Controllability of prestimulation of the medial prefrontal cortex determines the facilitation of self-stimulation and kindled seizures.
Electrical stimulation of the medial prefrontal cortex (MPC) was administered according to the triadic design typically used to demonstrate learned helplessness. Three groups received either controllable, uncontrollable or no stimulation during the pretreatment phase. The effects of this pretreatment on the acquisition of self-stimulation at the same electrode site were investigated in the second phase of the experiment. Relative to unstimulated controls, both controllable and uncontrollable prestimulation facilitated the acquisition of self-stimulation and produced higher self-stimulation rates. In addition, compared with controllable stimulation, pretreatment with uncontrollable stimulation produced a greater facilitation in self-stimulation rate. The unambiguous demonstration of a behavioural facilitation produced by pretreatment with uncontrollable stimulation is, effectively, the inverse of the typical learned helplessness finding. It was also found, in the second phase of the experiment, that 6 of the 7 rats previously exposed to uncontrollable stimulation developed full class 5 seizures. No behavioural evidence of kindling was seen in any of the other rats or during the prestimulation procedure. These data are interpreted in terms of kindling and stress effects both proximal and distal to the site of stimulation.