Responses of midbrain raphe neurons to ethanol

The effects of ethanol on single midbrain raphe neurons were studied in the rat. For dorsal raphe neurons, only the units with rhythmic slow firing were consistently inhibited by ethanol. Those units often exhibited periodic cessation of spontaneous discharges in the initial responses, but later showed a dose-related slowing of discharge rates. Although median raphe neurons were also inhibited by ethanol, their responses consisted of an early tendency to fire more regularly, and then a decrease in spontaneous activity with bursting discharges. The data indicate that ethanol exerts different modes of inhibition on these two functionally different cell groups in the midbrain raphe complex.