Psychology 12
The Divided Brain…
 VIEW
Documentary: History Channel
“The Brain”
 We
begin our exploration of
the brain at the lower end,
where the spinal cord joins the
base of the brain, and then
continue upward toward the
skull.
 Note that as we move from
bottom to top, “lower,” basic
processes like breathing
generally give way to
“higher,” more complex
mental processes.
 The
brain is the control center of the
body.
 It is made up of dense "grey matter"
consisting of complicated networks of
interconnected neurons
 The brain can be superficially divided
into three main parts: the hindbrain, the
midbrain and the forebrain.
 The
brain can be
divided into THREE
major sections: the
hindbrain,
midbrain, and
forebrain.
 Also, the
large
section labeled as the
BRAINSTEM includes
parts of all three of
these 3 sections
 It helps regulate
reflex activities
important to
survival (i.e.,
heartbeat and
respiration)
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Running through the core of the
hindbrain, midbrain, and
brainstem is the reticular
(netlike) formation (RF).
This finger-shaped network of
neurons filters incoming
sensory information and alerts
the higher brain centers to
important events.
Without your RF, you would not
be alert or perhaps even
conscious.
In fact, some general anesthetic
target the RF so pain sensations
never register in the brain.
Throughout the tour,
note that certain brain
structures are
specialized to perform
certain tasks, a process
known as localization
of function
 BUT also note that
most parts of the brain
are not so
specialized—they
perform overlapping
functions.

It has been recognized for a very long time that if
someone damaged their brain, then they might
show some sort of functional deficit
 And that someone else who damaged their brain
in a similar area would most likely show similar
deficits.
 Conversely, two people with brain damage in
different areas may well show very different
deficits.
 This, of course, suggests that, at least to some
extent, function is localized within the brain
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Have you ever wondered what allows you to
automatically breathe and your heart to keep
pumping
automatic behaviours and survival responses like
these are either controlled by or influenced by parts
of your hindbrain, which includes the medulla, pons
and cerebellum.
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Medulla: Essentially is an extension of the spinal cord,
with many nerve fibers passing through it carrying
information to an from the brain.
It also controls many essential automatic brain
functions like respiration and heartbeat.
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Cerebellum: (“little brain”) is evolutionarily, a very
old structure.
It coordinates fine muscle movement and balance.
The cerebellum coordinates the muscles so that
movement is smooth and precise.
It is also crucial for our sense of balance and
equilibrium
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Pons: Located above the cerebellum and medulla, is
involved in respiration, movement, sleeping, waking,
and dreaming (among other things).
It also contains many axons that cross from one side
to the other (pons is Latin for “bridge”)
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The midbrain is the small
part of the brain that helps
orient our eye and body
movements to visual and
auditory stimuli, and works
with the pons to help control
sleep and level of arousal.
It also contains a small
structure involved with the
neurotransmitter dopamine,
while deteriorates in
Parkinson’s disease.
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The Forebrain is the largest
and most prominent part of
the human brain. It includes
the thalamus,
hypothalamus, limbic
system, and cerebral
cortex.
The first three structures are
located near the top of the
brainstem.
Wrapped around them is the
cerebral cortex (cerebral is
Latin for “brain,” and cortex is
Latin for “covering”)
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Thalamus: Resembling two
little footballs jointed side by
side, the thalamus serves the
major sensory relay center for
the brain.
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Like an air traffic control centre
that receives information from all
aircraft and then directs them to
the appropriate landing or
takeoff areas
The thalamus receives input from
nearly all the sensory systems
and then directs this information
to the appropriate areas.
For example, while you are
reading this, your thalamus
sends incoming visual signals to
the visual area of your cortex.
While listening to music, the
information is transferred to the
auditory area of the cortex.
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The thalamus receives input
from nearly all the sensory
systems and then directs this
information to the appropriate
areas.
For example, while you are
reading this, your thalamus
sends incoming visual signals
to the visual area of your
cortex.
While listening to music, the
information is transferred to
the auditory area of the
cortex.
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Thalamus: Integrates input from
the senses
Thalamus: In addition to
relaying sensory information
to the cortex it also integrates
information from various
senses and maybe involved in
learning and memory.
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Thalamus: Integrates input from
the senses
Injury to the thalamus can
cause deafness, blindness, or
loss of any other sense
(except smell).
Damage may cause the
cortex to misinterpret or not
receive vital sensory info.
Interestingly, brain-imaging
research links thalamus
abnormalities to
schizophrenia (a serious
psychological disorder
involving problems with
sensory filtering and
perception).
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Hypothalamus: Controls
basic drives, such as
hunger
Hypothalamus: Beneath the
thalamus lies the
hypothalamus (“hypo”
meaning “under”). Although
no larger than a kidney bean,
it has been called the master
control centre” for basic
drives such as hunger, thirst,
sex, and aggression.
It also helps govern hormonal
processes by regulating the
endocrine system.
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Limbic System: Regulates
fear and other emotions
Limbic System:
An interconnected group of
forebrain structures is located
roughly along the border
between the cerebral cortex and
the lower-level brain structures
(hence the term “limbic,” which
means “edge” or “border”).
Structures include the
hippocampus, amygdala,
thalamus, hypothalamus.
Responsible for emotions,
drives, and memory, and
involved in forming and
retrieving memories.

Limbic System: Regulates
fear and other emotions
Limbic System: The major
focus of interest in the limbic
system, and particularly the
amygdala, has been its
production and regulation of
emotions (e.g.. aggression
and fear)
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Limbic System: Regulates
fear and other emotions
Amygdala: Also known for its
role in pleasure or reward.
A study done with rats—
stimulating certain areas of
the limbic system—cause a
”pleasure” response. The
feeling was so rewarding that
he rats would cross electrified
grids, swim through water
(which they normally avoid),
and press a lever thousands of
times until they collapsed
from exhaustion—just to have
this area of their brains
stimulated.
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Cerebral Cortex: Governs
higher mental processes, such
as thinking
Cerebral Cortex: The centre
for “higher” processing.
The gray, wrinkled cerebral
cortex is responsible for most
complex behaviours and
higher mental processes.
It plays such a vital role in
human life that may consider
it the essence of life.
Without a functioning cortex,
we would be almost
completely unaware of
ourselves and our
surroundings.
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Cerebral Cortex: Convolutions
Although it is only about
¼ inch thick, it is made up of
approximately 30 billion
neurons and nine times as many
supporting cells.
When spread out, the cortex
would cover an area almost the
size of a standard newspaper
page.
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Cerebral Cortex: Convolutions
How does your cortex, along
with all your brain structures fit
inside your skull?
Imagine crumpling and rolling
a newspaper sheet into a ball—
you would retain the same
surface area, but in a much
smaller space.
The cortex contains “wrinkles”
called “convolutions” allowing
it to hold billions of neurons in
the restricted space of the skull.
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Cerebral Cortex: Hemispheres
If you’ve ever watch brain
surgery on TV—once the skull
has been opened, you’ll first
see a gray, wrinkled, cerebral
cortex that closely resembles
an oversized walnut.
Like a walnut, the cortex has a
similar division (fissure) down
the centre, which marks the left
and right hemispheres of the
brain.
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Cerebral Cortex: Hemispheres
The hemispheres are
connected by a band of fibers
called the corpus callosum.
The two hemispheres make up
about 80% of the brain’s weight
and they are mostly filled with
axon connections between the
cortex and other brain
structures
Each hemisphere controls the
opposite side of the body
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Cerebral Cortex: Hemispheres & Lobes of the Brain
The two cerebral hemispheres are divided into eight distinct
areas, or lobes—four in each hemisphere. Like the lowerlevel brain structures, each lobe specializes in somewhat
different tasks—another example of localization of function.
However, some functions overlap between lobes.
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Cerebral Cortex: Lobes
Frontal Lobe: Receives and coordinates messages from
other lobes; motor control, speech production, and
higher functions. Includes the motor cortex which
controls voluntary movements and Broca’s area which
controls speech production
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Cerebral Cortex: Lobes
Parietal Lobe: Receives information about pressure,
pain, touch, and temperature. Includes the
Somatosensory cortex which receives sensory
messages.
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Cerebral Cortex: Lobes
Occipital Lobe: visual perception and vision—includes
the Visual cortex that receives and processes visual
information
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Cerebral Cortex: Lobes
Temporal Lobe: Hearing, language, comprehension,
memory, and some emotional control—includes
Wernicke’s area that controls language comprehension
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Cerebral Cortex: Frontal Lobes
The largest of the lobes, the two frontal lobes are located
at the top front portion of the brain hemispheres—right
behind your forehead.
They receive and coordinate messages from all other
lobes, while also being responsible for at least 3 other
functions:
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Cerebral Cortex: Frontal Lobes
. Higher functions—functions that distinguish us from
other animals, such as thinking, personality, emotion,
and memory.
Damage to the frontal lobes affect motivation, drives,
creativity, self-awareness, initiative, reasoning, and
emotional behaviour.
Abnormalities in FL are often observed in patients with
schizophrenia
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Cerebral Cortex: Frontal Lobes
Speech Production: In the left frontal lobe, on the
surface of the cortex near the bottom of the motor
control area lies Broca’s area, which is known to play a
crucial role in speech production.
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Cerebral Cortex: Frontal Lobes
Motor Control: At the very back of the frontal lobes lies
the motor cortex, which sends messages to the various
muscles that instigate voluntary movement.
When you call a friend on a cell phone, the motor control
area of your frontal lobes guides your fingers to press
the desired sequence of numbers.
Cerebral Cortex: Parietal Lobes
At the top of the brain, just behind the frontal lobes, are the
two parietal lobes. They contain the somatosensory
cortex, which interpret bodily sensations including
pressure, pain, touch, temperature, and location of body
parts.
When you step on a sharp nail, you quickly (and reflexively)
withdraw your foot because the messages travel directly
to and from your spinal cord. However, you do not
experience “pain” until the neural messages reach the
parietal lobes of the brain.
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Cerebral Cortex: Temporal Lobes
The two temporal lobes (Latin for “pertaining to the
temples”)are responsible for auditory perception
(hearing), language comprehension, memory, and
some emotional control.
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Cerebral Cortex: Temporal Lobes
The auditory cortex (which processes sound) is located
at the top front of each temporal lobe.
This area processes incoming sensory information from
the ears and sends it to the parietal lobes, where it is
combined with visual and other sensory info.
In the LEFT temporal lobe, Wernicke’s area is involved in
language comprehension.
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Cerebral Cortex: Occipital Lobes
(Latin “oh,” “in the back of,” and “caput,” “head”)—
located at the lower back of the brain. Occipital lobes
are responsible for vision and visual perception.
Damage to this area can produce blindness, even
though the eyes and their neural connection to the brain
are perfectly healthy.
The occipital lobes are involved in shape, colour, motion,
and perception.
 Split-Brain
Surgery:
Cutting of the corpus
callosum to separate
the brain’s two
hemispheres.
 When used medically
to treat severe
epilepsy, split-brain
patients provide data
on the functions of
the two hemispheres.
 This
information has
profoundly improved
our understanding of
how the two halves of
the brain function.
Hemispheric Specialization: although complex activities
occur in both hemispheres, specialization of function occurs in
some areas
Right Hemisphere
1.
Nonverbal Abilities: Music,
Left Hemisphere:
art, perceptual and spatio1.
Language Functions:
manipulative skills,
speaking, reading,
recognition of faces,
writing, and
patterns and melodies,
some language
understanding
comprehension
language
2.
Emotions: Associated with
2.
Emotions: Associated
negative emotions, emotion
with positive emotions
expression, and emotion
perception
3.
Analytical: Figures
3.
Synthetic: figures things out
things out step by step
by combining to form
4.
Controls and senses
wholes
the right side of the
4.
Controls and senses the left
body
side of the body.

 Imagine
yourself as a high school football
player (not too difficult for some!). If you
suffered a concussion while playing a
game, would you tell your coach?
There is mounting
evidence linking
multiple concussions
with permanent (and
possibly fatal) brain
damage…
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According to a report,
“many of the 1.2
million teenagers who
play high school
football either don’t
know what a
concussion is or they
simply don’t care.
They continue to play
on and get hurt much
worse—sometimes
fatally.”
Millions of people suffer head injuries each year, and
most of these injuries are minor—thanks to the bony
skull’s protection for the brain. This is not the case
for traumatic brain injuries (TBI).
 TBI is defined as an injury to the brain caused by
significant trauma
 Symptoms: (range from mild to severe): headache,
loss of consciousness, convulsions, coma and death.
 Two most common brain injuries are concussions
(result from significant blow to the head) and
contusions (bruises to the brain). Either TBI can
result in prolonged or nonreversible brain damage
and serious problems, such as extreme changes in
personality, significant loss of motor skills, emotional
control, and mental abilities

 Let’s
work with our
right hemispheric
spatiomanipulative
skills—we are going
to build a 3-D
version of the brain.
Objective: To gain a better understanding
of the location and function of the parts of
the brain
Using your textbook, the slides and
the chart you created yesterday as
guides, create a 3-D cross section of
the left side of the brain, making
sure to include all the structures
listed in your charts (obviously,
none from the right hemisphere)
Use a numbering system on the
appropriate sections of the brain
(attached with sticky notes &
toothpicks) and write the
corresponding names of the
structures and their functions on
card stock (recipe cards)..
A) Questions: Answer questions 3, 4 & 5 on
page 168.
B) Read the Case Study on page 169
Answer the following questions:
 How does split-brain surgery benefit both the
patient and humans in general? Should splitbrain surgery ever be performed on a person
with no brain disorders?
 Complete questions 1-3 from the case study.
 Read
the Time article
on page 180-1.
 Answer
the Analyzing
the Article Questions
1-2