Hippocampal cells have mnemonic correlates as well as spatial ones

The activity of complex spike cells in the hippocampus is strongly correlated with the location of a rat in a spatial environment. These results have led to the development of the cognitive mapping theory of hippocampal function. However, a considerable body of evidence from experiments examining the behavioral changes following lesions of the hippocampus emphasizes its role in memory (both spatial and nonspatial), rather than cognitive mapping. If the hippocampus plays a role in nonspatial mnemonic processes as well as in cognitive mapping, then the activity of complex spike cells in the hippocampus ought to be correlated with different types of mnemonic demands. In this article, we review the results from relevant experiments, which indicate that complex spike cells do have mnemonic correlates in some behavioral tasks. These results suggest that current theoretical interpretations of hippocampal function should emphasize both mnemonic and cognitive mapping processes.