"Shut up!" An electrophysiological study investigating the neural correlates of vocal inhibition

A neural biomarker that can be applied to studies of oral communication disorders would provide a boon to researchers. While there has been much research conducted on manual response inhibition, very few studies have examined vocal response inhibition. To date, no study has examined the temporal aspects of vocal inhibition. Therefore, the present study attempted to identify the neural correlates of vocal response inhibition by recording electroencephalographic activity during a modified version of the stop signal task. We included an ignore signal condition matched for frequency and visual stimulation to the stop signal which importantly, was included in the same block of trials as the typical go and stop trials. Behavioural results showed that participants were able to inhibit a vocal response within approximately 324 ms. Statistical analysis of ERPs revealed that a positive component around 324 ms was significantly larger in amplitude during successfully stopped trials compared to in an ignore condition, particularly over a cluster of fronto-central electrodes. These results support the notion that the P3 component is a reliable index of vocal inhibition.