London: Some people who receive deep brain stimulation for Parkinson’s disease are impulsive, leading them to make quick and often, bad, decisions.
Now, a new study has explained why and shown how under normal circumstances key parts of the brain collaborate to devote time to reflect on tough choices.
Michael Frank, professor of cognitive, linguistic, and psychological sciences at Brown University, studied the impulsive behavior of Parkinson’s patients when he was at the University of Arizona several years ago.
His goal was to model the brain’s decision-making mechanics. He had begun working with Parkinson’s patients because DBS, a treatment that suppresses their tremor symptoms, delivers pulses of electrical current to the subthalamic nucleus (STN), a part of the brain that Frank hypothesized had an important role in decisions.
He wondered if the STN pulls the brakes on impulses, giving the medial prefrontal cortex (mPFC) time to think.
“We didn’t have any direct evidence of that,” said Frank, who is affiliated with the Brown Institute for Brain Science.
but the researchers’ measurements from two experiments and analysis with a computer model supported the theory that when the mPFC is faced with a tough decision, it recruits the STN to ward off more impulsive urges coming from the striatum, a third part of the brain. That allows it time to make its decision.