Temporal coding of conspecific position in the hippocampus

Abstract

The aim of this experiment was to determine whether the hippocampus formed a representation of the location of another animal. It was hypothesized that place cells in the hippocampus would encode spatial information regarding the location of a conspecific in an observation task where no movement planning was required of the observer. Four male Sprague Dawley rats (2 pairs) were used to examine these hypotheses. The pairs of rats were trained to shuttle in a box and were then habituated to an ‘observer box’. Single unit hippocampal data was collected from the observer both in the run condition (the observer itself shuttled backward and forward) and then in the watch condition (the observer was observing a conspecific shuttling). A small but significant correlation was observed between the place field locations in the run and watch conditions. In addition, significant theta phase precession occurred in the hippocampus based on the conspecific’s location. The hypotheses were supported and together the results suggested that the hippocampus encodes a social component of memory which has the ability to represent spatial location information of a conspecific. This representation could use both rate and temporal codes. These data suggest that the hippocampus could be a potential therapeutic target for disorders with impaired social function, such as schizophrenia.