PREFRONTAL CORRELATES OF A SOCIAL LEARNING STRATEGY DURING JOINT DECISION-MAKING IN MICE

Social animals observe others to guide their behavior and strategically choose when and from whom to learn. Although prefrontal cortical areas encode the actions and attributes of others, how these representations adapt to varying task demands and decisional uncertainty remains unclear. We designed a behavioral paradigm where pairs of mice, separated by a transparent divider, jointly perform a visually guided, two-alternative forced-choice task. Trial-by-trial, we independently varied visual cue contrast for each mouse to create different levels of perceptual uncertainty between the pair. We observed that mice facing low-contrast stimuli reliably copied the decisions of partners with high-contrast cues, a stereotyped behavior consistent with a “copy when uncertain” strategy. This reliance on social information was abolished when the partner was replaced by a mechanical slider, confirming the social nature of the computation. Whole-brain c-Fos mapping revealed increased medial prefrontal cortex (mPFC) activation in mice performing the task jointly compared to those performing it solo. Enhanced activity in regions anatomically and functionally connected to the mPFC suggests it acts as a hub for integrating private sensory evidence with social information. Large-scale electrophysiological recordings identified single prefrontal neurons with ramping activity that preceded stimulus presentation. This activity was boosted by stimulus onset in a contrast-dependent manner and was higher in trials where mice copied their partner compared to behaviorally-matched solo trials. We demonstrate that mice actively monitor conspecifics to guide their own decisions under perceptual uncertainty and suggest that social evidence is integrated with visual evidence into a decision variable in mPFC.