Auditory cue preceding intracranial stimulation induces event-related potential in rat frontal cortex: Alterations by amphetamine

Slow potential (SP) responses to a click followed by rewarding stimulation of the medial forebrain bundle (MFB) were recorded from the frontal cortex of rats with permanently implanted electrodes. Trials were presented at variable intervals and the final interval between the click and MFB stimulation was 2 seconds. Negative SP responses developed rapidly with training, as the interstimulus interval was gradually increased from 0.5 sec to 2 sec. No decrement of the SP response was observed during recording sessions consisting of more than 300 trials. The SP responses remained stable over several weeks of recording. Dextroamphetamine produced a dose-related depression of the SP responses. Since the effect of amphetamine in this study was similar to the effect in studies using food reinforcement, the results suggest that amphetamine-induced depression of event-related slow potentials in rat frontal cortex is not dependent on the type reinforcement. Advantages of the use of intracranial stimulation as reinforcement for event-related potential studies are discussed.