Are you a bit of a gambler, or do you tend to be more cautious? As it turns out, the degree to which we are a risk taker appears to be strongly dependent on a neural connection between two parts of our brain. As the study – published in the journal Neuron – reveals, the better this connection is, the less likely we are to take a gamble, at least with our money.
Two brain regions, the anterior insula and the nucleus accumbens, have long been associated with risk and reward. A wide range of behaviors, including cravings for cigarettes, sexually-driven actions, and decision making have all been shown to be partly determined by the anterior insular. In addition, it was shown in rhesus monkeys to be strongly connected to the amygdala, the region of the brain that regulates and controls fear, as well as risk, reward, and to some extent aggression.
The nucleus accumbens also plays a huge role in the brain’s reward system, producing pleasant neurological stimulations for behaviors that are rewarding in some way. These behaviors can include drug use, sex, exercise, and gambling.
Previous neuroimaging studies, primarily using functional magnetic resonance imaging (fMRI) to track the flow of blood and oxygen within the brain, have looked at these two brain regions in detail. Researchers have shown that increased activity in the nucleus accumbens predicts that a risky choice is about to be made; conversely, activity in the anterior insula predicts risk-averse choices.
This new team of researchers, led by Brian Knutson, an associate professor of psychology at Stanford University, hoped to find out how powerful the connection between these two opposing brain regions actually is. In order to accomplish this, a modified version of MRI scanning – “diffusion-weighted” (DW) MRI – was employed. By tracking the movement of mainly water molecules, and how they interact with various obstacles, researchers can use this technique to reveal microscopic details about neurological architecture.
Each participant in the study was given $10 that they could gamble, or keep, in a series of simple gambling games with varying odds. Any money they had at the end of the experiment, they were allowed to keep. Before each gamble was made, their brain was imaged using DW MRI.
The connection between the anterior insula and the nucleus accumbens (red) shown imaged within the brain. Leong et al./Neuron
Regardless of the type of player, the scans revealed that the nucleus accumbens lights up when a big risk is about to be taken, whilst the anterior insula remains quiet. “We could predict the person's upcoming bet based on the balance of activity in these regions,” said Knutson in a statement.
They also showed that, for the first time in humans, the two regions were directly connected. Most significantly, however, they noted that the most risk-averse players were the ones with the strongest connection between both the nucleus accumbens and the anterior insula. The risk-taking nucleus accumbens region remained far quieter in the brains of those with this strong connection, even when a big risk was about to be taken by the associated player.
This implies that the risk-averse anterior insula, along with a strong connection, acts as a tempering feature to the nucleus accumbens. Although it will be some time before any neurological, surgical interventions can be made for those with gambling problems, this finding represents a stepping stone.
“Now we can start asking interesting questions about impulse control and gambling,” Knutson added. “For example, does the connection change over the course of therapy?”