Hippocampectomized rats are capable of homing by path integration

Navigation in rodents is mediated by at least 3 mechanisms: guidance, path integration, and landmark learning. The hippocampus is necessary for spatial learning based on distal landmarks, and it has been suggested that the hippocampal formation performs a form of path integration in updating place cell firing; however, the necessity of the hippocampus for path integration has not been clearly established. Rats with extensive neurotoxin lesions of the hippocampus and control rats were trained on 2 tasks in which they were required to move in total darkness from one location to another and then return to the start point. Hippocampal and control rats both used path integration in solving these tasks and did not differ in terms of the distributions of their arrival points on the return paths. We conclude that neuronal circuits sufficient for computing a homing vector using path integration are located outside the hippocampus.