Download Neurotransmitters:

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Neurotransmitters:
the reason behind depression, addiction and all
sorts of other brain-related phenomena
You know that most every action in your body – writing your
name, saying hello, kicking a ball, playing the piano - involves
neurons in the brain sending electrical signals to each other.
When those signals are sent, an electrical impulse travels from the axon of one cell to the
dendrite of another. This signal has to cross a small gap called a synapse. Chemicals
called neurotransmitters, produced in the nerve cells themselves, are the chemical
messengers that carry these signals from one cell to another. We’ll model
neurotransmitters with Smarties!!
There are many different neurotransmitters. Two of the most interesting are dopamine
and serotonin. You’ll recall that dopamine is the brain’s “pleasure chemical”; serotonin
is a chemical that plays a large role in mood regulation and depression.
Dopamine is produced in our midbrain whenever we do something that aids our survival
either as individuals (eating, winning, acquiring possessions) or as a species
(reproducing, helping others)etc. Dopamine then helps conduct signals through a pathway
in our brain called the reward pathway – when dopamine is produced, we feel good.
http://pubs.niaaa.nih.gov/publications/arh26-2/136-142.htm
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We’ll arrange some of our neurons as part of a dopamine pathway.
Using your neuron models, try to model these steps in the normal dopamine process:
1. Dopamine is made in a cell body.
2. Dopamine travels down the axon to the
synapse.
3. Dopamine is released from the cell and
floats into the synapse.
4. Dopamine in the synapse allows the
electrical signal to pass from one cell to the
next.
5. Some dopamine is broken down in the
synapse.
6. Some dopamine is taken back into the
original cell and recycled (this is called “reuptake”).
What are some things that might go wrong
in the process you just modeled that may
result in low levels of dopamine?
There is some indication that low levels of
dopamine may be responsible for some
forms of depression or for ADHD.
The ADHD medication Adderall, for
example, is thought to speed step #1 and
slow step #5
Certain antidepressants like Wellbutrin
work by slowing the process in #6, above.
This keeps dopamine in the synapses longer.
We will model Wellbutrin’s action with raisins.
Wellbutrin molecules block some of the reuptake of dopamine; set up a
model of what this might look like in a synapse.
The longer dopamine stays in your synapses, the happier you feel!
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So far so good…but here’s the problem:
Cocaine dramatically blocks the reuptake of dopamine.
Use your materials to show what happens in a synapse under the influence of cocaine.
We will represent dopamine with Smarties.
We will represent cocaine with Navy Beans.
After the cocaine has worn off, how do you think your dopamine-producing brain cells
respond?
In terms of dopamine, then, why do people become addicted to cocaine?
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Another important neurotransmitter is serotonin. Normal levels of serotonin cause
feelings of contentment and well-being. Low levels of serotonin are a major factor in
many forms of depression.
Serotonin is also produced
in parts of your midbrain
and allows signals to be
transmitted along reward
pathways.
http://www.wellspringchiro.com/ws3_se
rotonin.jpg
Most antidepressants (Prozac, Zoloft, Paxil) are selective serotonin reuptake inhibitors
(SSRI’s). Think carefully about what each of those words means.
 Use your materials to model how an SSRI affects serotonin in your synapses.
 This time, your Smarties will represent molecules of serotonin.
 We will represent an SSRI with sunflower seeds.
Finally, The drug Ecstasy is believed to have two effects on your brain cells
 It causes higher production of serotonin.
 It blocks the reuptake of serotonin.
Use your materials to model how Ecstasy would affect your synapses. We will represent
Ecstasy with pushpins.
What then is the effect of Ecstasy on someone’s mood?
After the Ecstasy has “worn off”, how do you think brain cells might respond?
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Here is some information about these and other neurotransmitters:
Neurotransmitter
Serotonin
Norepinephrine
Dopamine
Endorphins
GABA
Acetylcholine
Adenosine
Function
Promotes
contentment
Causes
alertness,
contentment
Feelings of
contentment;
dopamine is
often produced
as a reward by
our brain after
we do
something that
aids our
survival (eating,
winning,
procreating)
Too much?
Mania?
Too little?
Depression
“Excessive”
alertness –
being “wired”
Schizophrenia
Fatigue,
depression
Natural
painkillers
released in
times of severe
pain.
Keeps nerve
cells from firing
too much, helps
you relax.
Keeps nerve
cells from firing
too much, helps
you relax, may
help initiate
sleep.
Keeps nerve
Sluggishness,
cells from firing slow responses
too much, helps
you relax.
Notes
Ecstasy blocks
serotonin reuptake.
Nicotine causes
release of this.
Depression?
Cocaine,
amphetamines block
reuptake, keeping
dopamine in our
synapses, causing
pleasurable feelings.
The body responds to
excess dopamine by
destroying it, and
when the high has
worn off, there is not
enough dopamine,
and your body craves
more. Thus, you
become addicted to
this feeling and to the
drug that helps you
produce it.
Morphine and heroin
mimic the effect of
endorphins, cause
addiction as above.
Overactive
neurons –
epileptic
seizures?
Alzheimer’s
Disease
Anesthetics greatly
enhance GABA’s
depressing effect.
High level of
brain activity
Caffeine blocks out
Adenosine, causes
high level of brain
activity.
Nicotine also causes
release of this.
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Serotonin - Smarties
Ecstasy - pushpins
Wellbutrin – raisins
SSRI’s – sunflower seeds
Dopamine - Smarties
Cocaine – Navy Beans