Response inhibition in adults who stutter: A behavioral and event-related potential study during a visual stop signal task

Introduction: Stuttering is a neurodevelopmental disorder with structural and functional neurological bases characterized by involuntary prolongations, repetitions and blocks in sounds, syllables and words. Multiple factors are assumed to participate in etiology and severity of stuttering and response inhibition is considered to be an important phenomenon for having a fluent speech. Therefore, this study aimed to evaluate response inhibition of Adults Who Stutter (AWS). Materials and Methods: In a case-control study, response inhibition of twenty-eight AWS and fluently-matched control group was compared by a visual stop-signal task and its evoked potentials in the brain. Behavioral measurements of the task, including the Reaction Time (RT) and the response accuracy, were compared between the two groups. Peak amplitude and peak latency of P3 and N2 components in parietal and frontal areas were measured after cue, go and stop stimuli in different trials of the task. Results: Although AWS reported more scores in anxiety level, they acted similarly to the control group in behavioral measurements. ERP findings, however, represented smaller N2 amplitude in the cues and earlier N2 latency for the Go trials in AWS than in the controls. Conclusion: Our findings did not support the idea of less efficient inhibitory control in AWS; however, smaller N2 amplitude in the cues may indicated decreased attention resources allocated to the stimuli and different preparation for executing the response. Earlier N2 latency for Go trials in AWS also showed different timing of mental access to go stimuli and faster conflict monitoring in competing stimuli.