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  Speech dynamics are coded in the left motor cortex in fluent speakers but not in adults who stutter

Neef, N., Hoang, T. N. L., Neef, A., Paulus, W., & Sommer, M. (2015). Speech dynamics are coded in the left motor cortex in fluent speakers but not in adults who stutter. Brain, 138(3), 712-725. doi:10.1093/brain/awu390.

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https://doi.org/10.1093/brain/awu390 (Publisher version)


Neef, Nicole1, 2, Author           
Hoang, T. N. Linh1, Author
Neef, Andreas3, Author
Paulus, Walter1, Author
Sommer, Martin1, Author
1Department of Clinical Neurophysiology, University Medical Center, Göttingen, Germany, ou_persistent22              
2Department Neuropsychology, MPI for Human Cognitive and Brain Sciences, Max Planck Society, ou_634551              
3Department of Nonlinear Dynamics, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany, ou_persistent22              


Free keywords: Motor control; Primary motor cortex; Transcranial magnetic stimulation; Motor evoked potentials; Stuttering
 Abstract: The precise excitability regulation of neuronal circuits in the primary motor cortex is central to the successful and fluent production of speech. Our question was whether the involuntary execution of undesirable movements, e.g. stuttering, is linked to an insufficient excitability tuning of neural populations in the orofacial region of the primary motor cortex. We determined the speech-related time course of excitability modulation in the left and right primary motor tongue representation. Thirteen fluent speakers (four females, nine males; aged 23–44) and 13 adults who stutter (four females, nine males, aged 21–55) were asked to build verbs with the verbal prefix ‘auf’. Single-pulse transcranial magnetic stimulation was applied over the primary motor cortex during the transition phase between a fixed labiodental articulatory configuration and immediately following articulatory configurations, at different latencies after transition onset. Bilateral electromyography was recorded from self-adhesive electrodes placed on the surface of the tongue. Off-line, we extracted the motor evoked potential amplitudes and normalized these amplitudes to the individual baseline excitability during the fixed configuration. Fluent speakers demonstrated a prominent left hemisphere increase of motor cortex excitability in the transition phase (P = 0.009). In contrast, the excitability of the right primary motor tongue representation was unchanged. Interestingly, adults afflicted with stuttering revealed a lack of left-hemisphere facilitation. Moreover, the magnitude of facilitation was negatively correlated with stuttering frequency. Although orofacial midline muscles are bilaterally innervated from corticobulbar projections of both hemispheres, our results indicate that speech motor plans are controlled primarily in the left primary speech motor cortex. This speech motor planning-related asymmetry towards the left orofacial motor cortex is missing in stuttering. Moreover, a negative correlation between the amount of facilitation and stuttering severity suggests that we discovered a main physiological principle of fluent speech production and its role in stuttering.


Language(s): eng - English
 Dates: 2014-08-012014-11-172015-01-152015-03-01
 Publication Status: Issued
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1093/brain/awu390
PMID: 25595146
PMC: PMC4408433
Other: Epub 2015
 Degree: -



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Project information

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Project name : -
Grant ID : -
Funding program : Dorothea Schlözer Fellowship Programme
Funding organization : University of Goettingen
Project name : -
Grant ID : NE 1841/1-1; SO 429/2-2; SO 429/4-1
Funding program : -
Funding organization : Deutsche Forschungsgemeinschaft (DFG)
Project name : -
Grant ID : -
Funding program : -
Funding organization : Rose Foundation for Communities and the Environment
Project name : -
Grant ID : 01GQ0810
Funding program : -
Funding organization : Bernstein Focus Neurotechnology

Source 1

Title: Brain
  Other : Brain
Source Genre: Journal
Publ. Info: London : Macmillan
Pages: - Volume / Issue: 138 (3) Sequence Number: - Start / End Page: 712 - 725 Identifier: ISSN: 0006-8950
CoNE: https://pure.mpg.de/cone/journals/resource/954925385135