Structural connectivity of right frontal hyperactive areas scales with stuttering severity

Neef, Nicole E.; Anwander, Alfred; Bütfering, Christoph; Schmidt‐Samoa, Carsten; Friederici, Angela D.; Paulus, Walter; Sommer, Martin

doi:10.1093/brain/awx316

Cited by 94 publications

(133 citation statements)

References 111 publications

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“…Further studies reported that the disorganisation extended into ventral premotor cortex, bilaterally, and corresponded to abnormalities in functional activation of nearby grey matter in adolescents and young adults who stutter (Watkins, Smith, Davis, & Howell, ). In adults who stutter, the right hemisphere disruptions underlying ventral premotor tracts correspond to hyperactivity during imagined speech tasks in fMRI and correlate with stuttering severity (Neef et al, ).…”

Section: Introductionmentioning

confidence: 99%

Separation of trait and state in stuttering

Connally

Ward

Pliatsikas

et al. 2018

Human Brain Mapping

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Stuttering is a disorder in which the smooth flow of speech is interrupted. People who stutter show structural and functional abnormalities in the speech and motor system. It is unclear whether functional differences reflect general traits of the disorder or are specifically related to the dysfluent speech state. We used a hierarchical approach to separate state and trait effects within stuttering. We collected sparse‐sampled functional MRI during two overt speech tasks (sentence reading and picture description) in 17 people who stutter and 16 fluent controls. Separate analyses identified indicators of: (1) general traits of people who stutter; (2) frequency of dysfluent speech states in subgroups of people who stutter; and (3) the differences between fluent and dysfluent states in people who stutter. We found that reduced activation of left auditory cortex, inferior frontal cortex bilaterally, and medial cerebellum were general traits that distinguished fluent speech in people who stutter from that of controls. The stuttering subgroup with higher frequency of dysfluent states during scanning (n = 9) had reduced activation in the right subcortical grey matter, left temporo‐occipital cortex, the cingulate cortex, and medial parieto‐occipital cortex relative to the subgroup who were more fluent (n = 8). Finally, during dysfluent states relative to fluent ones, there was greater activation of inferior frontal and premotor cortex extending into the frontal operculum, bilaterally. The above differences were seen across both tasks. Subcortical state effects differed according to the task. Overall, our data emphasise the independence of trait and state effects in stuttering.

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Section: Introductionmentioning

confidence: 99%

Separation of trait and state in stuttering

Connally

Ward

Pliatsikas

et al. 2018

Human Brain Mapping

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“…Therefore, overactivation of this pathway results in increased global inhibition of motor systems, which in turn disrupts control of ongoing and succeeding motor programs for fluent speech . It must also be noted that a recent study revealed altered structural abnormalities in the white matter pathway connecting the right frontal regions with the pre‐SMA, as well as with subcortical structures . Therefore, it is possible that reduced stuttering by tDCS involving a cathode over RB in our study might be a consequence of indirect modulation of dysfunctional activity in the basal ganglia and/or right SMA, which are connected to the RB.…”

Section: Discussionmentioning

confidence: 75%

Online cathodal transcranial direct current stimulation to the right homologue of Broca's area improves speech fluency in people who stutter

Yada

Tomisato²,

Hashimoto

2018

Psychiatry Clin Neurosci

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Aim Previous functional imaging studies demonstrate that people who stutter (PWS) exhibit over‐ and under‐activation of Broca's and Wernicke's areas and their right hemisphere homologues when speaking. However, it is unclear whether this altered activation represents the neural cause of speech dysfluency or a secondary compensatory activation in PWS. To clarify the functional significance of the altered activation pattern in classic language areas and their right homologues, we examined whether the severity of stuttering was affected when the activation of these areas was modulated by brain stimulation. Methods While PWS read passages aloud, we applied transcranial direct current stimulation (tDCS) using electrode montages that included an anodal or cathodal electrode placed over one of the language areas and its right hemisphere homologue, with the second electrode placed over the contralateral supraorbital region. Each participant underwent both anodal and cathodal tDCS sessions, each of which included a sham stimulation. Effects of stimulation polarity and electrode location on the frequency of stuttering were analyzed. Results We observed a significant interaction between polarity and location on the frequency of stuttering. Follow‐up analyses revealed that a tDCS montage including the cathodal electrode over right Broca's area (RB) significantly reduced the frequency of stuttering. Conclusion The results indicated that stuttering severity was ameliorated when overactivation in RB was reduced by tDCS. This observation further suggests that speech dysfluency in PWS may be caused either by functional alteration in RB or by abnormal activation in speech motor control areas that are connected with RB.

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“…Some evidence indicates this is the case for the FAT's involvement in stuttering. Thus, a recent study by Neef and colleagues (Neef et al., ) showed that stronger structural connectivity of the right, but not left, FAT is associated with worse stuttering. They interpreted this as indication of hyperactivity of the network involved in global response suppression, which disrupts fluent speech that typically relies strongly on left perisylvian networks, supported by the left FAT and associated perisylvian pathways.…”

Section: Discussionmentioning

confidence: 95%

“…It has also been proposed that a primary deficit in ADHD is in fact one of inhibitory control (Barkley, 1997;Neely et al, 2017;Schachar, Mota, Logan, Tannock, & Klim, 2000). However, inhibitory control and more broadly defined executive function deficits are not a universal feature of ADHD (Nigg, Willcutt, Doyle, & Sonuga-Barke, 2005), and in fact there may be executive function subtypes of ADHD, with an inhibitory control dysfunction profile describing only one of the subtypes (Roberts, Martel, & Nigg, 2017 (Neef et al, 2018) showed that stronger structural connectivity of the right, but not left, FAT is associated with worse stuttering.…”

Section: The Role Of the Frontal Aslant Tract In Externalizing Behamentioning

confidence: 99%

Laterality of the frontal aslant tract (FAT) explains externalizing behaviors through its association with executive function

Garic

Broce

Graziano

et al. 2018

Developmental Science

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We investigated the development of a recently identified white matter pathway, the frontal aslant tract (FAT) and its association with executive function and externalizing behaviors in a sample of 129 neurotypical male and female human children ranging in age from 7 months to 19 years. We found that the FAT could be tracked in 92% of those children, and that the pathway showed age-related differences into adulthood. The change in white matter microstructure was very rapid until about 6 years, and then plateaued, only to show age-related increases again after the age of 11 years. In a subset of those children (5-18 years; n = 70), left laterality of the microstructural properties of the FAT was associated with greater attention problems as measured by the Child Behavior Checklist (CBCL). However, this relationship was fully mediated by higher executive dysfunction as measured by the Behavior Rating Inventory of Executive Function (BRIEF). This relationship was specific to the FAT-we found no relationship between laterality of a control pathway, or of the white matter of the brain in general, and attention and executive function. These findings suggest that the degree to which the developing brain favors a right lateralized structural dominance of the FAT is directly associated with executive function and attention. This novel finding provides a new potential structural biomarker to assess attention deficit hyperactivity disorder (ADHD) and associated executive dysfunction during development.

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Structural connectivity of right frontal hyperactive areas scales with stuttering severity

Cited by 94 publications

References 111 publications

Separation of trait and state in stuttering

Separation of trait and state in stuttering

Online cathodal transcranial direct current stimulation to the right homologue of Broca's area improves speech fluency in people who stutter

Laterality of the frontal aslant tract (FAT) explains externalizing behaviors through its association with executive function

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