Brain's decision-making centre identified

Researchers have identified the decision-making centre of brain that helps people decide whether to have the second glass of alcohol.

Studying how cost-benefit decisions are made when choosing to consume alcohol, researchers identified distinct profiles of brain activity that are present when making these decisions.

"We were interested in understanding how the brain makes decisions about drinking alcohol. Particularly, we wanted to clarify how the brain weighs the pros and cons of drinking," said James MacKillopp from the University of Georgia.

The study combined functional magnetic resonance imaging and a bar laboratory alcohol procedure to see how the cost of alcohol affected people's preferences.

The study group included 24 men, aged 21-31, who were heavy drinkers. Participants were given a USD 15 bar tab and then were asked to make decisions in the functional magnetic resonance imaging (fMRI) scanner about how many drinks they would choose at varying prices, from very low to very high.

Their choices translated into real drinks, at most eight that they received in the bar immediately after the scan. Any money not spent on drinks was theirs to keep.

The study applied a neuroeconomic approach, which integrates concepts and methods from psychology, economics and cognitive neuroscience to understand how the brain makes decisions.

Participants' cost-benefit decisions were categorised into those in which drinking was perceived to have all benefit and no cost, to have both benefits and costs, and to have all costs and no benefits.

In doing so, MacKillop could dissect the neural mechanisms responsible for different types of cost-benefit decision-making.

"We tried to span several levels of analysis, to think about clinical questions, like why do people choose to drink or not drink alcohol, and then unpack those choices into the underlying units of the brain that are involved," he said.

When participants decided to drink in general, activation was seen in several areas of the cerebral cortex, such as the prefrontal and parietal cortices.

However, when the decision to drink was affected by the cost of alcohol, activation involved frontostriatal regions, which are important for the interplay between deliberation and reward value, suggesting suppression resulting from greater cognitive load.

This is the first study of its kind to examine cost-benefit decision-making for alcohol and was the first to apply a framework from economics, called demand curve analysis, to understanding cost-benefit decision making.

The study appears in the journal Neuropsychopharmacology.