Regulation of the decision threshold by the locus coeruleus.

A fundamental challenge for decision-making under uncertainty lies in balancing speed and accuracy. Humans and animals solve this problem by adjusting decision thresholds-the criterion that determines how much information is required before committing to a choice. While brain regions associated with this process have been identified, the neural circuits that directly alter decision thresholds remain unknown. Here, we investigate the role of the locus coeruleus (LC) norepinephrine (NE) system in controlling this balance. Through cell-type-specific chemogenetic manipulations, we discovered that LC-NE activation increased decision thresholds. This effect is replicated by administration of the α2-adrenergic receptor (α2-AR) agonist clonidine. Notably, α2-AR activation altered decision threshold specifically, without reproducing other LC-NE activation effects such as promoting task engagement. Together, these results suggest that LC-NE regulates decision thresholds, possibly via downstream α2-ARs.