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Using tDCS to improve speech processes in typical speakers and people who stutter

Bashir, Naheem; (2019) Using tDCS to improve speech processes in typical speakers and people who stutter. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Stuttering is a speech disorder for which treatment options are limited. Brain stimulation methods such as tDCS used as an adjunct to treatments enhance positive effects of intervention. This thesis addressed whether tDCS applied to the left inferior frontal gyrus would improve speech processes in typical speakers (TS) and people who stutter (PWS). Study 1.1 with TS showed that tDCS resulted in enhanced performance (reduction in speech reaction times) for three, but not one, syllable words in a picture naming task. Such interaction between stimuli complexity and tDCS was explored in Study 1.2. A picturenaming task was used with three syllable stimuli. Primes either facilitated the speech plan (low complexity) or required speech-plan reformulation. When anodal tDCS was applied, incongruent trials alone were significantly quicker than sham trials, replicating the effect of difficulty. Study 3 with TS applied tDCS whilst participants repeated tongue twisters. Anodal tDCS resulted in significantly faster tongue twister completion times compared to sham or cathodal stimulation. The studies with TS indicated that tDCS improves speech processes, particularly when task complexity is high. Study 4, applied tDCS to PWS alongside a challenging intervention known to reduce stuttering. There were reductions in stuttering during conversation that trended towards significance (sample size was small). Finally, we examined inferior frontal gyrus neural activity in PWS and TS whilst conversing socially or to a recording. The left inferior frontal gyrus showed significant and unique responses during face-to-face conversation compared to audio conversation. Findings indicated that the left inferior frontal gyrus is differentially involved when PWS communicate in different styles. This thesis demonstrated that tDCS is a promising adjunct for improving speech production processes in TS and PWS to use with challenging tasks and interventions. Further research is required to understand mechanisms of effect and to further refine effects for this promising approach.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Using tDCS to improve speech processes in typical speakers and people who stutter
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2019. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/ 4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10073581
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