This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
Biology 202, Spring 2005
First Web Papers
Dopamine is neurotransmitter in the brain that plays vital roles in a variety of different behaviors. The major behaviors dopamine affects are movement, cognition, pleasure, and motivation (1). Dopamine is an essential component of the basal ganglia motor loop, as well as the neurotransmitter responsible for controlling the exchange of information from one brain area to another (1). However, it is the role that dopamine plays in pleasure and motivation that attracts the most neurobiologists attention as well as mine.
In certain areas of the brain when dopamine is released it gives one the feeling of pleasure or satisfaction (1). These feelings of satisfaction become desired, and the person will grow a desire for the satisfaction. To satisfy that desire the person will repeat behaviors that cause the release of dopamine (2). For example food and sex release dopamine (2). That is why people want food even though their body does not need it and why people sometimes need sex. These two behaviors scientifically make sense since the body needs food to survive, and humans need to have sex to allow the race to survive. However, other, less natural behaviors have the same effect on one's dopamine levels, and at times can even be more powerful. Often these behaviors can result in addiction due their effect on dopamine, and that addiction can have negative effects on a person's well-being. Two of such behaviors are
Cocaine is by far the more severe of the two in terms of addiction. Cocaine chemically inhibits the natural dopamine cycle. Normally, after dopamine is released, it is recycled back into a dopamine transmitting neuron. However, cocaine binds to the dopamine, and does not allow it to be recycled. Thus there is a buildup of dopamine, and it floods certain neural areas (3). The flood ends after about 30 minutes, and the person is left yearning to feel as he or she once did (3). That is how the addiction begins. Progressively a tolerance builds up due to the fact that the person is constantly trying to repeat the feeling that he or she had the first time (2). However, the person cannot, because dopamine is also released when something pleasurable yet unexpected occurs (4). After the first time, the person expects the effect, thus less dopamine is released, and the experience is less satisfying. This principal is the foundation of why gambling releases dopamine.
Several studies have been conducted which targeted neural response to rewards. The results were unanimous in the fact that when one performed an action over and over again, and was given a reward randomly, dopamine levels rose. If the reward was given consistently, i.e. every four time the action was performed, the dopamine levels remained constant. Finally, if no reward was given dopamine levels dropped (4). These same random rewards can be seen in gambling. Because the outcome is based on chance, one does not know prior if he or she will win. Therefore, if the person one wins, dopamine levels increase (4). However, unlike cocaine, gambling causes addiction in only 4% of participants. This is due to the fact that Cocaine's chemical input is much more influential on dopamine levels than gambling's behavioral input. Therefore, only people whose dopamine levels are low, become addicted to gambling (5).
This brings up a very interesting topic of discussion. How do some people have lower dopamine levels than others? Is it genetic, environment related, something else, or a combination of factors? One study concluded that pathological gamblers most often experienced traumatizing experiences when they were younger (5). Because most people who become addicted to gambling have low dopamine levels, and also that same group usually has endured a traumatic experience, we have support for the observation that overall dopamine levels can change due to environmental factors. This then supports the observation that both the mind and brain can change to environmental factors. However, another study has observed that a gene related to dopamine is found twice as often in pathological gamblers than non-gamblers (5). This supports the observation that dopamine levels are genetic. Therefore, there are two plausible observations that can be made. Either both genetics and environmental factors effect ones brain anatomy and mind simultaneously, or that environmental factors can affect genes which in turn affect ones brain and mind. Because the observations in the studies show such a strong correlation between pathological gambling, traumatic experiences, and genetic influence, it the later which seems to be the least wrong observation.
Another important question, however more philosophical, is why is risk and reward a trigger for the release of dopamine? As stated earlier, it is scientifically logical that sex and food release dopamine, because they are essential for the sustained life of man. Risk and reward are not, are they? It is my belief that in nature everything happens for a reason; therefore, there must be a scientific explanation for the increase of dopamine levels in result of risk and reward. It seems to me that the human race separates itself from other species on this planet by not only its ability to reason, but its ability to create and innovate. I feel that nature wants humans to create and innovate, and in order to do this a person has to feel satisfaction when one accomplishes an innovation. To accomplish an innovation one has to take risks. It is risky to try to do something that no other being on earth has ever accomplished. Therefore, there must be a reward other than material that one gets when he or she accomplishes the innovation, or that person would not take the risk. The reward is the release of dopamine and the feeling of satisfaction. The problem with this process is that not only can one be satisfied after a major risk and accomplishment, but one can also be satisfied through constant minute risks and accomplishments. Gambling is an example of this.
These feelings of satisfaction that dopamine exhibits are so strong that one can often loses one's ability to reason in order to achieve satisfaction (4). It is then the unconscious that takes over and begins to make certain decisions. The brain develops neural circuits that unconsciously assess reward (4). Because the dopamine plays an active role in these circuits, a person will act in what they think is in their best interest, when in fact the only interest it satisfies is the release of dopamine. This can be exemplified in gambling where one insists on gambling even though he or she knows that the odds are against them (4). This is the case in all casino games, where the games are structured for the house to win. Probability and reason no longer are the most important factors in decision making. The unconscious need for the release of dopamine becomes most important. This supports the observation that the unconscious plays a vital role in decision making.
From this discussion of dopamine and addiction I was able to make some fairly general observations abut the brain. I observed that both a chemical (cocaine) and a behavior (gambling) can have the same effect on the brain. Furthermore, I observed that the brain is affected by both genes and environmental factors, and that most likely the environmental factors affect genes which affect the brain. Also, I was able to observe that dopamine makes humans take risks so that they may achieve greater innovations. And finally it was observable through gambling that the unconscious is constantly making important decisions. It is amazing how one specific topic can generate so many general observations about how the brain, mind, and nature function.
2) The Dopamine Connection
3) Cocaine Abuse and Addiction
4) Hijacking the Brain Circuits with a Nickel Slot Machine
5) Mental and Physical Status of Gamblers: Physiological Findings
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