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Brain

Dopamine and immediacy

Daniel BuenoA timely variation in a gene that helps regulate the amount of dopamine in the brain seems to influence a specific aspect of impulsivity related to decision-making.  This gene stores the recipe of the enzyme that degrades dopamine and is found in two versions:  one generates a more active enzyme and the other a less effective enzyme.  By analyzing the performance of healthy individuals on two neuropsychological tests, researchers at the Federal University of Minas Gerais (UFMG) verified that those who have two copies of the allele that manufactures the less active enzyme performed worse on a task that evaluates the long-term consequences of decision-making – what is known as decision-making impulsivity.  On one of the tests, Leandro Malloy-Diniz subjected 192 study participants to a virtual game in which they won or lost money by choosing playing cards from four different piles.  Before beginning the game, the researcher told them that some of the piles were more profitable than others.  The cards in certain piles yielded bigger profits, but they also generated bigger losses, while those from the other piles generated more modest winnings and fewer losses.  The people who produced the less efficient enzyme – and had higher levels of dopamine – performed worse on this task, but not on another that measured the capacity to pay attention during an activity and the ability to inhibit a particular motor response (PLoS One, September 10, 2013).  “These results reinforce the hypothesis that different aspects of impulsivity are independent and derived from different neurobiological bases,” the researchers write.

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