Download Inner Workings of the Brain

The Brain’s Inner Workings
Complexity of the Brain
Imaging the Brain
NIMH Research on the Brain and Mental Illness
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Brain Trivia
The average
number of
neurons in
the brain =
100 billion.
A newborn
baby’s brain is as
soft and gooey as
tapioca pudding!
The adult
brain
weighs
about 3
pounds.
The average number of glial cells in the
brain = 10-50 times the number of neurons.
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Complexity of the Brain
… one hundred trillion synapses
in a single human brain
organized into exquisitely complex circuits…
responding to experience, drugs,
disease, and injury…
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Complexity of the Brain
As befits the 3-pound organ of the
mind, the human brain is the most
complex structure ever investigated
by our science.
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Complexity of the Brain
The brain contains approximately 100 billion nerve cells, or
neurons, and 10 – 50 times more supporting cells, or glia.
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Complexity of the Brain
The workings of the brain depend on the
ability of nerve cells to communicate with
each other. Communication occurs at
small, specialized structures called
synapses.
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Nerve Cell
Communication
Synapse
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Complexity of the Brain
The synapse typically has two parts:
A presynaptic
structure containing
packets of signaling
chemicals, or
neurotransmitters
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and a
postsynaptic
structure on the
dendrites of the
receiving neuron
that has receptors
for the
neurotransmitter
molecules.
Complexity of the Brain
“…One of the most awe-inspiring
mysteries of brain science is how
neuronal activity within circuits
gives rise to behavior, and even
consciousness…”
Mental Health: A Report of the Surgeon General
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The Cerebral Hemispheres
The brain consists of two hemispheres.
The Left Hemisphere of the Brain:
The left hemisphere processes information sequentially and is
described as analytical because it specializes in recognizing
parts which make a whole. Although it is most efficient at
processing verbal information, language should not be
considered as being 'in' the left hemisphere. This hemisphere
is able to recognize that one stimulus comes before another
and verbal perception and generation depends on the
awareness of the sequence in which sounds occur.
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The Cerebral Hemispheres
The brain consists of two hemispheres.
The Right Hemisphere:
While the left hemisphere separates out parts that make a
whole, the right hemisphere specializes in combining the
parts to produce a whole. Unlike the left, the right
hemisphere organizes simultaneously. It specializes in a
method that perceives and constructs patterns. It is most
efficient at visual and spatial processing and it is thought
that non verbal stimuli are processed primarily in the right
hemisphere. Research into the operation of the right and
left hemispheres shows that the effective processing of
information requires access to both as they complement
each other.
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It is useful to think of the brain as containing six or seven
component parts. The largest and most advanced part
consists of the left and right cerebral hemispheres, which
appear to be more or less symmetrical. They are covered
with a layer of gray matter called the cerebral cortex.
Each of the cerebral hemispheres has traditionally been
divided into four "lobes," which are named after the
bones of the skull that surround them: frontal, parietal,
occipital, and temporal.
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The entire outer surface of the brain is called the cortex, with the forebrain area
called the frontal cortex. Those brain structures lying underneath the cortex are
termed “subcortical.”
Two sites of great interest in current brain research are the left frontal
cortex and the left temporal subcortical areas, both of which are linked
to key parts of the basal ganglia and the limbic system within the brain.
In research language, these are the “cortico-limbic” and “tempero-limbic”
circuits in the brain.
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The frontal lobe is the largest and least understood, beginning at
the front of the brain and reaching back to the central sulcus. The
area between the central and precentral sulci helps control body
movements and is called the "motor area," while the remainder of
the frontal lobe probably modulates various aspects of thinking,
feeling, imagining, and making decisions.
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The Frontal Cortex is the highest and most complex integration center
in the human brain; the essential function area for "volition," i.e.,
planning and carrying out meaningful, goal directed activities. Lesions
in the left frontal cortex create deficits in attention, abstract thinking,
foresight, mature judgment, integration of thought and perception,
reality testing, initiative, and perseverance and induce a state of pseudodepression characterized by apathy, lack of motivation, withdrawal, and
loss of sexual interest. Lesions in the right lobe have a disinhibiting
effect, revealed in wide mood swings, immature behavior,
irresponsibility, inappropriate sexual behavior and/or hypersexuality.
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The parietal lobe is the region behind the central sulcus. Part of it
is called the "somatosensory area," since it receives information
about various bodily sensations; the parietal lobe also modulates
such activities as spatial orientation. The occipital lobe recieves and
sends out visual information. The temporal lobe is perhaps the
most conspicuous lobe of the brain since it juts out from the rest
and is demarcated by the very deep Sylvan fissure. The temporal
lobe receives auditory information and controls memory and
language.
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Complexity of the Brain
The specific connectivity of circuits is, to
some degree, set in expected patterns within
the brain, leading to the notion that certain
places in the brain are specialized for
certain functions.
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Frontal Lobe:
Motor Behavior
Prefrontal
Cortex: Ability
to plan &
integrate
cognitive and
emotional
information
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Parietal Lobe: Processing of Tactile Information
Occipital Lobe:
Visual Processing
Mapping the Mind
Personality traits from shyness to impulsiveness,
scientists believe, are produced by particular
brain molecules acting on specific brain structures.
Through brain mapping and biochemistry,
researchers have identified some of them.
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Subcortical Structures of the
Limbic System

These brain areas are closely connected in
structure and function. Pathology in
schizophrenia and other major mental illnesses
is thought to lie somewhere in the complex
interconnections in the limbic system.
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Mental Disorders
Mental disorders are characterized by abnormalities in
cognition, emotion (or mood), or behavior, such as social
interactions or planning of future activities. Symptoms
related to behavior or our mental lives clearly reflect
abnormalities in brain function.
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Viewing Disorders in Action
One of the major areas in which
molecular genetics will play an
important role in the future is in
complex disorders like schizophrenia
and depression. The figure shows
areas of increased blood flow (red
hotspots) in the left amygdala and
the medial orbital cortex of a person
with familial (inherited tendencies to)
major depressive disorder.
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MRI
Magnetic resonance imaging
provides a high resolution
image of the brain's internal
structure. The scanner contains
a large magnet that induces
different chemical elements to
emit distinctive radio signals.
The signal data is translated into 2-D pictures of the brain,
slice by slice. These data can also be combined to create 3-D
views. MRI is an important tool in studies of mental illnesses
that may involve structural changes, such as schizophrenia
and ADHD.
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Functional Magnetic resonance imaging (fMRI) is a powerful tool for
studying the ever-changing activity of the brain on a moment to
moment basis. Once limited to visualizing structures, MRI has
become the leading technology for examining the living brain at work.
PET
Positron Emission Tomography is a
brain imaging technique that uses a
radioactive tracer to show chemical
activity of the brain. The PET scanner
pinpoints the destination of radioactively
tagged glucose, oxygen, or drugs to
reveal the parts of the brain involved in
performing an experimental task.
PET allows us to look at brain functions by measuring levels
of energy - or activity - in specific areas of the brain. PET
scans generate pictures of the working brain, providing maps
of emotions, learning, vision, and memory. Identifying these
brain functions is key in developing new ways to diagnose
and treat schizophrenia and other mental disorders.
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This image shows different PET scans of a forty-five-yearold woman with recurrent depression.
The scan on the left was taken when she
was on no medications and very
depressed. The scan on the right was
taken several months later when she was
well, after medication had treated her
depression. Note that her entire brain is
more active when well, particularly the
left prefrontal cortex.
Identifying brain activity associated with depression and
the changes that result from treatment and the patient's
improved mood will help to destigmatize the illness, a
disease of the brain.
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The Invisible Disease
Depression
One man in ten and one woman in five will have a serious depression
in their lives, usually before they are 40 years old.
Bipolar disorder (manic-depression) occurs in 1.2% of the
population. The majority of individuals with this illness report having
symptoms during their adolescence.
Suicide is a very high risk for this population. Tragically, 15% of
those individuals suffering from recurrent depressive disorders kill
themselves. This is a suicide rate 30 times greater than that of the
general population.
Most people with depression can be helped with treatment. But a
majority of depressed people never get the help they need. And
when depression isn’t treated, it can get worse, last longer, and
prevent you from getting the most out of life.
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Depression
Depression is
believed to
result from a
chemical
imbalance in the
brain.
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Antidepressant
drug therapy
may help
restore that
chemical
balance and
relieve
depression .
Depression
You should get evaluated by a
professional if you’ve had five or more
of the following symptoms for more
than 2 weeks or if any of these
symptoms cause such a big change that
you can’t keep up your usual routine…
1. You feel sad or cry a lot and it doesn’t go away.
2. You feel guilty for no reason; you feel like you’re no good; you’ve lost
your confidence.
3. Life seems meaningless or like nothing good is ever going to
happen again. You have a negative attitude a lot of the time,
or it seems like you have no feelings.
4. You don’t feel like doing a lot of the things you used
to enjoy - and you want to be left alone most of the time.
5. It’s hard to make up your mind. You forget lots
of things, and it’s hard to concentrate.
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Depression
You should get evaluated by a
professional if you’ve had five or more
of the following symptoms for more
than 2 weeks or if any of these
symptoms cause such a big change that
you can’t keep up your usual routine…
6. You get irritated often. Little things make you lose your temper; you over-react.
7. Your sleep pattern changes; you start sleeping a lot more or you have
trouble falling asleep at night. Or you wake up really early most mornings
and can’t get back to sleep.
8. Your eating pattern changes; you’ve lost your appetite or you eat
a lot more.
9. You feel restless and tired most of the time.
10. You think about death, or feel like you’re dying, or have
thoughts about committing suicide.
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If You’re Manic…
Some of these sound like you -
1. You’re rebellious or irritable and can’t get along at home, school, work,
or with your friends.
2. You feel high as a kite…like you’re on top of the world.
3. You get unreal ideas about the great things you can do.
4. Thoughts go racing through your head, you jump from one
subject to another, and you talk a lot.
5. You’re a non-stop party, constantly running around.
6. You do too many wild or risky things; with
driving, with spending money, with sex, etc.
7. You’re so “up” that you don’t need much sleep.
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Schizophrenia
These are MRI scans of identical twins. The twin on the right has
schizophrenia; the twin on the left is healthy. Even to the
unprofessional eye, there are obvious differences, a systematic
and consistent variation between the affected and the unaffected
twin in the gross anatomy of the brain. (Note enlarged ventricles
in the twin affected with schizophrenia)
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Source: E. Fuller Torrey, M.D., Daniel R. Weinberger, M.D.
Schizophrenia
Schizophrenia, in many ways, is the most severe of the
mental illnesses. One in every one hundred Americans has
schizophrenia. This disease, once thought to be
psychological, is clearly a brain disease. Throughout the
world, whether in Washington or New York City or in rural
Kenya, the rate of schizophrenia is still the same: one
percent of the population. Schizophrenia is a brain disease
in which vulnerability is caused by genes; something
happens during brain development that converts this
genetic vulnerability into disease. Exactly what happens is
the subject of neuroscientific research.
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Schizophrenia
In some ways, schizophrenia is like other diseases.
People who develop diabetes or heart disease have
a genetic vulnerability, and then external
circumstances convert this vulnerability into
disease. Rather than being unusual and mysterious
entities, mental illnesses are real diseases of an
organ - in this case, the brain.
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Schizophrenia
Schizophrenia is particularly tragic because its
onset usually occurs in the late teens or early 20s,
just when families, society, and educational
institutions have already put their full effort into
launching a person into the world. Tragically,
then, we lose them, often to chronic and persistent
hallucinations and delusions, fixed false beliefs
about the world, and an inability to live up to
their potential; often they withdraw from society
and lose their ability to cope with everyday life.
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Schizophrenia
Many of the symptoms of
schizophrenia are believed to be
caused by excess dopamine. Reduced
glutamate transmission which blocks
the NMDA restraining action causing
limbic structures to release more and
more dopamine could be the ultimate
cause.
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Step On A Crack-
OCD
About 2.3% of the U.S. population ages 18-54
(approximately 3.3 million) has obsessive-compulsive
disorder in a given year.
People with OCD suffer intensely from recurrent, unwanted thoughts
(obsessions) or rituals (compulsions), which they feel they cannot control.
Rituals, such as handwashing, counting, checking, or cleaning are often
performed in hope of preventing obsessive thoughts or making them go away.
Performing these rituals, however, provides only temporary relief, and not
performing them markedly increases anxiety. Left untreated, obsessions and
the need to perform rituals can take over a person’s life. OCD is often a chronic,
relapsing illness.
OCD affects men and women equally.
OCD typically begins during adolescence or early childhood;
at least one-third of the cases of adult OCD began in childhood.
OCD cost the U.S. $8.4 billion in 1990 in social and economic
losses, nearly 6% of the total mental health bill of $148 billion.
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Persons with OCD use
different brain circuitry in
performing a cognitive task
than people without the
disorder.
Rauch SL, et al. J Neuropsychiatry
Clin Neurosci, 1997: 9:568-573.
There is growing evidence that OCD has a neurobiological basis. The
search for causes now focuses on the interaction of neurobiological
factors and environmental influences. Brain imaging studies using PET
scans have compared people with and without OCD. Those with OCD
have patterns of brain activity that differ from people with other mental
illnesses or people with no mental illness at all. PET scans also show that
both behavioral therapy and medication produce changes in the
caudate nucleus.
This is graphic evidence that both psychotherapy and medication affect
the brain.
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This presentation produced by
Velma Beale, Ohio NIMH Outreach Coordinator, NAMI Ohio,
with materials from:
Mental Health: A Report of the Surgeon General;
the NIMH website and publications; and the
NAMI Family-to-Family education course.
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For Further
Visit these websites:
Information:
http://www.nami.org
http://www.nimh.nih.gov
http://www.namiohio.com
E-mail
Ohio NIMH Outreach Coordinator: [email protected]
NAMI Ohio: [email protected]
NIMH: [email protected]
Or call
the Ohio NIMH Outreach Coordinator: 740-599-5266
NAMI Ohio: 614-444-AMIO
NAMI Ohio hotline (in Ohio): 1-800-686-AMIO
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