RECENT PRESENTATIONS

Smith, M.E. & Gevins, A.S. (2005). Specificity of the acute effects of alcohol on neurophysiologic measures of human brain function. Presented at the annual meeting of the Research Society on Alcoholism, June, Santa Barbara, CA.

ABSTRACT

Alcohol intoxication produces a "neurophysiologic alcohol response" (NAR) characterized by increased theta and alpha band EEG amplitude most prominently over dorsolateral prefrontal cortex. Here we characterize the specificity of this response between genders and across a variety of task conditions performed by subjects. We also determine how the NAR is affected by pharmacological interventions that affect alertness. According to a double-blind, placebo-controlled, cross-over protocol, multi-channel EEG was recorded from N=16 (8 women) healthy young adult social drinkers during four test sessions in which they consumed either placebo, a dose of alcohol adequate for producing a peak blood breath alcohol level of 0.08, 200 mg. caffeine, or 50mg. of the sedating antihistamine diphenhydramine (Benedryl). During each session subjects were tested at a pre-ingestion baseline interval and at four post-ingestion intervals, the first of which commenced 30min after ingestion and the others hourly thereafter. During each test interval data were recorded during a task battery that included easy and difficult "n-back" working memory tasks, an easy reaction time task ("psychomotor vigilance task"), a difficult multitasking flight simulator task, and resting. Across the group participants produced the expected NAR in response to the alcohol challenge, with a maximal effect by 90min post ingestion and persisting up to the last test interval at 3 hours and 30 minutes. Although peak blood breath alcohol concentration levels did not differ between genders, the NAR was significantly larger in the women. The magnitude of the NAR did not differ across task conditions, suggesting that it was relatively independent of behavioral state. The NAR was distinct from any changes to the EEG spectrum produced by caffeine or diphenhydramine, suggesting that the effect does not simply reflect some overall change in alertness. Characterization of the neuronal mechanisms that produce the NAR may help clarify the acute consequences of alcohol consumption on human brain function. Since the EEG is easily recorded from active subjects, the NAR may also be useful in a variety of research contexts on alcohol's effects on the brain and behavior. Research supported by the NIAAA.