Evaluation of cognitive control and distraction using event-related potentials in healthy individuals and patients with multiple sclerosis

Multiple Sclerosis (MS) is a disorder of the central nervous system that can result in cognitive dysfunction. Despite the prevalence of cognitive impairments in MS, few studies have directly examined dysfunction in the domain of cognitive control, which involves the monitoring of conflicting stimulus input and response options and the subsequent selection of an appropriate response (and inhibition of inappropriate responses). The present study examined event-related potential (ERP) indices of brain function in MS patients and healthy controls (HCs) for a Go/Nogo Flanker task of cognitive control. The task required participants to respond appropriately to a central target arrow stimulus that was flanked by non-target stimuli that were congruent, incongruent, or neutral with respect to the target. On some trials, a two-sided target arrow was presented, which required the inhibition of a response (Nogo). The Nogo stimulus also was surrounded by flankers (arrow primes or neutral). MS patients had slower reaction times during Go trials compared to HCs. Patients exhibited prolonged latencies for P1, frontal P2, N2, and P3 components compared to HCs. MS patients, compared to HCs, also had a more pronounced anteriorization for P3 amplitude during Nogo compared to Go trials, possibly indicating inhibitory dysfunction. Finally, decreased amplitude was also observed in MS patients compared to HCs for a positive-negative complex with very early latency onset, which may reflect dysfunction in early processing of the flanker stimuli. The findings indicate dysfunction at multiple stages of processing in MS patients during cognitive control.