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NEUROTRANSMITTERS
Biological Bases of Behavior
If part of your brain is damaged, you might experience memory loss, changes in how you perceive the world,
delusions, hallucinations, major personality changes, or many other symptoms.
If your brain has too much of one neurochemical, you'll lose touch with reality; not enough of a different substance,
you're likely to suffer insomnia.
Biological or physiological psychologists study the relationship between biology and behavior. The biological
perspective examines how heredity and physiological structures affect mental processes and overt actions,
considering how chemical processes and physical mechanisms affect emotions, thoughts, desires, and sensory
experience. Related terms include biopsychology, psychophysiology, and neuroscience.
Everything Psychological is Simultaneously biological!
Neurotransmitters
Serotonin - sleep, depression
(Prozac is a selective seroton reuptake inhibitor)
Acetylcholine - neuromuscular junctions, implicated in Alzheimer’s
Endorphins - beta-endorphin - “natural opiate” - effects similar to morphine
GABA - inhibitory
Dopamine - Parkinson’s disease & Schizophrenia
Epinephrine/norepinephrine - Arousal, wakefullness, depression (catecholamine theory of depression - MAO
inhibitors increase levels)
Agonist drug effects
A drug that mimics or increases the effects of a neurotransmitter
Antagonistic drug effects
A drug that blocks the effects
of a neurotransmitter
Excitatory neurotransmitters excite cells to make actions happen. Inhibitory neurotransmitters reduce different
kinds of activity to keep them under control.
For example, acetylcholine increases muscular activity but dopamine decreases it. Too much acetylcholine might
cause trembling, whereas too little dopamine may mean there is not enough to prevent trembling.
Types of Neurotransmitters in Detail
The most prevalent neurotransmitter in the human body is ACETYLCHOLINE, which yields a wide variety of
functions, including movement (whether voluntary or involuntary), thought, and memory formation. Acetylcholine is
essential for both muscular movement and memory formation.
Deficiency: The drug scopolamine blocks acetylcholine receptor sites to interfere with memory formation. Curare
blocks other acetylcholine receptors to produce a paralysis so thorough that without artificial respiration, the person
promptly suffocates to death. It has been found that Alzheimer's patients do not have as much acetylcholine in
their brains as will be found in other people's brains. (The relationship between Alzheimer's and acetylcholine still
is not understood, however, because raising acetylcholine levels will not clear up the individual's senile dementia.)
Excess: While having blocked or insufficient acetylcholine causes certain problems, getting too much too fast will
cause other problems. Most nerve gases have their effects by making the body release its acetylcholine too fast,
thereby producing respiratory seizures.
DOPAMINE prevents excessive muscular activity and allows the individual to control his or her own actions. It also
plays some role in thought and emotion.
Deficiency: People with Parkinson's disease do not have enough dopamine in their brains. The most obvious
symptoms are tremors and shaking. They may difficulty initiating actions or stopping actions they've already
started: One moment the person might have trouble taking the first step to start walking, then later might walk into
a wall because the feet won't stop. Emotional symptoms include an elevated depression rate. Emotional
expressiveness appears reduced because facial muscles do not properly reflect the person's emotions. Drugs like
L-dopa can alleviate symptoms of Parkinson's by having the same effects as dopamine.
Excess: Many individuals with schizophrenia have been found to have too much dopamine in their brains.
Uncontrolled activity throughout the brain makes the schizophrenic individual lose touch with reality and act in
bizarre ways. Most antipsychotic drugs, therefore, act to reduce schizophrenic symptoms by reducing dopamine
levels. As a side effect, however, the antipsychotic drugs can eventually produce symptoms like those of
Parkinson's, a condition known as tardive dyskinesia.
SEROTONIN produces sleep by inhibiting the systems involved in keeping the individual awake. The longer you
stay awake, the more your serotonin levels build up. Did you ever wake up wrong, with your head groggy and still
full of sleep? Serotonin is doing that to you.
Deficiency: Serotonin deficiency may very well play a role in a wider variety of mental illnesses than any other
single variable. Without enough serotonin to calm the brain, individuals may suffer many different ailments,
particularly those that involve anxiety, obsessions, compulsions, or insomnia. Drugs known as selective serotonin
reuptake inhibitors (SSRIs) help the brain use its serotonin more effectively. If obsessing over unpleasant thoughts
plays a role in one's depression, the SSRIs can prove valuable as antidepressants, although simply regulating
brain chemistry alone does not help the person learn new habits. When medication is needed to fix a problem with
brain chemistry, the individual probably still needs counseling or behavioral retraining.
Excess: Having too much serotonin is likely to make the individual sleepy, sluggish, and unmotivated. It can
interfere with the ability to focus attention and think clearly. Depression is a common problem among individuals
with excessive serotonin, which is why some depressed individuals should avoid SSRIs -- they absolutely do not
need to make their natural serotonin more powerful. Excessive serotonin is likely to produce hypersomnia,
excessive sleep.
GABA (an acronym standing for gamma-amino-butyric acid) is an amino acid that acts as a neurotransmitter. It is
involved in most behaviors, including anxiety states. This inhibitory neurotransmitter reduces the brain's electrical
activity. The brain needs its electrical activity, of course, but too much can produce many problems.
Deficiency: Among the various problems related to GABA deficits are anxiety and epilepsy. Without enough GABA,
brain cells fire more than they should and keep the brain charged up. Some individuals without enough GABA will
have epileptic seizures, which involve chain reactions of electrical discharges in the brain setting off more electrical
discharges in the brain (like chain lightning, when lightning in one cloud sets off lightning discharges in other
clouds).
Excess: Having too much could leave the individual unmotivated, sluggish of thought, and experiencing many
other symptoms.
NOREPINEPHRINE, also known as NORADRENALINE
EPINEPHRINE, also known as ADRENALINE
Adrenaline and noradrenaline both excite the nervous system very broadly with many similarities between the two
different neurotransmitters. The difference may be likened to the kinds of arousal associated with the fight or flight
response: Noradrenaline activates the individual to charge forward, whereas adrenaline inspires retreat.
Noradrenaline tends to be associated with more pleasant kinds of arousal. Adrenaline can also be pleasant, but
too much is likely to produce anxiety and jittery feelings. Adrenaline also helps you breathe more easily, fighting
symptoms of asthma and allergies. In the movie Pulp Fiction, a character whose heart has stopped gets a jump
start from a shot of adrenaline directly into the heart.
Deficiency: Having too little, you're likely to feel underaroused, unmotivated, or sleepy, and will be susceptible to
headaches.
Excess: Cocaine speeds up the release of both, especially noradrenaline. In fact, it makes the body releases its
noradrenaline so fast that the individual will "crash" and feel unpleasantly underaroused after the high is over -essentially, it produces a quick episode of manic depression. Caffeine speeds up the release of both, especially
adrenaline. This is why too much coffee can make you jittery. Some individuals with anxiety disorders have too
much adrenaline. Even if they do not, they should avoid caffeine intake to keep from compounding their anxious
symptoms.
SUBSTANCE P lets us feel pain.
Deficiency: If you don't feel pain, you might fail to protect yourself from injury, or you might neglect treatment of
injuries you incur.
Excess: With too much substance P, you could feel pain too intensely.
The ENDORPHINS (short for "endogenous morphines") are a group of neuropeptides (chains of amino acids
which act as neurotransmitters) that inhibit certain synaptic transmissions, particularly those involving pain. As
mentioned above, drugs like morphine mimic the actions of the endorphins. The body releases endorphins when
you laugh, when you're sexually excited, and when you experience many other kinds of pleasurable sensations.
The body also releases endorphins to make you feel better when the body undergoes pain or stress, as in the
"runner's high" people might achieve after running for a prolonged period.
Deficiency: Without enough endorphins, you will have trouble resisting pain. You are also likely to suffer immune
system problems and be more susceptible to illness. Plus, you might not have as good a sense of humor.
Excess: With too much, you will feel no pain -- "pleasantly numb," so to speak. Frequent release of endorphins
could get you hooked on the endorphin-releasing activities. Some people will exercise excessively, doing more
damage than good to themselves, because the endorphins feel good and make them less aware of the stress to
their bodies. People with trichotillomania (compulsive hair pulling) and sexual masochism (habitually yearning for
pain to achieve sexual gratification) may be addicted to the endorphin release produced by these painful activities.
ENKEPHALINS are a subgroup of the endorphins.