Characterization of the acute effects of alcohol on asymmetry of inferior frontal cortex activity during a Go/No-Go task using functional near-infrared spectroscopy

Rationale Successful response inhibition is associated with right-lateralized inferior frontal cortex (IFC) activity, and alcohol impairs this inhibitory control, thereby enhancing false-alarm responses in the Go/No-Go task. However, the neural correlates of effect of alcohol on response inhibition remain unclear. Objective This study characterized the acute effects of alcohol on IFC activity during Go/No-Go tasks using near-infrared spectroscopy (NIRS). Methods Thirty-two subjects visited our laboratory twice: once for alcohol intake and once for placebo intake. On each visit, subjects performed Go/No-Go tasks immediately before and 10 min after intake of the alcohol or placebo. NIRS was used to evaluate IFC activity measured during Go/No-Go tasks. Results Alcohol significantly enhanced false-alarm responses in No-Go trials. NIRS analysis showed that IFC activity was greater in the right hemisphere than in the left hemisphere prior to alcohol or placebo intake. This right hemispheric superiority was eliminated in response to alcohol but not in response to placebo. Correlation analysis showed that subjects with right-lateralized IFC activity made fewer false-alarm responses in No-Go trials and that alcohol-induced inhibition of hemispheric IFC asymmetry resulted in higher false-alarm rates. Conclusion These findings suggest that the right IFC may mediate the acute effects of alcohol on inhibitory control. When the alcohol impairs the right IFC activity, subjects cannot inhibit the pre-potent responses for No-Go trials, resulting in enhanced false-alarm responses. Thus, this study successfully demonstrated the neural correlates of the alcohol effect in the right IFC activity during inhibitory control processes.