Advances in neural circuits of innate fear defense behavior.

Abstract

Fear, a negative emotion triggered by dangerous stimuli, can lead to psychiatric disorders such as phobias, anxiety disorders, and depression. Investigating the neural circuitry underlying congenital fear can offer insights into the pathophysiological mechanisms of related psychiatric conditions. Research on innate fear primarily centers on the response mechanisms to various sensory signals, including olfactory, visual, and auditory stimuli. Different types of fear signal inputs are regulated by distinct neural circuits. The neural circuits of the main and accessory olfactory systems receive and process olfactory stimuli, mediating defensive responses like freezing. Escape behaviors elicited by visual stimuli are primarily regulated through the superior colliculus and hypothalamic projection circuits. And auditory stimuli-induced responses, including escape, are mainly mediated through auditory cortex projection circuits. As for auditory stimuli, they are mainly triggered by the auditory cortical projection circuits, leading to escape and other responses. In this article, we review the research progress on the neural circuits of innate fear defensive behaviors in animals from different sensory systems, especially the projection circuits of olfactory, visual, and auditory systems, to provide references for the mechanistic study of related mental disorders.