External Globus Pallidus Arkypallidal Circuit Dynamics Gate Risk-Taking Behavior

Exploration allows animals to gather information and adapt to changing conditions. Yet, it also exposes them to potential threats, requiring neural systems that weigh uncertainty and regulate behavioral transitions between cautious and exploratory states. These computations are distributed across cortical and subcortical networks, including the basal ganglia, which integrate sensory, motivational, and contextual information to shape action-selection behaviors. Within this circuitry, the globus pallidus externa (GPe) occupies a central but underappreciated role. Once viewed as a relay between striatum and downstream nuclei, the GPe is gaining recognition as a dynamic regulator that integrates diverse inputs and exerts bidirectional control over motor and cognitive processes. Here, we examine arkypallidal NPAS1-expressing GPe (GPe^NPAS1) neurons, which form preferential inhibitory projections to the striatal matrix. Chemogenetic manipulations and in vivo calcium measurement reveal that GPe^NPAS1 activity modulates and encodes risk-taking behavior sequences, identifying a circuit mechanism by which the GPe can regulate adaptive decision-making in risky contexts.