Fast trial-by-trial fronto-parietal cortical dynamics of conflict detection and context updating in a flanker task

The traditional N2 and P3 components of the human event-related potential (ERP) have been associated with successful cognitive control. However, recent research has found that the traditional target P3 consists of a mixture of stimulus-locked, response-locked, and latency variable P3-like positivities that can be functionally and topographically dissociated from one another. The current study aimed to extend previous results by examining target N2 and P3-like subcomponents indexing conflict detection and context updating at both low- and high-order levels in the neural hierarchy during control of target detection in a flanker task. Electroencephalographic (EEG) signals were recorded from 45 young adults while they completed a hybrid go/nogo flanker task, and Residue Iteration Decomposition (RIDE) was applied to functionally dissociate these peaks and establish their roles in conflict detection and context updating. Frequentist and Bayesian analyses showed a stimulus-locked frontal N2 revealing early conflict detection and fast categorization of nogo, congruous and incongruous trials, resulting in subsequent frontal P3-like activity (high-order context updating) elicited by infrequent nogo trials in the latency-variable RIDE cluster, and by the perceptually difficult incongruous trials in the response-locked cluster. In turn, the perceptually easier and more frequent congruous trials did not elicit frontal P3-like activity, although all trial types did elicit parietally distributed P3-like activity (low-order context updating), mostly within the latency-variable cluster. These novel findings support the presence of up to three distinct high-order task-set units regulating performance in our flanker task, as indexed by split-second, dynamic information transmission across frontal and parietal scalp regions.