Hippocampal Place-like Signal in Latent Space

Abstract

During navigation, the hippocampus represents physical places like coordinates on a map; similar location-like signals have been seen in sensory and concept spaces. It is unclear just how general this hippocampal place code is, however: does it map places in wholly non-perceivable spaces, without locations being instructed or reinforced and during navigation-like behavior? To search for such a signal, we imaged participants' brains while they played a naturalistic, narrative-based social interaction game, and modeled their relationships as a kind of navigation through social space. Two independent samples showed hippocampal place-like signals in both region-based and whole-brain representational similarity analyses, as well as decoding and average pattern similarity analyses; the effects were not explained by other measures of the behavior or task information. We also replicated and extended previous findings of hippocampal tracking of the egocentric angle in social space. These results are the first demonstration of complete domain generality in hippocampal place representation.