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Title: Using tDCS to improve speech processes in typical speakers and people who stutter
Author: Bashir, Naheem
ISNI:       0000 0004 7970 6160
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available