Electrophysiological characteristics of neurons in forebrain regions implicated in self-stimulation of the medial forebrain bundle in the rat.

In an attempt to identify neurons likely to play a role in self-stimulation of the medial forebrain bundle (MFB), action potentials of single neurons in the septum and basal forebrain of anesthetized rats were recorded by means of extracellular electrodes. Refractory period estimates were obtained from cells antidromically activated by stimulation of the lateral hypothalamus or ventral tegmental area, and estimates of interelectrode conduction time were obtained from cells that were driven by stimulation of both sites. The results show that some descending MFB axons arising in the medial septum, diagonal band of Broca and neighboring forebrain structures have characteristics comparable to properties of MFB reward neurons inferred from behavioral experiments.