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.
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.
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