Impaired motor inhibition in adults who stutter - evidence from speech-free stop-signal reaction time tasks.
Idiopathic stuttering is a fluency disorder characterized by impairments during speech production. Deficits in the motor control circuits of the basal ganglia have been implicated in idiopathic stuttering but it is unclear how these impairments relate to the disorder. Previous work has indicated a possible deficiency in motor inhibition in children who stutter. To extend these findings to adults, we designed two experiments to probe executive motor control in people who stutter using manual reaction time tasks that do not rely on speech production. We used two versions of the stop-signal reaction time task, a measure for inhibitory motor control that has been shown to rely on the basal ganglia circuits. We show increased stop-signal reaction times in two independent samples of adults who stutter compared to age- and sex-matched control groups. Additional measures involved simple reaction time measurements and a task-switching task where no group difference was detected. Results indicate a deficiency in inhibitory motor control in people who stutter in a task that does not rely on overt speech production and cannot be explained by general deficits in executive control or speeded motor execution. This finding establishes the stop-signal reaction time as a possible target for future experimental and neuroimaging studies on fluency disorders and is a further step towards unraveling the contribution of motor control deficits to idiopathic stuttering.
Department of Psychology, University of Bonn, Germany; Center for Economics and Neuroscience, University of Bonn, Germany.
Sebastian
S
Markett
Department of Psychology, University of Bonn, Germany.
Benjamin
B
Bleek
Department of Psychology, University of Bonn, Germany; Center for Economics and Neuroscience, University of Bonn, Germany.
Martin
M
Reuter
Neurology (Stuttering Therapy), LVR Clinics Bonn, Germany.
Holger
H
Prüss
Neurology (Stuttering Therapy), LVR Clinics Bonn, Germany.
Kirsten
K
Richardt
Neurology (Stuttering Therapy), LVR Clinics Bonn, Germany.
Thilo
T
Müller
Department of Communication Science & Disorders, University of Pittsburgh, PA, USA.
J Scott
JS
Yaruss
Department of Psychology, University of Ulm, Germany; Key Laboratory for Neuroinformation/Center for Information in Medicine, University of Electronic Science and Technology, Chengdu, China.
Christian
C
Montag
D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D030141:Feedback, Psychological; D005260:Female; D006801:Humans; D008297:Male; D009069:Movement Disorders / Q000209:etiology*; D009433:Neural Inhibition / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D017603:Signal Detection, Psychological; D013060:Speech / Q000502:physiology; D013061:Speech Acoustics; D013068:Speech Production Measurement; D013342:Stuttering / Q000150:complications*; D055815:Young Adult
Executive control; Fluency disorder; Motor inhibition; Speech production; Stop-signal reaction time; Stuttering