Oxazepam alters action monitoring

Rationale: Oxazepam has been demonstrated to slow reaction times and increa se the rate of omission errors in attentional experiments. This suggests th at action monitoring might also be impaired. Objectives. The present study used the event-related brain potential (ERP) technique to investigate this hypothesis. The P3b component to targets was taken as an indicator of the t arget evaluation process, and the response-locked error-related negativity (ERN) served as an indicator of action monitoring. We hypothesized that the amplitudes of ERN and P3b would be reduced as an effect of oxazepam. Metho ds. A simple "oddball" reaction time experiment was conducted in a double-b lind crossover study of 30 mg oxazepam versus placebo. In order to investig ate variations in attentional allocation, separate experimental runs were u ndertaken with target frequencies of 50% and 80%. Results. ERN and P3b ampl itudes were lower in the 80% target condition than in the 50% condition. Ox azepam did not affect behavioral parameters but was associated with an ERN of lower amplitude than the placebo condition. ERN amplitude variations bet ween target conditions remained unchanged. Conclusions: Although the intake of 30 mg oxazepam did not impair behavioral performance, measures of the e lectrophysiological recordings show that action monitoring processes were a ltered. We argue that this may he related to the anxiolytic properties of t he drug and may constitute an important causal factor for behavioral impair ments after the intake of oxazepam.