You can thank a little region of your brain called the lateral habenula for all the decisions you make throughout the day.
Researchers from the University of British Columbia found that this brain region -- which has been linked in past studies to avoidance behaviors and depression -- could also have a role in decision-making.
For the study, published in the journal Nature Neuroscience, researchers had rats choose between large and small rewards, which were coupled with costs (waiting a short amount of time or a long amount of time to receive the food). The rats always chose the larger rewards when costs were low, and always chose the smaller rewards when the costs were high.
But then, researchers manipulated the rats' brains to turn off the lateral habenula. When they did this, the rats started making choices based not on rationality, but at random.
"These findings reveal a previously uncharacterized role for the LHb [lateral habenula] in reward-related processing, suggesting that it is critical for promoting choice biases during evaluation of the subjective costs and relative benefits associated with different actions," the researchers wrote in the study.
"Disruption of LHb signal outflow rendered rats unable to display any sort of preference toward larger, costly rewards or smaller, cheaper ones," they wrote. "Instead, the rats behaved as if they had no idea which option might be better for them, defaulting to an inherently unbiased and random pattern of choice, but only when the relative value of the larger reward was tainted by some sort of cost (uncertainty or delays)."
The findings suggest that this brain region plays an important role in helping a person properly weigh costs and benefits in the face of ambiguous decisions, researchers said.