Cerebral Cortex -The largest division of the brain.
It is divided into two hemispheres, each of which is
divided into four lobes.
Cerebral
Cortex
Cerebral
Cortex
Cerebellum
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
Lobes of the Brain (4)
•
•
•
•
Frontal
Parietal
Occipital
Temporal
http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Cerebral Cortex (lobes)
Divided into 4 lobes:
Frontal: motor function,
motivation, aggression, smell
and mood
Parietal: reception and
evaluation of sensory info.
Temporal: smell, hearing,
memory and abstract
thought
Occipital: visual processing
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
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
Frontal Lobe - Cortical Regions
• Prefrontal Cortex – Cortical region involved in planning
complex cognitive behavior, personality expression, decision
making, and moderating social behavior.
• Premotor Cortex – Contributes to motor functions
• Primary Motor Cortex – 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.
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
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Lobes of the Brain - Parietal Lobe
Somatosensory cortex:
• It plays a major role in the following functions/actions:
- Senses and integrates sensation(s)
- Spatial awareness and perception
(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
Lobes of the Brain – Temporal Lobe
• Primary Auditory Cortex
• 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
• 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
Lobes of the Brain – Occipital Lobe
• Its primary function is the
processing, integration,
interpretation, etc. of VISION and
visual stimuli.
• Primary Visual Cortex – This is
the primary area of the brain
responsible for sight recognition of size, color, light,
motion, dimensions, etc.
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Primary Visual
Cortex
Visual
Association Area
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Regions
The strange case of Phineous Gage
Phineous Gage
•
•
•
•
Railroad foreman
Well-respected, hard-working
1848: tamping iron accident
He never lost consciousness, and had no
obvious neurological symptoms
• But he was “no longer Gage”
Phineas Gage
“the powder exploded, carrying an iron instrument
through his head an inch and a fourth in
circumference, and three feet and eight inches in
length, which he was using at the time. The iron
entered on the side of his face, shattering the upper
jaw, and passing back of the left eye, and out at the
top of the head.
The most singular circumstances connected
with this melancholy affair is, that he was alive at
two o’clock this afternoon, and in full possession of
his reason, and free from pain.”
– from Free Soil Union, September 1948
Phineous Gage
Gage’s Doctor described Gage’s post-accident
personality as:
“Fitful, irreverent, indulging at times in the greatest profanity which was not
previously his custom, manifesting but little deference for his fellows,
impatient of restraint and advice when it conflicts with his desires, at times
pertinaciously obstinate, yet capricious and vacillating, devising many plans of
future operation, which are no sooner arranged than they are abandoned … a
child in his intellectual capacity and manifestations, he has the animal
passions of a strong man.”
Brain Anatomy - Phineas Gage
•Personality changed – Gage became crude,
uncaring, impulsive, irrational, anti-social
•Ventromedial region of the frontal lobes on
both sides - causing a defect in rational decision
making and the processing of emotion
“The equilibrium or balance between his intellectual
faculties and animal propensities, seems to have been
destroyed.” (Former R.R. Employer)
“He was no longer Gage…”
• Several different
angles of where the
rod passed through
his skull
Some symptoms associated with
frontal lobe damage
•Working memory deficits
•Temporal memory / Source memory
•Perseveration
•Loss of spontaneous behavior
•Apathy
•Planning deficits/impaired goal-directed behavior
•Disinhibition/impulsive behavior
•Impaired attention
•Depression
•Elevated mood
Mood/Affect/Emotion Symptoms
• Depression
• Mood elevation
• Apathy
Frontal Lobotomies
• 1935: chimps who were neurotic before surgery
became more relaxed after it
• 1930s: Egaz Moniz begins frontal lobotomies in
humans (and eventually wins Nobel Prize)
• 1950s: psychosurgery in vogue; 40,000 frontal
lobotomies in North America
• The story of Agnes (Kolb & Whishaw)
– no outward signs of emotion
– no facial expression
– no feelings toward other people (but still liked her
dog)
– felt empty, zombie-like
– Other patients lose prosody = emotional component
of speech
• orbitofrontal cortex
– Patients with damage can remember info but don’t
have emotions associated with it
Frontal Lobe
Lobotomy: Early Critisicms
Hoffman (1949)
– "these patients are not only no longer distressed by
their mental conflicts but also seem to have little
capacity for any emotional experiences - pleasurable or
otherwise. They are described by the nurses and the
doctors, over and over, as dull, apathetic, listless,
without drive or initiative, flat, lethargic, placid and
unconcerned, childlike, docile, needing pushing,
passive, lacking in spontaneity, without aim or purpose,
preoccupied and dependent."
Frontal Lobe
Frontal Lobe Damage
• May have normal IQ on standard tests
• Poor control: reasoning, planning & emotions
– Disinhibition: poor control of emotions
• Poor mental flexibility
– Perseveration: e.g. trouble stopping action once
initiated, e.g. dialing 999.
• Frontal lobe modulates functions of other
regions