Subjective impulsivity and baseline EEG in relation to stopping performance.

Impulsivity is a personality trait within the normal population, but also a feature of many psychiatric disorders that have been associated with poor inhibitory control. The aim of the present study was to examine the relation between subjective impulsivity, theta/beta EEG ratio, and inhibitory control in healthy individuals. In 15 high and 14 low impulsive healthy volunteers (as assessed by the I(7) questionnaire), resting state EEG was recorded during an eyes open condition to obtain estimates for theta and beta activity. Subsequently, a stop-signal task was presented where participants responded to go-signals and had to stop their initiated response to stop-signals. Stopping performance and EEG activity were compared between the impulsive groups as well as between high vs. low theta/beta ratio groups. Results showed that subjective impulsivity was not related to stopping behavior or to theta/beta ratio. In contrast to our expectations that individuals with high theta/beta ratios would show relatively long stopping reaction times, analyses revealed that the low theta/beta ratio group had longer stopping reaction times. Given that increased theta/beta ratio may reflect reduced cortical inhibition over subcortical drives, it is proposed that healthy individuals with relative high theta/beta ratios are more motivated to maximize inhibition-related performance.