Neurological reactivity during medial prefrontal cortex stimulation: effects of self-stimulation experience.

Electrical stimulation of the medial prefrontal cortex (MFC) induced a moderate behavioral suppression in a series of neurological tests that included measures of (1) open field activity (2) righting and climbing reflexes (3) somatosensory reactivity and (4) approach-withdrawal responsiveness to positive and negative stimuli. The same animals were trained to lever press for medial prefrontal cortex stimulation and after several days of self-stimulation were again tested for neurological reactivity during MFC stimulation. No habituation or lessening of behavioral suppression was evident as a result of self-stimulation experience. Therefore behavioral suppression, by itself, cannot account for the slow acquisition of MFC self-stimulation. Other data suggest that the stimulation interferes with the learning of complex operant responses and/or that the reward value of the stimulation is increased as a result of repetition.