A CU-Boulder team studying Parkinson's disease patients found strong evidence that dopamine in the brain plays a key role in how people implicitly learn to make choices that lead to good outcomes, while avoiding bad ones.
The finding could help researchers understand more about how the brain works and could lead to a better understanding and treatment of brain disorders like schizophrenia, according to CU-Boulder psychology graduate student Michael Frank, who led the study.
A paper on the subject by Frank, CU-Boulder psychology Associate Professor Randall O'Reilly and Lauren Seeberger of the Colorado Neurological Institute's Movement Disorders Center appears in the Nov. 5 issue of Science Express, an online version of Science magazine.
Often people will get a "gut feeling" that allows them to make a choice depending on how often it was associated with positive outcomes in the past. But people with Parkinson's disease often have difficulty making these kinds of choices, Frank said.
To understand why, they developed a computer model of the effects of Parkinson's disease and the medications used to treat it in the brain. From this model they predicted that Parkinson's patients would differ in their decision making depending on whether or not they were taking their medication, which they confirmed in a subsequent study.
They found that patients on their medication were overly influenced by positive outcomes, while those who were off their medication were more influenced by negative outcomes, according to Frank.
"Because Parkinson's disease is caused by lower levels of the brain chemical dopamine, and the medications increase concentrations of this chemical, these results provide strong evidence that dop