Ethyl alcohol effect on the visual evoked potential

The investigations were carried out in 30 clinically healthy pilots who were given 1 g/kg of body weight of ethanol orally. Visual evoked potentials were recorded 30 and 60 minutes after alcohol ingestion in the occipital leads using an ANOPS-10 computer. It was found that ethanol caused prolongation of the latency time of all components parallel with rising concentration of ethanol in the blood. The amplitude of the late components, i.e.-N2-P2-P2-N3 and N3-P3 30 minutes after alcohol ingestion was raised, and after 60 minutes it was reduced. The analysis of the individual visual evoked potentials demonstrated three types of individual reactions to ethanol. Type I--increasing depression of the amplitude of the components with rising blood alcohol concentration, type II--rising amplitude, mainly of the late components, type III--amplitude rise in the 30th minute followed by amplitude fall in the 60th minute without reaching, however, the initial level. These changes of the visual evoked potentials suggest that alcohol exerts in the first place an effect on the subcortical structures and that this effect is a phasic one.