title: Disconnection of speech-relevant brain areas in persistent developmental stuttering.
abstract: BACKGROUND
  The neuronal basis of persistent developmental stuttering is unknown. The disorder could be related to a reduced left hemisphere dominance, which functional neuroimaging data suggest might lead to right hemispheric motor and premotor overactivation. Alternatively, the core deficit underlying stuttering might be located in the speech-dominant left hemisphere. Furthermore, magnetoencephalography study results show profound timing disturbances between areas involved in language preparation and execution in the left hemisphere, suggesting that persistent developmental stuttering might be related to impaired neuronal communication, possibly caused by a disruption of white matter fibre tracts. We aimed to establish whether disconnection between speech-related cortical areas was the structural basis of persistent developmental stuttering.
  
  
  METHODS
  We analysed the speech of 15 people with persistent developmental stuttering and 15 closely matched controls for the percentage of syllables stuttered. We used diffusion tensor imaging to assess participants' brain tissue structure, and used and two-sample t test to compare diffusion characteristics between groups.
  
  
  RESULTS
  Diffusion characteristics of the group with persistent developmental stuttering and controls differed significantly immediately below the laryngeal and tongue representation in the left sensorimotor cortex (mean difference in fractional anisotropy 0.04 [95% CI 0.03-0.05]).
  
  
  CONCLUSIONS
  Our findings show that persistent developmental stuttering results from disturbed timing of activation in speech-relevant brain areas, and suggest that right hemisphere overactivation merely reflects a compensatory mechanism, analogous to right hemisphere activation in aphasia.
authors.affiliation: NeuroImage Nord, Department of Neurology, University of Hamburg, Hamburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Sommer
authors.forename: Martin A
authors.initials: MA
authors.lastname: Koch
authors.forename: Walter
authors.initials: W
authors.lastname: Paulus
authors.forename: Cornelius
authors.initials: C
authors.lastname: Weiller
authors.forename: Christian
authors.initials: C
authors.lastname: Büchel
mesh_terms: D000328:Adult; D001921:Brain / Q000002:abnormalities*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012720:Severity of Illness Index; D013342:Stuttering / Q000145:classification / Q000503:physiopathology*