Brain interactions underlying speech monitoring in language production

This study investigates functional connectivity patterns between brain regions supporting speech monitoring in seven participants with epilepsy undergoing stereotactic electroencephalographic (SEEG) monitoring and participating in a picture-word interference (PWI) task. Using graph signal processing (GSP) techniques, we found that three brain regions previously associated with speech monitoring processes, namely the anterior cingulate cortex (ACC), superior temporal gyrus (STG), and insula, functionally interact with each other and other regions around vocal onset and that these connections are more probable in errors than correct trials. Furthermore, the timing of their involvement in functional connectivity metrics indicates that they play distinct yet complementary roles in inner and outer speech monitoring. Specifically, the ACC maintains constant connectivity patterns before and after vocal onset, suggesting a continuous role in proactive and reactive speech monitoring. The STG shows stronger connectivity after vocal onset, consistent with its role in processing auditory feedback and external monitoring. Conversely, the insula exhibits stronger connectivity before vocal onset than after, suggesting that it plays a role in articulatory planning and inner speech monitoring. Our results align with the conflict-based account of speech monitoring in language production and suggest that inner and outer speech monitoring are supported by dynamic interactions between key brain regions of a network.