Psychologists study the brain and nervous system to understand how biological functions influence human behavior. Some psychologists called behavioral neuroscientists specialize in studying the effects of biological processes like neurotransmitters on behavior. Neurotransmitters are chemicals that transmit signals between neurons in the brain and body. An imbalance of neurotransmitters can impact mood, movement, memory formation and other behaviors, and may be linked to conditions like depression, Parkinson's disease, and schizophrenia. Brain imaging techniques like PET and SPECT scans can detect abnormal levels of neurotransmitter activity and production in the brain.

1. Biology
Neurotransmitters

2. Pair-share
How do you think chemicals in
our bodies impact our behavior?
(Discuss with your table partner).

3. Nervous System
Q: Why do psychologists study the brain and the
nervous system?
A: Some biological functions underly human behavior,
and in order to form a fuller understanding of ourselves,
it’s important to recognize what aspects of our behavior we
can attribute to our own bodies.
Psychologists who examine behavioral problems based on the
ways in which our bodies affect our behavior are using the
“biological” or “neuroscience” approach. Psychologists who
specialize in studying the effects of biological functions on
behavior are called “behavioral neuroscientists.”

4. Nervous System
You have about
1 trillion nerve
cells in your
body, and 100
chemicals that
transfer
messages
between those
nerves.
(Those chemicals
are called
neurotransmitters).

5. Nerve Ending (outgoing)
Neurotransmitters
Neurotransmitters stimulate the nerve endings, or
transmit electrical impulses from the brain to the body.
Nerve Ending (incoming)
Neurotransmitters
(Chemicals that travel
between neurons)
(Axon)
(Dendrite)
Synapse
(gap)

7. Neurotransmitters
Neurotransmitter Name Function
Acetylchloline Movement control, thinking/comprehending
Glutamate Memory
Gamma-amino butyric
acid (GABA)
Eating, sleeping, aggression
Dopamine
Movement control, attention,
pleasure and reward feelings
Serotonin
Eating, sleeping, mood, pain, depression,
coping with stress
Endorphins
Pain suppression, pleasurable feelings,
appetite

8. Neurotransmitters
An excess or lack of neurotransmitters
can impact our behavior.
For example, Parkinson’s
Disease causes the brain
cells that produce
dopamine to die.The
lack of dopamine in the
body leads to shaking,
irregular movements, and
loss of motion control.
Lack of dopamine also
depresses your mood,
which affects your
personality and habits.

9. Neurotransmitters
An excess or lack of neurotransmitters
can impact our behavior.
Dopamine is also
associated with
motivation and
reward. When we
do things like eating,
exercise, and
romancing,
dopamine is released
in our brains.
Too much is also bad: studies show that
unusually high amounts of dopamine in
our bodies is related to schizophrenia.

10. Drugs & The Brain
Certain drugs like cocaine cause a temporary
overproduction of dopamine, mimicking the reward
sensation. In other words, cocaine gives you a greater
feeling of reward than the things that naturally cause
dopamine production.The result of this is addiction.
DopamineRelease
DopamineRelease
Time Time
Cocaine
Exercise, eating,
kissing/sex,
winning

11. Neurotransmitters
Endorphins block pain in your body, and are also
responsible for feelings of pleasure or happiness. A lack
of endorphins may be responsible for certain forms of
mental illness such as obsessive-compulsive disorder.
Endorphins are released
when you exercise, and also
when you experience pain.
Some people who engage in
self-hurting behaviors may
do so in part to feel the
feelings of euphoria
prompted by controlled
amounts of self-inflicted pain.

12. Neurotransmitters
Acetylcholine deficiency is an
abnormally low level of
acetylcholine.This
neurotransmitter is involved in
the control of muscle movement,
learning, and memory formation.
A lack of it causes uncontrolled
muscle movements and difficulty
forming and retrieving memories. Serotonin is a
neurotransmitter greatly
involved in your mood. If you’re
feeling pessimistic, sad,
distrustful, unconfident, or have
panic attacks, you may have a
serotonin deficiency.

13. Neurotransmitters
Today in modern medicine, drugs that stimulate
neurotransmitter production are being tested to see if
they help relieve symptoms of clinical depression.
Symptoms of depression:
Loss of interest
Loss of appetite
Loss of energy
Feelings of loneliness
Feelings of worthlessness
Anger or irritability
Concentration problems
Reckless behavior

14. Causes
What causes you to have too much or too little
of a neurotransmitter in your body?
Genetics:
If family members
have a chemical
deficiency, it may
be passed on
genetically.
Poor
Nutrition:
Your diet impacts
your bodily
chemicals (and
obesity does too).
Stress:
Stress can raise
or lower
certain your
bodily
chemicals.
Disease:
Related to genetics:
Parkinson’s,
Alzheimer’s,
and other diseases
cause chemical
imbalances.
Drugs:
Taking certain
drugs confuses
your body into
releasing chemicals
when it has no
natural reason to.
Lack of
Exercise:
Can cause problems
like high blood
pressure that
lowers blood-flow
to your brain.
Alcohol,
Smoking:
Both cause
direct damage to
the brain tissues.
Lack of
Sleep:
Lowers blood
flow to your
brain.

15. Brain
Imaging

16. Brain Imaging
Two types of brain scans - PET scans and SPECT scans -
show how much activity is going on in the brain.
“Activity” is measured by neurons firing, increased blood
flow, and/or release of brain chemicals.
This is a PET scan. After
scanning thousands of
brains, researchers identified
what “normal” levels of
brain activity looks like. If a
brain shows activity higher
or lower than a normal
brain, we know there is
something wrong.

17. Brain Imaging
Two types of brain scans - PET scans and SPECT scans -
show how much activity is going on in the brain.
“Activity” is measured by neurons firing, increased blood
flow, and/or release of brain chemicals.
This is a SPECT scan.
The healthy brain
will have a smoother
shape with even brain
activity. A brain with
problems will be
shaped with holes or
lumps.

18. Brain Imaging
Two types of brain scans - PET scans and SPECT scans -
show how much activity is going on in the brain.
“Activity” is measured by neurons firing, increased blood
flow, and/or release of brain chemicals.
For example, a
SPECT scan can
help us see if a
person’s brain is
not producing
enough of a
neurotransmitter,
or is producing
too much.