The effects of d-amphetamine on the electrophysiological activity of the superior colliculus in the rat

The superior colliculus (SC) is thought to have an inhibitory effect on arousal (and hence activity) in rats when light is present. d-Amphetamine is believed to suppress this inhibition of the SC on arousal. The present study investigated the electrophysiological activity of the SC of the rat under the influence of d-amphetamine in both light and dark conditions. A single numerical arousal index value (AI) for the electrophysiological data obtained by dividing the frequency of the waves by the voltage over a specified interval was used. Results showed that light conditions decreased the AI of the SC. The AI was, however, not affected by d-amphetamine. Also, the electrophysiological activity of the SC showed spontaneous emissions of high-voltage (600 microV) alpha waves which generally occurred in two- to four-second bursts. Occurrence of this high-voltage activity was reduced by increasing doses of d-amphetamine.