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There are so many decisions to make - about 35,000 for an average adult each day. Surely some of these are logically thought out but most are made at an instinctual level, using a sense of emotion or vaguely defined likes and dislikes.
Decisions, decisions... Dopamine? 021512 NEWS 2 For the Capital City Weekly There are so many decisions to make - about 35,000 for an average adult each day. Surely some of these are logically thought out but most are made at an instinctual level, using a sense of emotion or vaguely defined likes and dislikes.
Wednesday, February 15, 2012

Story last updated at 2/15/2012 - 12:06 pm

Decisions, decisions... Dopamine?

There are so many decisions to make - about 35,000 for an average adult each day. Surely some of these are logically thought out but most are made at an instinctual level, using a sense of emotion or vaguely defined likes and dislikes. Varying levels of physical, emotional and experiential resources are required to carry out each choice. Because some choices could put us in danger, we anticipate their outcomes, weighing their potential results. Obviously, we want to maximize the benefit and minimize the cost of each decision. Rewards are often associated with pleasure, and the focus of this article is to explore ways the chemical and neurotransmitter dopamine help guide and influence decision-making processes by transmitting signals associated with pleasure.

Dopamine is biosynthesized from the essential amino acid tyrosine, and is one of the most widely studied neurotransmitters. A typical dopamine stimulation cycle is as follows: A pleasurable experience - or anticipation of such an experience - prompts neurons to release dopamine, which stimulated dopamine receptors on near-by neurons. After the stimulus ceases and/or dopamine stores are depleted, extracellular dopamine is recycled in a process called reuptake. This allows neurons to return to a resting activity level.

The dopamine excitation cycle can be hijacked by certain drugs, including cocaine, which inhibit the dopamine reuptake mechanism and cause prolonged periods of stimulation. Conversely, decreased dopamine levels following stimulation characterize some kinds of depression. This is consistent with one of the symptoms of depression: those things that used to bring one pleasure no longer continue to do so. In fact, the natural anti-depressant St. John's Wart works partly by inhibiting dopamine reuptake. Though dopamine is involved in a multitude of interesting physiological and psychological processes, let's return to the role of dopamine in decision-making.

Imagine you're engaging in a pleasurable activity, let's say dancing. For you, this activity would release dopamine. But you can also get a rush of dopamine from watching others dance, looking at pictures of dance poses, or even fantasizing about a particular movement sequence. The fantasizing-dopamine connection helps explain how we make decisions when the outcomes are unknown. Say there are two hypothetical scenarios, A and B. We can imagine (fantasize) ourselves doing scenario A, measure the pleasure response (dopamine release) and then compare this to the anticipated response from scenario B. If we were deciding purely on our pleasure responses, then the scenario with the maximum dopamine release would be our choice. Typically, however, logic - as well as pleasure - is factored into the decision-making process. Otherwise, we would skip "boring" (low dopamine) but necessary tasks like work or cleaning.

A study published in the Journal of Neuroscience investigated the role of dopamine in decisions between "smaller-sooner" rewards and bigger rewards that require patience and/or perseverance. In this study participants were given either a sugar pill placebo or a pill containing L-DOPA. L-DOPA is a precursor of dopamine which can cross the blood-brain barrier and then be bio-converted into active dopamine. The subjects were then allowed to decide between "smaller-sooner" and delayed gratification choices (i.e. receiving $30 in two weeks or waiting six months to receive $100). Participants who had received L-DOPA made a higher percentage of "shorter-sooner" choices, reflecting impulsive decisions. Similarly, higher-than-normal dopamine levels often accompany Attention Deficit Hyperactivity Disorder (ADHD). Thus, it is not surprising that impulsive tendencies are one symptom of ADHD.

One of the most famed aspects of dopamine is the role it plays in relationships and attraction. Brain imaging studies have shown that just looking at a photograph of a loved one "lights up" the area of the brain that produces dopamine. This connection between high dopamine levels and impulsiveness could help explain the phenomenon of not making the best rational decisions when under the influence of infatuation. In fact, the brain chemistry of people in the so-called infatuation stage of love resembles that of people with an obsessive-compulsive disorder, or a person under the influence of narcotics.

Fantasizing about potential outcomes allows us to virtually experiment with perceived pleasure and act accordingly ... or not. If I ever cringe while thinking about some decisions I made while under the influence of attraction, or while day-dreaming, I try and remember that my brain physiologically-affected. Overall, however, I would like to welcome more dopamine into my life. It is reported that consuming tyrosine-rich foods (most proteins, almonds, avocados, bananas and pumpkin seeds are some), may help increase dopamine levels, by providing the key chemical building block to dopamine production. Activities that bring pleasure are another way boost dopamine - choose wisely, though, because not all things that bring pleasure bring long-term benefits.

Jasmina Allen holds degrees in Chemistry and Biology, and currently lives in Juneau.