| Rodent navigation is a unique domain for studying information processing in the brain because there is a vast literature of experimental results at many levels of description, including anatomical, behavioral, neurophysiological, and neuropharmacological. This literature provides many constraints on candidate theories. This thesis presents contributions to a theory of how rodents navigate as well as an overview of that theory and how it relates to the experimental literature.;In the first half of the thesis, I present a review and overview of the rodent navigation literature, both experimental and theoretical. The key claim of the theory is that navigation can be divided into two categories: taxon/praxic navigation and locale navigation (O'Keefe and Nadel, 1978), and that locale navigation can be understood as an interaction between five subsystems: local view, head direction, path integration, place code, and goal memory (Redish and Touretzky, 1997). I bring ideas together from the extensive work done on rodent navigation over the last century to show how the interaction of these systems forms a comprehensive, computational theory of navigation. This comprehensive theory has implications for an understanding of the role of the hippocampus, suggesting that it shows three different modes: storage, recall, and replay.;In the second half of the thesis, I show specific contributions to this overall theory: a simulation of the head direction system that can track multiple head direction speeds accurately, a novel hypothesis for the anatomical locus of the path integrator, simulations demonstrating the viability of the three-mode hippocampal proposal, simulations demonstrating the viability of the dual-role hippocampus (recall and replay).;In addition, I present simulations of specific experiments: a simulation of the recent result from Barnes et al. (1997), a simulation of Sharp et al. (1990), simulations of Cheng (1986) and Margules and Gallistel (1988), simulations of Morris (1981), as well as simulations of Collett et al. (1986) and our own gerbil navigation results. |
