Periaqueductal gray activates antipredatory neural responses in the amygdala of foraging rats

Abstract

Pavlovian fear conditioning studies propose that the interaction between the dorsal periaqueductal gray (dPAG) and basolateral amygdala (BLA) functions as a prediction error mechanism for fear memory formation. However, their roles in responding to naturalistic predatory threats, where predictive cues are ambiguous and do not afford reiterative trial-and-error learning, remain unexplored. We conducted single-unit recordings in rats engaged in an ‘approach food-avoid predator’ behavior, characterizing dPAG and BLA neurons responsive to a looming robot predator. Opto-stimulation of dPAG induced fleeing and increased BLA activity. Notably, BLA neurons activated by dPAG stimulation displayed an immediate response to the robot and heightened synchronous activity compared to non-responsive BLA neurons. Furthermore, anterograde and retrograde tracer injections into the dPAG and BLA, respectively, indicate that the paraventricular nucleus of the thalamus (PVT) may mediate dPAG-to-BLA neurotransmission. Our findings suggest that dPAG and BLA interactions, potentially via the PVT, underlie an innate antipredatory defensive mechanism.