Ethanol effects on volitional versus reflexive saccades

The effects of a moderate alcohol dose on reflexive and volitional saccades were compared. Healthy male subjects (n = 17) made horizontal reflexive saccades, antisaccades and self-paced saccades before and after the ingestion of a body-weight-related dose of alcohol. At a mean blood alcohol concentration of 0.044%, reflexive saccade latency significantly increased although accuracy remained unimpaired at each target amplitude. No significant ethanol effects were noted for antisaccade accuracy and latency. Antisaccade error rates decreased significantly, likely demonstrating a learning effect. The mean rate of self-paced saccades did not significantly change post-ethanol and their accuracy was also unimpaired. All saccades share a final common pathway for their execution. It thus seems reasonable to propose that ethanol modulated connections between the posterior parietal cortex and superior colliculus to increase reflexive saccade latency. Higher-order paradigms, which require inhibition and are mediated by frontal areas, might be impaired at greater blood alcohol concentrations.