MAPS, ROUTES, AND THE HIPPOCAMPUS - A NEURAL-NETWORK APPROACH

This study describes hippocampal participation in maze navigation in t erms of a real-time, biologically plausible neural network. The system is composed of (1) a goal-seeking mechanism, (2) a cognitive map syst em. and (3) a route system. The goal-seeking mechanism displays explor atory behavior until either the goal is found or a sufficiently strong prediction of the goal is generated. The cognitive map is a topologic al map that stores associations between places and views of accessible places, and between places and reward. The route system establishes a ssociations between cues and reward. Both systems compete with each ot her to establish associations with the reward, with the cognitive syst em generally overshadowing the route system. In agreement with previou s models. it is assumed that the hippocampus modulates the storage of cognitive maps in cortical areas and mediates the competition between cognitive maps and route systems. After hippocampal lesions, animals n avigate through mazes making use of the route system. Computer simulat ions show that the network effectively describes latent learning. deto ur behavior, and place learning in normal and hippocampal- and cortica l-lesioned animals.