THE REPRESENTATION OF SPACE AND THE HIPPOCAMPUS IN RATS, ROBOTS AND HUMANS

Experimental evidence suggests that the hippocampus represents locatio ns within an allocentric representation of space. The environmental in puts that underlie the rat's representation of its own location within an environment (in the firing of place cells) are the distances to wa lls, and different walls are identified by their allocentric direction from the rat. We propose that the locations of goals in an environmen t is stored downstream of the place cells, in the subiculum. In additi on to firing rate coding, place cells may use phase coding relative to the theta rhythm of the EEG. In some circumstances path integration m ay be used, in addition to environmental information, as an input to t he hippocampal system. A detailed computational model of the hippocamp us successfully guides the navigation of a mobile robot. The model's b ehaviour is compared to electrophysiological and behavioural data in r ats, and implications for the role of the hippocampus in primates are explored.