Role of the hippocampal system in associative learning beyond the spatial domain

Abstract

Expert opinion remains divided on the issue of whether the hippocampal system functions exclusively in spatial information processing, e.g. in navigation or in understanding spatial relations, or whether it plays a more general role in higher brain function. Previous work on monkeys and rats has tended to support the former view, whereas observations in the clinic point to the latter, including functions as diverse as declarative knowledge, episodic memory, word learning, and understanding relations among objects. One in¯uential theory posits a general role for the hippocampal system in associative learning, with emphasis on associations learned rapidly and recently. The results presented here are consistent with this theory, along with previous clinical and theoretical studies indicating that the hippocampal system is necessary for associative learning even if no component of the association relies on spatial information. In the study reported here, rhesus monkeys learned a series of conditional stimulus±response associations involving complex visual stimuli presented on a video monitor. Each stimulus instructed one of three responses: tapping the stimulus with the hand, steady hand contact with the stimulus for a brief period of time, or steady contact for a longe