New perspectives on the neural processes underlying performance monitoring as revealed by simultaneous TMS-EEG

Ample findings suggest that the dorsal anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC) collaborate in solving cognitive conflict. The ACC is assumed to register and signal ongoing conflicts and errors. In contrast, the DLPFC is thought to implement (the signalled need for) cognitive control. Yet, the precise temporal and thus functional interactions between the two regions remain poorly understood. Here, we probed the role of ACC-to-DLPFC interactions in error processing through concurrent transcranial magnetic stimulation (TMS) and electroencephalography (EEG) while participants (n=38) performed a complex, error-prone task. Specifically, we applied online triple-pulse TMS over the right DLPFC (versus an active TMS control) in a 200 ms window after a behavioural response, targeting the period of error-related ACC activation. Our aim was to interfere with DLPFC at the time of error processing and/ or signal transmission from the ACC and assess the impact on related neural (i.e., the error-related negativity; Ne/ERN) and behavioural measures, such as post-error slowing (PES) and post-error accuracy (PEA). Additionally, we assessed EEG-predictors (i.e., CNV) of behavioural adjustments in the inter-trial interval (ITI). While no main effects of DLPFC-TMS were found on individual measures, we observed significant changes in the relationships between neural (Ne/ERN, ITI) and behavioural (PES, PEA) markers depending on the TMS condition.These findings indicate that DLPFC stimulation influenced the strategy of behavioural adaptation rather than its magnitude, highlighting the DLPFC’s role in implementing cognitive control. Our results further point to the pre-stimulus time as a key window for translating neural error signals into adaptive behaviour. Our study underlines the usefulness of combining time-sensitive neuroimaging and stimulation methods to unravel the functional interplay between neuronal and behavioural markers of adaptive cognition.