Regional activities within the human hippocampus and hippocampal gyrus

Abstract

The rare opportunity to record from electrodes stereotactically implanted in man has made possible the study of the intrinsic electrical activity of several deep structures in the brain. Of necessity the recordings are not from normal brains, the patients in this series being cases of temporal lobe epilepsy in whom the electrodes have been positioned for diagnostic and lateralizing purposes. The results analyzed here are from the normal or less abnormal hemisphere in each case. In the report presented here, the results of exploration of the hippocampus and its relationships with the amygdala and ipsilateral hippocampal gyrus are described. Several types of analysis lead to the conclusion that, in terms of its electrophysiological characteristics, the hippocampus in man does not have uniformity throughout its length nor do all sectors of it share the same relationship with the amygdala or with the ipsilateral hippocampal gyrus.