Acute effects of alcohol on evoked potentials in visual cortex and superior colliculus of the rat

This study examined the effects of alcohol on visually evoked potentials recorded from the primary visual cortex (VC) and superior colliculus (SC) of chronically implanted rats. Animals were given intraperitoneal injections of saline, and of 0.15, 0.5, 1.0 and 1.5 g ethanol/kg body weight on separate days. Evoked potentials were recorded at 5, 20, 40, and 60 min following injection. There were differential effects of both alcohol and habituation on the early versus late VC components. The amplitudes of the late components decreased over time and were also depressed by both the 1.0 and 1.5g/kg doses of alcohol. Amplitudes of the early components increased over time and were unaffected by the 1.0g/kg alcohol dose. The 1.5g/kg dose depressed the early negative component but augmented the early positive component. In contrast to the amplitudes, the latencies of both early components were increased at both the l.0 and 1.5g/kg doses. However, the latency of the late positive component was increased at only the 1.5 g/kg dose, while the latency of the late negative component was unaffected by any alcohol dose. In the SC, the peak amplitude of the early positive complex was unaffected by either habituation or alcohol. However, both the amplitude and latency of a later negative component (latency of 52 msec) were affected by alcohol. The 1.0 and 1.5g/kg doses decreased peak amplitude, while the latency was increased at the highest dose. These effects of alcohol on the SC component were in directions opposite to those resulting from habituation.