Psychotropic Drug Effects on Self-Stimulation of the Brain: A Control for Motor Output

Rats with electrodes in the posterior lateral hypothalamus were trained in a chamber having two platforms. When standing on one platform, S received rewarding brain stimulation continuously. Switching to the other platform turned stimulation off. The proportion of time spent on the positive platform indicated the reward value of stimulation. Preliminary tests determined that the time measure was positively related to stimulation intensity. Drug tests determined that tranylcypromine and methamphetamine greatly increased the reward value of weak stimulation, while chlorpromazine greatly decreased the reward value of strong stimulation. Since Ss were not required to work for brain stimulation, these effects on reward value were shown not to be mere artifacts of the drugs' effects on motor output.