Fluctuations in Brain Activity Could Influence Whether we Take a Risk or Play it Safe

Changes in our brain activity might lead us to make or avoid risky decisions, a study suggests.

Humans have "surprisingly" inconsistent behavior, according to the authors of a paper published in the journal PNAS. So the team set out to understand whether fluctuations in our brains might be partly to blame.

By studying people's brains, the scientists found changes in the part of the brain responsible for releasing the neurotransmitter dopamine appears to influence whether we pick the risky or safe option in any given scenario. Dopamine is linked to risky behavior.

The study involved 43 participants who were instructed to pick between a safe option, which would enable them to gain a small amount of money, versus a risky choice, where they could gain more cash but would get nothing if they lost.

Participants completed the task while in an MRI scanner, so the researchers could watch for changes in the part of the brain packed with the most dopamine neurons: the dopaminergic midbrain. Researchers watched to see if there was a spike or drop in activity in the dopaminergic midbrain while the participants were idle, and then instructed them to decide on whether to take the gamble.

When the dopaminergic midbrain was bustling with activity, the participants were more likely to take a risk, compared with times of low activity, the team found.

Tobias Hauser, co-author of the study at UCL Queen Square Institute of Neurology, told Newsweek: "We wondered why humans are so consistently inconsistent when making decisions.

"What we know from previous brain research is that the brain is never 'at
rest.' Even when in its idle state, brain activity constantly goes up and down. We thus conjectured that maybe these brain fluctuations influence how we make decisions, which is indeed what we found.

Hauser argued the study demonstrates "that it matters in which brain state we
are currently in when we make a decision. Our findings thus highlight that even if we think we act totally rationally, we often act in inconsistent ways and are driven by our brain's current state."

The findings hit back at the idea that risk-taking is a personality trait partly influenced by genetics, they wrote. Instead, it could also rely on internal fluctuations.

Robb Rutledge, senior author of the study at UCL Queen Square Institute of Neurology, commented in a statement: "Our brains may have evolved to have spontaneous fluctuations in a key brain area for decision making because it makes us more unpredictable and better able to cope with a changing world."

Co-lead author Ph.D. student Benjamin Chew of the UCL Queen Square Institute of Neurology, commented: "Our findings underscore the importance of taking time when making important decisions, as you might make a different decision if you just wait a few minutes."

Last year, a study published in the journal Neuron linked risk-taking to brain structure in the amygdala: a set of neurons that play a role in the processing of emotions.

This article has been updated with comment from Tobias Hauser.