NEUROBIOLOGICAL MODELS OF SPATIAL PROCESSING

One of the aims of this chapter is to present models which deal with the implementation by the brain of spatial processing and memory. Some of these models exclusively concern the hippocampus, either because they account only for one specific type of encoding (setting up of place-cell firing fields: Sharp; distance encoding: Muller and coworkers), or because the basic assumption is that the hippocampus can perform all of the stages in the process (O’Keefe). Other conceptions rely on the cooperation of the hippocampus with neocortical structures, such as the parietal cortex (Poucet; McNaughton and coworkers). Finally, four general models of memory are presented (Teyler and DiScenna; Miller; Damasio; McClelland and coworkers). Although these models are not specifically aimed at accounting for spatial processing, these are of interest in the present context: in Chapters 7 and 8, I have presented several data which strongly suggest that the associative parietal and prefrontal cortices, and to a lesser extent the occipital area, do subserve complementary spatial functions. Consequently, it is of importance to have some insight, or, at least, hypotheses about how their possible interactions and cooperation with the hippocampal system may be implemented within the brain. In this respect, theories concerning the neural substrates and evolution over time of memories in general provide interesting perspectives which can be applied to spatial memories in particular. Indeed, the memory components of spatial processing can be reasonably thought to be controlled by the same brain mechanisms as those involved in the memory components of any other type of processing (of comparable cognitive level).