Dual regulatory mechanisms of the ZI-LHb circuit in SPS&S model mice: dissociable control of aversion and anxiety through distinct downstream targets.

Post-traumatic stress disorder (PTSD) involves maladaptive aversion processing and anxiety disorders; however, the correlation between these components and their underlying neural circuit mechanisms remains unclear. The single prolonged stress and shock (SPS&S) model reliably induced PTSD-related aversive behaviors in mice through functional reorganization of the zona incerta (ZI)→lateral habenula (LHb) neural pathway. The ZI primarily projected to the lateral subregion of the LHb (LHbL) and consisted predominantly of GABAergic neurons. During the SPS&S expression phase, mice exhibit weakened ZI-LHb connectivity, accompanied by reduced miniature inhibitory postsynaptic current (mIPSC) frequency in ZI-targeted postsynaptic LHb neurons. Circuit-specific suppression of ZI→LHb neurons in naive mice recapitulated PTSD-related symptoms. Compared to control mice, ‌the‌ presynaptic and postsynaptic neurons in the ZI-LHb pathway of SPS&S expression mice show weakened and amplified activation, respectively, during aversive stimulus processing. During the SPS&S acquisition and expression phase, chemogenetic activation of this pathway rescued anxiety-like behaviors and aversion responses without affecting depression. Downstream tracing reveals divergent functions: the ZI-LHb-ventral tegmental area (VTA) pathway mediates aversion, while ZI-LHb-rostromedial tegmental nucleus (RMTg) primarily regulates anxiety manifestations. Our findings establish the ZI-LHb circuit as a dual-control hub in PTSD-related phenotype, offering new therapeutic targets.