By COLLEEN CREAMER
for The Nashville City Paper
Vanderbilt University researchers have found a part of the brain that monitors the consequences of actions more than the actions themselves, a finding that could improve understanding of impulsive behavior.
The study, published this month in Science magazine, could help doctors understand and treat disorders such as schizophrenia, obsessive-compulsive disorder and Attention Deficit Hyperactivity Disorder as well as provide a better understanding of what is now broadly called “poor impulse control,” considered by some scientists to be the root of a certain kind of criminal behavior.
The study shows that the decision-making process in the brain may be more concerned about the consequences of an action than how hard the action is to produce. The part of the brain in question is the anterior cingulate cortex (ACC). Researchers found that the ACC responds to discrepancies between a person’s intentions and what actually happens when actions are performed. The outcome is the latest in a series of experiments that may be at the root of understanding how the brain’s “executive function” monitors its own performance so that it can adjust behavior.
Jeffrey Schall, Ingram Professor of Neuroscience and director of Vanderbilt’s Center for Integrative and Cognitive Neuroscience, directed the study with doctoral student Shigehiko Ito, post-doctoral fellow Veit Stuphorn, and Joshua Brown, a research associate at Washington University.
“The basic idea is you are asked to do something. In our case it was move the eyes, but it could be press a button or say a word,” Schall said. “You do it and do it and sometimes you are told to stop. You are correct if you withhold the movement. So it is a task that is designed exactly to study the control of actions.”
Using Macaque monkeys and a reward system, Schall and colleagues required the monkeys to inhibit a movement after their brains had begun preparing for it. The researchers successfully identified neurons that signaled discrepancies or errors but identified no neuron that signaled what the brain meant to do.
Brown said that the end result is what drives the intention.
“The broad question is, ‘How does the brain monitor and control intentional actions.’ Our research indicates that it does so by monitoring the consequences of such actions, not the actions themselves,” Brown said.
One theory suggests the brain is sensitive to the conflict that comes from when a task is too difficult to perform without making errors. Some people may be more sensitive than other to this conflict and would, therefore, have an advantage in the decision-making process.
“An error is hard for the brain to register, because it is the difference between what you did and what you meant to do,” Schall said.
