Enhancement of performance for brain stimulation reward after footshock in rats.

Rats bearing electrodes in the anterior forebrain region (AF), lateral hypothalamus (LH) or dorsal raphe (DR) nucleus were trained to press lever for brain stimulation reward. Ten minutes self- stimulation in all these placements produced a lowering of pain sensitivity as assessed by the hot-plate test. Electric footshock administered on 1 s on/4 s off paradigm for 10 min prior to self-stimulation elevated lever pressing rates in AF rats and in part of LH rats, but not in DR rats. The results are discussed in terms of opiate theory of reinforcement.