AUTHOR=Pan Ting-Ting , Liu Chao , Li De-Min , Zhang Tian-Hao , Zhang Wei , Zhao Shi-Lun , Zhou Qi-Xin , Nie Bin-Bin , Zhu Gao-Hong , Xu Lin , Liu Hua 

TITLE=Retrosplenial Cortex Effects Contextual Fear Formation Relying on Dysgranular Constituent in Rats

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 16 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2022.886858

DOI=10.3389/fnins.2022.886858

ISSN=1662-453X

ABSTRACT=Animal contextual fear conditioning (CFC) models are the most-studied forms used to explore the neural substances of posttraumatic stress disorder (PTSD). In addition to the well-recognized hippocampal-amygdalar system, the retrosplenial cortex (RSC) is getting more and more attention due to substantial involvement in CFC, but with a poor understanding of the specific roles of its two major constituents—dygranular (RSCd) and granular (RSCg). The present study sought to identify their roles and underlying brain network mechanisms during encoding processing of rat CFC model. Rats with pharmacologically inactivated RSCd, RSCg respectively and corresponding controls underwent electric foot shock contextual conditioning. 18F-FDG PET/CT scanning was performed for every animal. 5-hour and 24-hour retrieval followed to test the formation of contextual memory. Graph theoretic tools were used to identify the brain metabolic network involved in encoding phase, and changes of nodal (brain region) properties linked respectively to disturbed RSCd and RSCg were analyzed. Impaired retrieval occurred in disturbed RSCd animals not in RSCg ones. The RSC, hippocampus, amygdala, piriform and visual cortices are hub nodes of the brain-wide network for contextual fear memory encoding in rats. Nodal degree and efficiency of hippocampus and its connectivity with amygdala, piriform and visual cortices were decreased in rats with disturbed RSCd while not in those with suppressed RSCg. The RSC plays its role in contextual fear memory encoding mainly relying on its dygranular part whose condition would influence the activity of hippocampal-amygdalar system.