Anatomical and functional study of the gabaergic and glutamatergic cell groups in the cuneiform nucleus

Abstract

The cuneiform nucleus (CUN) is a midbrain structure located laterally to the caudal part of the periaqueductal gray matter. Hodological studies show that CUN is part of the neural system that integrates anti-predatory defense responses. Importantly, CUN has both glutamatergic and gabaergic cell bodies. Preliminary findings from our laboratory have shown that optogenetic stimulation of both glutamatergic cells and gabaergic cells in the CUN elicits defensive behaviors. In this project, we propose the investigation of the differential role of these two CUN cell populations in the defensive behavior. Initially, we will investigate the differential projection pattern of the CUN glutamatergic and gabaergic cell groups. Then, through optogenetic stimulation, we will establish the behavioral pattern from the selective stimulation of the glutamatergic and gabaergic groups of the CUN. This selective optogenetic stimulation will be followed by an analysis of FOS protein expression in neural sites differentially mobilized by CUN glutamatergic and gabaergic neurons. In order to broaden our understanding of the distinct neural populations of the CUN in the organization of the defense response, we will record through calcium imaging by using optical fiber photometry the differential cellular activity of the CUN glutamatergic and gabaergic cells in the situation of exposure to the predator (i.e., exposure to the cat) as well as exposure to the predatory context. Finally, once we have established the relationship between the cellular activity of the different neuronal groups of the CUN and specific defense responses, we will establish how selective optogenetic inactivation of glutamatergic and gabaergic groups influences innate and contextual anti-predatory responses. (AU)