Electrophysiological correlates of behavioural inhibition and decision making processes in patients with impulse control deficits

Introduction:

Patients with impulse control deficits often show cognitive abnormalities especially in executive abilities e.g. working memory, planning capacity and behavioural inhibition. One possibility to examine the neurophysiological underlying mechanisms of these cognitive deficits is to assess evoked potentials. In the present study an adapted go/nogo-paradigm was used to investigate electrophysiological correlates of voluntary selection and behaviour control processes in patients suffering from alcohol dependence.

Methods:

14 patients with alcohol dependence (age=45.86±9.14) and 14 control persons (age=42.29±9.30) were included into the study. Patients with alcoholism were examined twice: before and after an inpatient detoxification. The participants performed a go/nogo task, comprising three different conditions: Apart from go-condition (button press required) and the nogo-task (inhibition of a behavioural response), a voluntary selection task was included in which participants were allowed to freely decide, whether to press the response button or not.

Results and discussion:

Response inhibition and voluntary selection processes were related to a fronto-central negativity after 200ms (N2) and positivity after 300ms (P3) in healthy subjects. Alcohol dependent patients did not show a N2 potential. In first examination, the P3 amplitude was reduced in patients compared to the controls. However, during the second examination the P3 amplitude was enhanced compared to the first examination. The results indicate that fronto-central brain regions participate in behavioural inhibition and voluntary selection processes. Smaller P3 are probably an indicator of dysfunctional inhibitory processes in alcohol dependent patients. The P3 varation returned to normal after the detoxifikation.