Event-related potentials in a Go/Nogo task of abnormal response inhibition in heroin addicts

Inhibitory control dysfunction is regarded as a core feature in addicts. The major objective of this study was to explore the time course of response inhibition in chronic heroin addicts and provide the neu-rophysiological evidence of their inhibitory control dysfunction. The amplitudes and latencies of ERP components were studied in fourteen heroin addicts (mean duration of heroin use being (13.54±5.71) years (Mean±SD), average abstinence being ((4.67±6.44) months)) and fourteen matched healthy con-trols with a visual Go/Nogo task. Our results showed that heroin addicts demonstrated significantly larger Go-N2 amplitudes which results in a decreased N2 Go/Nogo effect, but no statistically significant differences were found between heroin addicts and controls in P3. The ERP data suggest that fronto-central areas of heroin addicts were impaired during the inhibition process (200—300 ms) and over-activated to targets. The impaired early process might reflect an abnormal conflict monitoring process in heroin addicts. These results consolidate the inhibitory control dysfunction hypothesis in chronic heroin users.