Alcohol impairs learning and timing of conditioned eyeblink responses.

Alcohol impairs motor performance, but it remains unclear precisely why this is the case. Here, we examine the effects of alcohol intoxication on conditioned eyeblink responses, a form of classical conditioning dependent on the cerebellum. In experiment 1, the conditioned responses of 18 students before and after alcohol consumption up to 1 ‰ were compared against the performance of 26 non-drinking controls. In experiment 2, 17 students were tested repeatedly at increasing blood alcohol levels up to 1 ‰. The results reveal a gradual decrease in both the percentage and timing of conditioned responses following alcohol consumption, with pronounced impairments emerging at blood alcohol content levels exceeding 0.5 ‰. These findings are consistent with the idea that the motor deficits associated with alcohol consumption are linked to effects on the cerebellum.