Intercalated amygdala dysfunction drives avoidance extinction deficits in the Sapap3 mouse model of obsessive-compulsive disorder.

Background: The avoidance of aversive stimuli through negative reinforcement learning is critical for survival in real-world environments, which demand dynamic responding to both positive and negative stimuli that often conflict with each other. Individuals with obsessive-compulsive disorder (OCD) commonly exhibit impaired negative reinforcement and extinction, perhaps involving deficits in amygdala functioning. An amygdala subregion of particular interest is the intercalated nuclei of the amygdala (ITC) which has been linked to negative reinforcement and extinction, with distinct clusters mediating separate aspects of behavior. This study focuses on the dorsal ITC cluster (ITC_d) and its role in negative reinforcement during a complex behavior that models real-world dynamic decision making.

Methods: We investigated the impact of ITC_d function on negative reinforcement and extinction by applying fiber photometry measurement of GCamp6f signals and optogenetic manipulations during a platform-mediated avoidance task in a mouse model of OCD-like behavior: the Sapap3-null mouse.

Results: We find impaired neural activity in the ITC_d of male and female Sapap3-null mice to the encoding of negative stimuli during platform-mediated avoidance. Sapap3-null mice also exhibit deficits in extinction of avoidant behavior, which is modulated by ITC_d neural activity.

Conclusions: Sapap3-null mice fail to extinguish avoidant behavior in platform-mediated avoidance, due to heightened ITC_d activity. This deficit can be rescued by optogenetically inhibiting ITC_d during extinction. Together, our results provide insight into the neural mechanisms underpinning negative reinforcement deficits in the context of OCD, emphasizing the necessity of ITC_d in responding to negative stimuli in complex environments.