Seeking neurophysiological manifestations of speech production: An ERP study

The aim of this study was to examine the neurophysiological correlates of speech production by elucidating pertinent ERP components. Such examination can pave way for investigations on typical and atypical speech neuromotor control. Participants completed a speech task by saying a specific word (speaking condition) or withholding the verbal response (non-speaking condition) based on the color of a frame placed around a fixation cross that were displayed on a computer screen. They also completed a simple hand motor task by pressing a button with the right or left index finger based on the color of a frame. The hand motor task was administered to verify that neural activity specific to motor preparation was detectable. Two ERP components emerged from the multichannel principal component analysis (PCA) as distinguishing between the speaking and no speaking conditions: a posterior negative component, and a left lateralized positive component. The morphology of the posterior negative component, as well as the correlation between its magnitude and mean response time suggest that this component is closely associated with speech motor control. The left-lateralized component was interpreted as reflecting a process possibly mediated by the speech dominant left hemisphere.