RESUMEN
Higher impulsivity may arise from neurophysiological deficits of cognitive control in the prefrontal cortex. Cognitive control can be assessed by time-frequency decompositions of electrophysiological data. We aimed to clarify neuroelectric mechanisms of performance monitoring in connection with impulsiveness during a modified Eriksen flanker task in high- (n = 24) and low-impulsive subjects (n = 21) and whether these are modulated by double-blind, sham-controlled intermittent theta burst stimulation (iTBS). We found a larger error-specific peri-response beta power decrease over fronto-central sites in high-impulsive compared to low-impulsive participants, presumably indexing less effective motor execution processes. Lower parieto-occipital theta intertrial phase coherence (ITPC) preceding correct responses predicted higher reaction time (RT) and higher RT variability, potentially reflecting efficacy of cognitive control or general attention. Single-trial preresponse theta phase clustering was coupled to RT in correct trials (weighted ITPC), reflecting oscillatory dynamics that predict trial-specific behavior. iTBS did not modulate behavior or EEG time-frequency power. Performance monitoring was associated with time-frequency patterns reflecting cognitive control (parieto-occipital theta ITPC, theta weighted ITPC) as well as differential action planning/execution processes linked to trait impulsivity (frontal low beta power). Beyond that, results suggest no stimulation effect related to response-locked time-frequency dynamics with the current stimulation protocol. Neural oscillatory responses to performance monitoring differ between high- and low-impulsive individuals, but are unaffected by iTBS.