Neural substrates of navigation and spatial cognition in the rat

This main purpose of this dissertation is to describe a set of three experiments that were designed to explore neural systems supporting navigation and spatial cognition. Additionally, the theoretical significance of the experiments and their relationship to the current literature will be discussed in detail. This introductory section provides some motivation for the study of navigation and spatial cognition, followed by an overview of the three experiments, a discussion of previous work leading to each experiment, and a brief description of the methodology used for each study. Experiment 1 utilizes high-density neurophysiological recording techniques to examine hippocampal place cell activity in cue-rich environments where the rats are exposed to cue conflict situations, and concludes that the hippocampal representation of spatial location is concordant. Experiment 2 takes advantage of the transynaptic retrograde transport of pseudorabies virus to define the synaptology of a pathway through which cells whose activity code for head direction could receive vestibular sensory information. Experiment 3 also uses pseudorabies virus to define polysynaptic pathways from the hippocampal formation to the hypothalamus via the lateral septum, which could provide the pathways for spatial information to be transported to areas involved in motivated behavior. The last chapter of this dissertation provides an extensive discussion of some issues surrounding the data presented, and brings together the experimental conclusions to construct generalizations regarding neural substrates of navigation and spatial cognition