Spatiotemporal dynamics of selective attention and visual conflict monitoring using a Stroop task.

Selective attention and conflict monitoring are daily human phenomena, yet the spatial and temporal neurological underpinnings of these processes are not fully understood. Current literature suggests these executive functions are thought to occur via diverse and highly interconnected neural networks, including top-down and bottom-up processing, as well as conflict-control loops. To investigate the spatiotemporal activity of these processes, we collected neuromagnetic data using magnetoencephalography (MEG) in 28 healthy adults (age 19-36) while they performed a computerized Stroop task based on color naming, an experiment used for decades to understand cognitive interference. We focused on low frequency oscillations in the context of top-down control, and we hypothesized that conflict monitoring-related activity would first be observed in the left anterior cingulate cortex, followed by the left dorsolateral prefrontal cortex, and subsequently in the parietal and temporal lobes. Significant activity between 600-1000 ms post stimulus onset was found for incongruent vs. congruent/neutral contrasts. Interestingly, spatiotemporal analysis did not provide evidence for a top-down pattern of activation, instead revealing a simultaneous pattern of activation in the frontal and temporal lobes. Most notable is the involvement of the left posterior inferior temporal cortex (pITC) and the left temporoparietal junction (TPJ), two structures that have not conventionally been considered active players in attentional control. These results may be largely driven by alpha and beta oscillations from our sample population. Our findings contradict early theoretical models of top-down processing associated with the modulation of cognitive control from an attention perspective and also suggests a need to investigate attentional centers in the temporal lobe. Furthermore, the study demonstrates the utility of MEG in providing temporal data that has been missing from previous studies.