In this presentation, I describe our research aimed at understanding the brain abnormalities that cause stuttering. We use MRI brain scans to measure how brain areas involved in producing speech (motor areas) and in monitoring speech (auditory areas) communicate with each other both functionally and structurally. Our findings of white matter disruptions (Watkins et al., 2009) and changes in coordinated motor and auditory activity during speech production in people who stutter (Watkins 2011) are consistent with the idea that the integration of sensory and motor signal is abnormal. MRI can also be used to see what is happening inside our mouths when we are speaking. We have developed new ways of using MRI to scan the vocal tract during fluent speech and during stuttering to show that movement of the articulators is more variable even during perceptually fluent speech production in people who stutter.
Recently, we used transcranial direct current stimulation (tDCS) in a double-blind randomised sham-controlled trial alongside fluency training in people who stutter. We found that 5-days of 1-mA anodal tDCS over the left inferior frontal cortex successfully reduced dysfluency by about one third and that these effects were still present 6 weeks after the end of the intervention (Chesters et al., 2018). MRI scans of brain activity during speech production before and after the intervention showed a significant increase in subcortical areas in the group that had anodal tDCS and successfully reduced their dysfluency relative to the group that had sham stimulation and showed no change in their fluency.
These studies suggest that developmental stuttering is caused by neural disruptions to systems involved in speech motor control. Brain stimulation coupled with speech fluency training now offers a realistic opportunity for improving fluency in adults who stutter for whom therapy options may be more limited or less effective than those available in childhood.
Katika maonyesho haya, ninaelezea utafiti wetu unaolenga kuelewa kasoro za ubongo zinazosababisha kugonga. Kwa kutumia MRI, watafiti wanaweza kupima jinsi sehemu za ubongo zinazohusika katika kuzalisha hotuba (sehemu za motor) na katika kufuatilia hotuba (sehemu za kusikia) zinavyowasiliana na kila mmoja kwa utendaji na muundo. Matokeo ya utafiti wetu wa usumbufu wa chembe nyeupe (Watkins et al., 2009) na mabadiliko katika shughuli za motor na auditory wakati wa uzalishaji wa hotuba katika watu ambao hutetemeka (Watkins, 2011) ni sawa na wazo kwamba ushirikiano wa ishara ya hisia na motor ni abnormal. MRI pia inaweza kutumika kuona nini kinachotokea ndani ya vinywa vyetu wakati tunazungumza. "Tumebuni njia mpya za kutumia MRI kuchunguza njia ya sauti wakati wa hotuba ya ufasaha na wakati wa kugongana, kuonyesha kwamba harakati za articulators ni tofauti zaidi hata wakati wa utengenezaji wa hotuba ya ufasaha kwa watu ambao wanagongana. """ Hivi karibuni, tulitumia Transcranial Direct Current Stimulation (TDCS) katika jaribio la kipofu la randomized na kudhibitiwa na udanganyifu pamoja na mafunzo ya ufasaha kwa watu ambao wanagongana. Kwa mfano, siku 5 za tDCS ya anode ya 1 mA juu ya cortex ya mbele ya kushoto ya chini ilifanya dysfluency kupungua kwa karibu theluthi moja na athari hizi zilikuwa bado zipo wiki 6 baada ya mwisho wa uingiliaji. Uchunguzi wa MRI wa shughuli za ubongo wakati wa utoaji wa hotuba kabla na baada ya uingiliaji ulionyesha ongezeko kubwa katika maeneo ya chini ya cortical katika kundi ambalo lilikuwa na TDCs ya anodine na kufanikiwa kupunguza dysfluency yao ikilinganishwa na kundi ambalo lilikuwa na stimulation ya sham na halikuonyesha mabadiliko katika fluency yao. Uchunguzi huo unaonyesha kwamba kugugumizi kwa sababu ya ukuzi husababishwa na kasoro za neva katika mifumo inayohusika katika kudhibiti usemi. Kuchochea ubongo pamoja na mafunzo ya ufasaha wa usemi sasa hutoa fursa halisi ya kuboresha ufasaha katika watu wazima ambao hutetemeka ambao chaguzi za matibabu zinaweza kuwa ndogo au zisizo na ufanisi kuliko zile zinazopatikana katika utoto.