A study has shown that variations of three different genes, known as single-nucleotide polymorphisms, in the brain may help predict a person's tendency to make certain choices.
A collaborative study conducted by researchers from Brown University and the University of Arizona has tested DNA samples from saliva in conjunction with computerized cognitive tests, and found that the certain gene variations could be connected to certain choices, focusing on decisions that previously produced good outcomes, avoiding negative outcomes, or trying unfamiliar things even though an outcome is uncertain.
"In some cases, single genes can have surprisingly strong influences on particular aspects of behavior," Nature magazine quoted Michael J. Frank, assistant professor of cognitive and linguistic science, psychology, and psychiatry and human behavior, as saying.
The research team examined the effects of three genes that control aspects of dopamine function in the brain, while participants performed a computerized decision-making task.
Dopamine is a neurotransmitter that helps keep the central nervous symptom functioning. Its levels fluctuate as the brain feels motivated or rewarded.
The researchers observed that varations in two of the genes, DARPP-32 and DRD2, independently predicted the degree to which people responded to outcomes that were better or worse than expected, by reinforcing approach and avoidance type behaviors.
They say that these genes affect dopamine processes in the basal ganglia portion of the brain.
According to Frank, this is important for "simple reinforcement of learning processes that you might not even be aware of."
The researchers also studied exploratory decision-making, the choices people make when they are in "uncharted territory", and found that variations in a third gene, COMT, predicted the extent to which people explored decisions, when they were uncertain whether the decisions might produce better outcomes.
The researchers note that COMT affects dopamine levels in the prefrontal cortex, known as an executive center of the brain.
Frank said the findings could have some interesting implications.
"We cannot say on the basis of one or two studies, but if a student isn't doing well in a particular learning environment, [a gene study could show that the student] may be well-suited to a particular teaching style," he said.
The researchers say that the significance of their findings lies in the fact that they may help shape future treatments for conditions like Parkinson's disease, which involves dopamine loss.
"Medications that increase dopamine stimulation can help treat debilitating aspects of the disease but in some patients the meds can induce pathological gambling and impulsivity," Frank said.
He further said that genetic factors involved in influencing motivational processes in the brain may prove helpful in detecting patients who would be negatively impacted by particular medications.
A research article describing the study has been published in the journal Nature Neuroscience.