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Prefrontal cortex regulates cognitive effort during explore/exploit conflict.

Poster Session E - Monday, March 9, 2026, 2:30 – 4:30 pm PDT, Fairview/Kitsilano Ballroom

Paul Cunningham¹ (), Seth Koenig², R. Becket Ebitz³, David Darrow⁴, Alexander Herman⁵; ¹University of Minnesota, ²Université de Montréal, Départment de Neurosciences

The explore/exploit dilemma involves conflict between acquiring reward vs. information and is critical for adaptive behavior. Resolving this conflict is thought to require cognitive effort to override the desire for reward and instead gather information. The prefrontal cortex (PFC) deploys cognitive resources during response conflict and is active during exploration. Thus, we hypothesized that PFC resolves the explore/exploit dilemma by recruiting cognitive resources during heightened information-reward conflict. However, the difficulty of deriving a validated neural measure of cognitive-effort and quantifying reward-information conflict has hampered efforts to test this hypothesis. To this end, we identified a neural readout of cognitive-effort in epilepsy patients with intracranial recordings performing n-back, a task that parametrically stresses cognitive resources. A low-dimensional subspace within PFC high-frequency activity (HFA) predicted the amount of cognitive effort engaged in n-back. Patients also made explore/exploit decisions in a 3-arm restless bandit. PFC cognitive resource deployment in explore/exploit was assessed by projecting HFA measured during bandit onto the cognitive-effort subspace using the same PFC contacts that derived that subspace in n-back. A Volatile Kalman Filter (VKF) was used to estimate reward value and uncertainty across trials, thereby quantifying which options were most rewarding vs. most uncertain to identify trials with high reward-information conflict. High-conflict trials were those in which the most rewarding and uncertain options were different. The PFC cognitive-effort subspace was elevated during high conflict trials, especially when uncertainty resolution was chosen over exploitation. These findings discovered a low-dimensional readout of cognitive-effort within PFC that activates specifically during directed exploration.

Topic Area: THINKING: Decision making