Biology 202
2000 First Web Report
On Serendip

When alcohol is inputted into our brain, it induces many forms of typical behavior outputs such as impaired judgement, extreme emotion, and slowed behavior. Long-term effects include damage in cognitive behavior especially associated with the frontal lobes of the brain such as "slowed processing of information, difficulty in learning new material, deficits in abstraction and problem solving, and reduced visuospatial abilities." (1). The reason for this kind of damage in cognitive behavior can be explained the alcohols effect on the brain structure itself. Researchers have found that brains of alcoholics are smaller and have an increased number of brain tissue loss then the comparable nonalcoholic. Known as the premature aging hypothesis, alcohol is stated to "accelerate normal aging" and make the young alcoholics older then they really are. This kind of aging due to alcohol allows the younger non-alcoholics of the same age, faster and quicker in cognitive abilities. (1)

So what is the underlying mechanisms of this kind of output behavior? What goes on inside the boxes within boxes that cause actions such as slow cognitive output? These behavioral outputs can be explained from alcohol's effects on the humans' smallest box, the neuron. With alcohol, the neuron's and chemical messengers involved in signaling is depleted and interfered. Specific chemical messengers effected by alcohol are the neurotransmitter serotonin (5 HT), gamma-aminobutyric acid (GABA), and dopamine.

The role of neurotransmitters in the brain is to either stimulate or inhibit the flow of an impulse between neurons. The GABA is an example of a neurotransmitter that is used as an inhibitor, where the 5 HT and dopamine can have either function of stimulating or inhibiting impulse, depending on what area of the brain it is at. All three neurotransmitters are involved in influencing some type of behavior through their inhibition or stimulation. The 5 HT for example, is known to have the most diverse functions in influencing all kinds of behavior. The influence of behavior is caused by the binding of the serotonin to its receptor, which then stimulates small molecules to form within the cell, which then in turn act with other proteins to activate various cellular functions. These cellular functions result in either stimuli or inhibition and "through these mechanisms, serotinin can influence mood states, thinking patterns, emotion and motivation." (2). The 5 HT also "appear to involve control of appetite, sleep, memory and learning, temperature regulation, mood, behavior, cardiovascular function, muscle contraction, endocrine regulation, and depression." (2 ).

Although not as diverse as the 5 HT, the GABA and dopamine are also involved in influencing certain behaviors. Many GABA neurons for example, are found in the hippocampal formation, which is a part of brain that is important in memory and other cognitive functions. The dopamine, on the other hand is found in brain regions called the ventral tegmental area which is a region involved in producing pleasure and reward.

The input of alcohol into the brain on these three neurotransmitters produces much interference that result in certain output behavior. These interferences can involve either the individual neurotransmitter or the interactions of the neurotransmitters working together. One form of interference that alcohol causes on the 5 HT is by increasing its serotonin release in the nervous system. Studies have shown that after a single drink, there has been increase in concentrations of serotonin in the individual urine and blood. This 5 HT increase indicates that more 5 HT's were released at the serotonergic synapses, thus increasing 5 HT's influence on the output behavior such as emotion, mood and thinking.

In the similar way, alcohol also works to increase the activity and effectiveness of GABA. Since GABA is an inhibitory neurotransmitter, alcohol increases its ability to inhibit. "When alcohol is introduced into this system, its immediate (i.e. acute) effect is to add to (i.e.potentiate) the inhibition caused by the GABAconsequently, neurons receiving messages through GABA are even more inhibited by this transmitter than usual when alcohol is present in the brain." (3). And because GABA neurons are located not in one specific part of the brain, the presence of alcohol inhibits many activities within the brain, influencing behavioral output.

As stated before, the role of Dopamine in output behavior is associated with positive reinforcement. When alcohol is inputted inside the brain, it increases the Dopamine concentrations in reward centers of the brain. These increases of concentration induce the individual to think and behave as if drinking more is okay. This then "ultimately raises the 'set point' for alcohol intake, i.e., the amount it takes to make an alcoholic feel 'normal'" and explains high tolerance levels of frequent drinkers. (4).

Alcohol not only effects the neurotransmitters individually, but also influences the interactions of these three neurotransmitters when working together. For example, 5 HT may interact with neurons that secrete GABA. If alcohol is present, the alcohol influenced 5 HT may effect the actions of GABA neurons in areas involving behavioral output such as the hippocampal formation, where cognitive decisions are made. Similarity, alcohol influenced 5 HT works to stimulate more dopamine production and thus more extreme behavioral outputs.

The exact effect of alcohol's molecules on these neurotransmitters is still under study. The overall behavior output caused by an increase in activity of neurotransmitters is known to be caused by alcohol, but the exact methods of how it is done on a more molecular level is under research. A classmate of mine stated in a weekly forum that "every emotion [that] we feel and every thought [that] we have is due to what's happening inside our brain at the molecular level. [I believe that] the mind/brain/spirit/soul is all the same thingwe think the things we think, do the things we do, and feel the things we feel because of some reactions going on in our brains. And what are those 'reactions' exactly? I don't know." (5). There are many 'reactions' that occurs in our brain which produce behavior. Alcohol is one example of them.

WWW Sources

2)Serotonin's Role in Alcohol's Effects on the Brain

3) Neurochemical Mechanisms Underlying Alcohol Withdrawal

4)Media Awareness Project, maintains an extensive Drugnews Index of drug-related news clippings

5)Neurobiology and Behavior


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