Prefrontal regulation of exploratory behavior: complementary functions of medial prefrontal and orbitofrontal cortices in a competitive choice task
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Date
2025
Authors
Livingstone, Benjamin A. S.
University of Lethbridge. Faculty of Arts and Science
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Publisher
Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience
Abstract
Adaptive decision-making requires balancing exploration of uncertain options with exploitation of known rewards. This thesis investigates how the rat medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC) contribute to this trade-off during a competitive binary choice task (BCT), where stereotyped responses are punished and stochastic responding is rewarded. Male Long-Evans rats received excitotoxic lesions to the mPFC, OFC, or sham surgery, then performed the BCT across stable and volatile conditions. Behavior was analyzed using generalized linear mixed models to assess trial-level changes in extraneous feeder sampling (EFS), a non-rewarded exploratory action.
Lesions did not impair overall task engagement. However, OFC lesions caused a persistent elevation in EFS during the first post-operative session, consistent with impaired suppression of valueless behavior. In contrast, mPFC lesions led to an accelerated within-session decline in EFS, suggesting a deficit in sustaining exploratory strategies over time. Under environmental uncertainty, when the physical configuration of the task changed mid-session, both lesion groups showed a blunted increase in EFS and failed to reduce exploration across days.
These findings reveal a dissociation in stable environments: the OFC is critical for value-based suppression of exploration, while the mPFC supports its flexible maintenance. Under uncertainty, both regions are necessary for adaptive exploration, suggesting that they converge within a broader prefrontal network recruited during volatile conditions. This work clarifies the distinct and overlapping roles of the mPFC and OFC in regulating exploration and offers insight into prefrontal contributions to flexible decision-making.
Description
This thesis covers an experiment where rats underwent neurotoxic lesions to either the medial prefrontal cortex or the orbitofrontal cortex. Rats were then ran on a competitive decision-making task, where the rats exhibited exploratory behaviours. Exploratory behavious was compared between lesion groups.
Keywords
behaviour , Long-Evans rats , medial prefrontal cortex , orbitofrontal cortex , lesion , exploration