Development of brain stimulation reward in the medial prefrontal cortex: facilitation by prior electrical stimulation of the sulcal prefrontal cortex.

Electrical stimulation of the medial prefrontal cortex (MC) in rats delivered daily for seven days causes a marked improvement in the rate of acquisition of a self-stimulation response. In the present experiment, we looked at whether we could get the same facilitatory effect on self-stimulation of the MC by delivering pre-training stimulation to other points in the brain anatomically related to the MC. Electrical stimulation of the lateral hypothalamus was without effect. However, electrical stimulation of the sulcal prefrontal cortex (SC) either contralateral or ipsilateral to the MC electrode did facilitate acquisition of self-stimulation of the MC. Thus the Sc and MC would appear to be part of the same substrate controlling the development of positive reinforcement in the MC.