Study of the cortical circuitry involved in contextual fear processing to predatory threat

Abstract

Previous studies from our laboratory showed that memory to predatory threats depends on a hypothalamic-thalamic path involving the dorsal premammillary nucleus and the ventral part of the anteromedial thalamic nucleus (AMv). Thus, it has been shown that cytotoxic lesions of the AMv interfere with the contextual, but not innate, responses to predatory threats. Connective data from our lab have shown that the AMv projects to a cortical network including the prelimbic, anterior cingulated and retrosplenial areas, likely to be involved in the memory processing to predatory threats. Previous studies have shown that the anterior cingulated and retrosplenial areas are involved in contextual fear memory to footshock, an effect mediated though projections to the post-rhinal area, an important source of inputs to the hippocampal formation. In the present study, our first aim is to investigate the projection pattern of each element of this cortical network (i.e., anterior cingulated, retrosplenial and post-rhinal areas), and next, by placing electrolytic lesions, we will examine the putative role played by each of this cortical fields in the contextual memory to predatory threats. Once established the main cortical fields involved in this process, pharmacological inactivation of selected cortical fields will be planned before the exposure to the predator or the predator-related context, to determine potential roles, respectively, in the acquisition or expression of contextual fear memory. (AU)