Speech rate association with cerebellar white-matter diffusivity in adults with persistent developmental stuttering

Sivan Jossinger, Vered Kronfeld-Duenias, Avital Zislis, Ofer Amir, Michal Ben-Shachar

Research output: Contribution to journalArticlepeer-review

Abstract

Speech rate is a basic characteristic of language production, which affects the speaker’s intelligibility and communication efficiency. Various speech disorders, including persistent developmental stuttering, present altered speech rate. Specifically, adults who stutter (AWS) typically exhibit a slower speech rate compared to fluent speakers. Evidence from imaging studies suggests that the cerebellum contributes to the paced production of speech. People who stutter show structural and functional abnormalities in the cerebellum. However, the involvement of the cerebellar pathways in controlling speech rate remains unexplored. Here, we assess the association of the cerebellar peduncles with speech rate in AWS and control speakers. Diffusion MRI and speech-rate data were collected in 42 participants (23 AWS, 19 controls). We used deterministic tractography with Automatic Fiber segmentation and Quantification (AFQ) to identify the superior, middle, and inferior cerebellar peduncles (SCP, MCP, ICP) bilaterally, and quantified fractional anisotropy (FA) and mean diffusivity (MD) along each tract. No significant differences were observed between AWS and controls in the diffusivity values of the cerebellar peduncles. However, AWS demonstrated a significant negative association between speech rate and FA within the left ICP, a major cerebellar pathway that transmits sensory feedback signals from the olivary nucleus into the cerebellum. The involvement of the ICP in controlling speech production in AWS is compatible with the view that stuttering stems from hyperactive speech monitoring, where even minor deviations from the speech plan are considered as errors. In conclusion, our findings suggest a plausible neural mechanism for speech rate reduction observed in AWS.

Original languageEnglish
Pages (from-to)801-816
Number of pages16
JournalBrain Structure and Function
Volume226
Issue number3
DOIs
StatePublished - Apr 2021

Keywords

  • Articulation rate
  • Cerebellum
  • DTI
  • Speech-rate
  • Stuttering
  • Tractography

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