Modulation of Innate Defensive Responses by Locus Coeruleus-Superior Colliculus Circuit.

Among key survival circuits, defensive response circuits are one of the most intensively studied. A consensus is emerging that multiple, independent circuitries are involved in different conditioned and unconditioned defensive responses. Investigating these well-conserved defensive responses would help us to decipher the basic working mechanism of the brain at a circuitry level and thus shed light on new diagnoses and treatments for neural diseases and disorders. We showed that the visually evoked innate defensive response was modulated by a locus coeruleus-superior colliculus (LC-SC) projection. Our work demonstrates that as conserved and instinctive as the survival circuits are, they are flexible and subject to fine-tuned modulation by experience or internal states of the animals. Here, we provide more data to further discuss the possible downstream mechanisms of the LC-SC pathway for this important modulation of the defensive response, the wide range of flight latency between individual flight responses, and the interpretations of our data with additional statistical analysis.