Modeling Interactions of the Rat's Place and Head Direction Systems

We have developed a computational theory of rodent navigation that includes analogs of the place cell system, the head direction system, and path integration. In this paper we present simulation results showing how interactions between the place and head direction systems can account for recent observations about hippocampal place cell responses to doubling and/or rotation of cue cards in a cylindrical arena (Sharp et al., 1990). Rodents have multiple internal representations of their relationship to their environment. They have, for example, a representation of their location (place cells in the hippocampal formation, see Muller et al., 1991), and a location-independent representation of their heading (head direction cells in the postsubiculum and the anterior thalamic nuclei, see Taube et al., 1990; Taube, 1995). If these representations are to be used for navigation, they must be aligned consistently whenever the animal reenters a familiar environment. This process was examined in a set of experiments by Sharp et al. (1990). 1 The Sharp et al., 1990 experiment Rats spent multiple sessions finding food scattered randomly on the floor of a black cylindrical arena with a white cue card along the wall subtending 90 of arc. The animals were not disoriented before entering the arena, and they always entered at the same location: the northwest corner. See Figure 3a. Hippocampal place fields were mapped by single-cell recording. A variety of probe trials were then introduced. When an identical second cue Visual Input Local View Place Code Path Integrator Head Direction Vestibular Input Motor Efference Copy Goal Memory Φh Ti ri φi , , 〈 〉