The observation that the hippocampus is required for memory and spatial navigation has led to extensive study of the hippocampal neural circuit. Past research has focused on established patterns of hippocampal neural activity, such as the classic place cell code and the theta network pattern. However, we still have only a preliminary understanding of how the hippocampus performs cognitive functions. This may be the case because there still remain unknown yet fundamental patterns of hippocampal neural activity.

To investigate this possibility, we recorded neural activity in the hippocampus of rats engaged in a spatial memory task. In this thesis I describe four previously unidentified patterns of hippocampal neural activity: (1) spatially specific neural firing that is more active when animals are at rest, (2) a ~200 ms network pattern that is associated with spatial firing at rest, (3) spatially specific, transient neural firing at the time of behavioral transitions between movement and rest, and (4) a high frequency (65-140 Hz) network pattern that entrains neural firing throughout the hippocampus. I postulate that these patterns of activity have essential roles in complex hippocampal functions.