From oscillations to single-unit activity: the neurophysiology of human spatial navigation

Kahana, M. J.
Center for Complex Systems, Brandeis University

The place cells of the rodent hippocampus, and the 4-10 Hz hippocampal theta rhythm, constitute two of the most striking examples of correlations between neuronal activity and complex behavior in mammals. Using human intracranial recordings, which can be ethically obtained as part of standard neurosurgical evaluations, we examine the neurophysiological basis of human spatial cognition. Field recordings from intracranial electrodes while subjects actively explored a virtual town revealed increased theta activity associated with movement and when searching for objects whose locations were not known. Single cell recordings from hippocampal, parahippocampal and frontal regions reveal cells in the hippocampus that respond at specific spatial locations and cells in parahippocampal region responding to views of landmarks. These data suggest that the hippocampus is specialized for spatial processing while the parahippocampal region is specialized for coding spatial views. Cells also responded to the subjects navigational goals and to conjunctions of place, goal and view.