When the RF pulse is turned off, the hydrogen
protons return to their natural alignment within
the magnetic field.
• Energy is released.
• The coil detects this signal and sends it to a
computer for processing.
• The signal consists of complex values which
have real and imaginary components.
MRI Image Formation
Magnitude information from
signal
Phase information from signal
Fourier
Transfor
m
MRI Visualization
• A series of 2D MRI
images can be
combined together
to form a 3D
volume.
• This volume can
then be used to
generate realistic
visualizations and
models.
Computed Tomography (CT)
• Tomography
– Imaging in sections, or slices.
• Computed
– Geometric processing used to reconstruct an
image.
– Computerized algorithms
Computed Tomography (2)
• Uses X-rays
– Dense tissue, like bone, blocks x-rays.
– Gray matter weakens (attenuates) the x-rays.
– Fluid attenuates even less.
• A computerized algorithm (filtered
backprojection) reconstructs an image of each
slice.
CT Image Formation
X-ray tube
X-ray
X-ray detector
Computed Tomography
http://fitsweb.uchc.edu/student/selectives/TimHerbst/intro.htm
CT Image Formation
Backprojectio
n
fMRI
• Functional MRI – used to investigate brain
function.
• Enables watching brain activity in vivo.
• Measures haemodynamic response.
– Changes in oxygen content of the blood occur as
the result of neuronal activity.
Interdisciplinary Nature of fMRI
• Physics
– Hardware tools
• Electrophysiology
– Neuronal behaviour
• Psychology
– Cognitive psychology
• Statistics
– Making sense of observations
• Neuroanatomy