Chemical and Electrical Stimulation of Hippocampus in Unrestrained Animals

Abstract

In recent years there has been increasing interest in the role of the phylogenetically old cortex in viscerosomatic and emotional functions and in psychomotor epilepsy. The phylogenetically old cortex comprises the so-called archicortex and mesocortex. The archicortex and the greater part of the mesocortex are contained in the limbic lobe, which is found as a common denominator in the brains of all mammals. The "old" cortex and its associated nuclei constitute a functionally integrated system, which may be appropriately referred to as the limbic system.³⁶ Most of the archicortex is folded into the large cerebral convolution known as the hippocampus, or cornu ammonis. In addition to its cytoarchitecture, the hippocampus is distinguished from the rest of the brain by its peculiar, primitive end-arterial type of blood supply. It also possesses quite distinctive bioelectrical and biochemical properties (see MacLean^38,39for review and references). Clinical, anatomical, and physiological observations have