Brain Region Associated with Decision-making Identified

A new study suggests that one of the smallest and oldest parts of the brain in terms of evolution may play a key role in decision-making.

Past research suggests that switching off the lateral habenula, a region of the brain associated with depression and avoidance behaviors, causes rats to make riskier choices with higher rewards.

In a new study published in the journal Nature Neuroscience, University of British Columbia researchers came to a different set of conclusions after training lab rats to choose between a small reward of one food pellet, versus a four-pellet reward distributed sporadically.

Like humans, the rats chose larger rewards when costs, such as the time they had to wait before receiving food, were low, and opted for smaller rewards when risks increased.

Once the scientists turned the lateral habenula off, rather than preferring the riskier option, the rats seemed to lose the ability to form decisions, selecting options randomly.

"These findings clarify the brain processes involved in the important decisions that we make on a daily basis, from choosing between job offers to deciding which house or car to buy," Professor Stan Floresco of UBC's Department of Psychology and Brain Research Centre (BRC) said in a statement. "It also suggests that the scientific community has misunderstood the true functioning of this mysterious, but important, region of the brain."

Beyond decision-making, the study could carry with it significant implications for depression, schizophrenia and stimulant abuse -- all of which are associated with impairments to cost-benefit decision processes and other related behaviors.

"Deep brain stimulation -- which is thought to inactivate the lateral habenula -- has been reported to improve depressive symptoms in humans," Floresco said. "But our findings suggest these improvements may not be because patients feel happier. They may simply no longer care as much about what is making them feel depressed."