Some decisions arouse far more anxiety than others. Among the most anxiety-provoking are those that involve options with both positive and negative elements, such choosing to take a higher-paying job in a city far from family and friends, versus choosing to stay put with less pay.
MIT researchers have now identified a neural circuit that appears to underlie decision-making in this type of situation, which is known as approach-avoidance conflict.
Making hard choices
When humans are forced to make these kinds of cost-benefit decisions, they usually experience anxiety, which influences the choices they make. "This type of task is potentially very relevant to anxiety disorders," they said. "If we could learn more about this circuitry, maybe we could help people with those disorders."
Using optogenetics, which allowed them to turn cortical input to the striosomes on or off by shining light on the cortical cells, the researchers found that the circuit connecting the cortex to the striosomes plays a causal role in influencing decisions in the approach-avoidance task, but none at all in other types of decision-making.
When the researchers shut off input to the striosomes from the cortex, they found that the rats began choosing the high-risk, high-reward option as much as 20 percent more often than they had previously chosen it. If the researchers stimulated input to the striosomes, the rats began choosing the high-cost, high-reward option less often.
The findings suggest that the striatum, and the striosomes in particular, may act as a gatekeeper that absorbs sensory and emotional information coming from the cortex and integrates it to produce a decision on how to react, the researchers say.