Cortical representations of affective pain shape empathic fear in male mice

Affect sharing, the ability to vicariously feel others' emotions, constitutes the primary component of empathy. However, the neural basis for encoding others' distress and representing shared affective experiences remains poorly understood. Here, using miniature endoscopic calcium imaging, we identify distinct and dynamic neural ensembles in the anterior cingulate cortex (ACC) that encode observational fear across both excitatory and inhibitory neurons in male mice. Notably, we discover that the population dynamics encoding vicarious freezing information are conserved in ACC pyramidal neurons and are specifically represented by affective, rather than sensory, responses to direct pain experience. Furthermore, using circuit-specific imaging and optogenetic manipulations, we demonstrate that distinct populations of ACC neurons projecting to the periaqueductal gray (PAG), but not to the basolateral amygdala (BLA), selectively convey affective pain information and regulate observational fear. Taken together, our findings highlight the critical role of ACC neural representations in shaping empathic freezing through the encoding of affective pain.