FROM FEAR TO ACTION: BASOLATERAL AMYGDALA–NUCLEUS ACCUMBENS CIRCUIT MECHANISMS IN AVOIDANCE LEARNING

Adaptive avoidance requires animals to shift from passive defensive responses, such as freezing, to active behaviors that prevent an aversive outcome. However, the neural mechanisms supporting this transition remain poorly understood. In this study, we investigated the role of the basolateral amygdala–nucleus accumbens pathway in active avoidance learning. Using an active avoidance task in rodents, we examined how neural activity evolves from threat-related cue processing to action initiation and successful avoidance. We combined high-resolution behavioral analysis with fiber photometry and in vivo electrophysiology to record neural dynamics within this pathway across different stages of learning. In parallel, optogenetic manipulations were used to causally test the contribution of this circuit during specific task phases. Our results show that activity within the basolateral amygdala–nucleus accumbens pathway is strongly modulated during avoidance acquisition and reflects the transition from passive defensive responses to goal-directed action. Optogenetic disruption of this pathway selectively impaired avoidance acquisition while sparing the expression of learned avoidance, indicating a critical role in associative learning rather than action execution. Further analyses suggest that motor-related aversive information conveyed through this circuit is necessary for the formation of effective avoidance strategies. Together, these findings identify the basolateral amygdala–nucleus accumbens pathway as a key circuit supporting the selection of active defensive behaviors under threat and provide insight into mechanisms that may contribute to maladaptive avoidance or excessive freezing in anxiety-related disorders.