The ventral hippocampus mediates experience-dependent social modulation of fear in rats

Fear Conditioning by Proxy (FCbP) is a form of socially mediated fear learning, in which no-conditioned rodents acquire fear memories through social interactions with fear-conditioned rodents. This study investigates the impact of prior similar experiences on the transmission of contextual fear memories in FCbP and explores the role of the ventral hippocampus (vHPC) in the social transmission of fear. Observers were divided into two groups: those with contextual experience (D/O) and those without contextual experience- naïve (O). These rats were exposed to fear-conditioned demonstrators (D) through social interaction, and their responses to fear contexts were observed. Additionally, the effect of vHPC inactivation on fear memory transmission was examined by injecting lidocaine into the vHPC. Fear was transmitted through social interaction among experienced rats but not among naive rats. Furthermore, lidocaine injection into the vHPC inhibited the social transmission of fear memories among experienced rats. This study demonstrates that contextual fear memories can be transmitted through social interaction among experience-dependent rats but not among naive rats. That inactivation in the vHPC blocks the social transmission of contextual fear memories.