Neurophysiological correlates of response production and inhibition in alcoholics.
Scalp recordings of the P300 component of the event-related potential were made from a group of medication-free, chronic male alcoholics and a control group, participating in a visual Go/No Go reaction time paradigm. Subjects were presented with large and small forms of the letters T and V. The large forms (Go stimuli) required a button press with either the left or right hand, whereas the small forms (NO Go stimuli) required response inhibition. Recordings were made from 31 electrodes that, for statistical analyses, were grouped into five regions: frontal, central, parietal, occipital, and temporal. The results indicated that, in each of the five regions, both Go and NO Go response amplitudes were larger in the controls than in the alcoholics. No group differences in latency were observed in any region. Surface energy (Wang et al., Brain Topogr. 6:193-202, 1994) magnitudes paralleled P300 amplitudes and in the controls, compared with the alcoholics, were larger during both Go and No Go trials. Our findings suggest that abstinent, chronic alcoholics differ electro-physiologically from control individuals. These differences are manifested as widespread reductions in P300 amplitudes during the performance of a simple information processing paradigm. The reduced amplitudes may reflect a deficiency in an inhibitory mechanism proposed to underlie P300 generation.