Light gates hormonal modulation of threat avoidance in female mice

Animals must constantly calibrate the costs and benefits of exploration of an environment based on expectations of danger. These decisions are strongly shaped by past experience of perceived threats within that environment and by internal state, which is strongly modulated by circulating gonadal hormones. Although the circuits underlying threat detection are relatively well characterized, how sex hormones shape the long-term behavioral consequences of prior threat experience, and whether this differs across sexes, remains unknown. Here, we show that female mice, like males, exhibit robust long-term threat avoidance (LTTA), avoiding a location where they previously experienced a single visual threat. However, we find that in females this behavior shows strong modulation by the estrous cycle. Surprisingly, we find that though male and female LTTA is driven through glutamate release by the melanopsin-projecting intrinsically photosensitive retinal ganglion cells (ipRGCs) in the thalamic perihabenular nucleus, disruption of this circuit drives completely opposing effects on male versus female LTTA. Moreover, hormonal modulation of LTTA in females requires functional ipRGC input. Thus, despite similar circuit architecture and behavioral outcomes, the individual components of the LTTA circuit play opposing roles in shaping this behavior in males and females, and female LTTA is further tuned by hormonal status.