Cortical regulation of collective social dynamics during environmental challenge.

Animal groups often collectively coordinate their behavior to withstand environmental challenges, yet the neural circuitry underlying such collective social dynamics remains unclear. Here we show that groups of mice self-organize into huddles under cold stress. We quantified the thermoregulatory benefits of huddling using thermal imaging and internal temperature loggers, which revealed that it stabilized core body temperature by increasing thermal contact points and reducing heat loss. We next characterized decision-making processes that govern huddling dynamics and found that mice employed both active (self-initiated) and passive (partner-initiated) strategies to enter or exit a huddle. Microendoscopic calcium imaging revealed that active and passive decisions are encoded in distinct neuronal ensembles within the dorsomedial prefrontal cortex. Chemogenetic silencing of dorsomedial prefrontal cortex activity selectively reduced active decisions in targeted mice but elicited compensatory increases in non-manipulated partners, preserving overall group-level huddle time. These findings uncover a cortical mechanism by which social groups collectively adapt to maintain homeostasis under environmental challenge.