When will a stuttering moment occur? The determining role of speech motor preparation.
The present study aimed to evaluate whether increased activity related to speech motor preparation preceding fluently produced words reflects a successful compensation strategy in stuttering. For this purpose, a contingent negative variation (CNV) was evoked during a picture naming task and measured by use of electro-encephalography. A CNV is a slow, negative event-related potential known to reflect motor preparation generated by the basal ganglia-thalamo-cortical (BGTC) - loop. In a previous analysis, the CNV of 25 adults with developmental stuttering (AWS) was significantly increased, especially over the right hemisphere, compared to the CNV of 35 fluent speakers (FS) when both groups were speaking fluently (Vanhoutte et al., (2015) doi: 10.1016/j.neuropsychologia.2015.05.013). To elucidate whether this increase is a compensation strategy enabling fluent speech in AWS, the present analysis evaluated the CNV of 7 AWS who stuttered during this picture naming task. The CNV preceding AWS stuttered words was statistically compared to the CNV preceding AWS fluent words and FS fluent words. Though no difference emerged between the CNV of the AWS stuttered words and the FS fluent words, a significant reduction was observed when comparing the CNV preceding AWS stuttered words to the CNV preceding AWS fluent words. The latter seems to confirm the compensation hypothesis: the increased CNV prior to AWS fluent words is a successful compensation strategy, especially when it occurs over the right hemisphere. The words are produced fluently because of an enlarged activity during speech motor preparation. The left CNV preceding AWS stuttered words correlated negatively with stuttering frequency and severity suggestive for a link between the left BGTC - network and the stuttering pathology. Overall, speech motor preparatory activity generated by the BGTC - loop seems to have a determining role in stuttering. An important divergence between left and right hemisphere is hypothesized.
Department of Internal Medicine, Neurology, Ghent University, Ghent University Hospital, De Pintelaan 185, 1K12A, B-9000 Ghent, Belgium; Department of Speech, Language and Hearing Sciences, Ghent University, Ghent University Hospital, De Pintelaan 185, 2P1, B-9000, Ghent, Belgium. Electronic address: sarah.vanhoutte@ugent.be.
Sarah
S
Vanhoutte
Department of Speech, Language and Hearing Sciences, Ghent University, Ghent University Hospital, De Pintelaan 185, 2P1, B-9000, Ghent, Belgium. Electronic address: marjan.cosyns@ugent.be.
Marjan
M
Cosyns
MEDISIP, Department of Electronics and Information Systems, Ghent University - iMINDS Medical IT Department, Ghent University Hospital 185, 5-Blok B, B-9000 Ghent, Belgium. Electronic address: pieter.vanmierlo@ugent.be.
Pieter
P
van Mierlo
Department of Neurology, Ghent University Hospital, De Pintelaan 185, 1K12A, B-Ghent, Belgium; Department of Physical Therapy and Motor Rehabilitation, Ghent University Hospital, De Pintelaan 185, B-Ghent, Belgium. Electronic address: katja.batens@ugent.be.
Katja
K
Batens
Department of Speech, Language and Hearing Sciences, Ghent University, Ghent University Hospital, De Pintelaan 185, 2P1, B-9000, Ghent, Belgium; Faculty of Education, Health and Social Work, University College Ghent, Keramiekstraat 80, B-9000 Ghent, Belgium. Electronic address: paul.corthals@ugent.be.
Paul
P
Corthals
Department of Speech, Language and Hearing Sciences, Ghent University, Ghent University Hospital, De Pintelaan 185, 2P1, B-9000, Ghent, Belgium; Department of Neurology, Ghent University Hospital, De Pintelaan 185, 1K12A, B-Ghent, Belgium. Electronic address: miet.deletter@ugent.be.
Miet
M
De Letter
Department of Speech, Language and Hearing Sciences, Ghent University, Ghent University Hospital, De Pintelaan 185, 2P1, B-9000, Ghent, Belgium. Electronic address: john.vanborsel@ugent.be.
John
J
Van Borsel
Department of Internal Medicine, Neurology, Ghent University, Ghent University Hospital, De Pintelaan 185, 1K12A, B-9000 Ghent, Belgium; Department of Neurology, Ghent University Hospital, De Pintelaan 185, 1K12A, B-Ghent, Belgium. Electronic address: patrick.santens@ugent.be.
Patrick
P
Santens
D000328:Adult; D003265:Contingent Negative Variation / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time; D013060:Speech / Q000502:physiology*; D013342:Stuttering / Q000503:physiopathology*; D055815:Young Adult
Basal ganglia; Compensation; Contingent negative variation; Motor preparation; Stuttering frequency; Stuttering severity