Subject control as a determinant of the reinforcing properties of intracranial stimulation

There has been some controversy whether experimenter-administered electrical stimulation of the brain is aversive or simply less reinforcing than that delivered via self-stimulation. Rats with MFB-LH electrodes self-stimulated with high, medium, and low currents and the self-produced rates were tape recorded. In Experiment 1, the rats were allowed to choose between self-administered versus replayed ESB. When both types of stimulation were available at medium intensities, the rats preferred to self-administer the ESB. This preference was increased when the re-played stimulation was presented at a lower intensity than the self-administered ESB. However, the preference for contingent ESB decreased when the intensity of the experimenter administered ESB was increased suggesting that experimenter-administered ESB is not aversive. In Experiment 2, the rats chose between experimenter administered ESB delivered at the played-back self-generated rate versus a regular averaged rate. All Ss preferred the previously self-generated mode. In Experiment 3, the rats were deprived of water and given four daily competition tests between experimenter administered ESB versus water. All rats "self-dehydrated" again demonstrating that experimenter-administered ESB is not aversive. It is concluded that rats prefer to control the rate at which ESB is presented, but that non-contingent stimulation is clearly not aversive.