title: The frontal aslant tract underlies speech fluency in persistent developmental stuttering.
abstract: The frontal aslant tract (FAT) is a pathway that connects the inferior frontal gyrus with the supplementary motor area (SMA) and pre-SMA. The FAT was recently identified and introduced as part of a "motor stream" that plays an important role in speech production. In this study, we use diffusion imaging to examine the hypothesis that the FAT underlies speech fluency, by studying its properties in individuals with persistent developmental stuttering, a speech disorder that disrupts the production of fluent speech. We use tractography to quantify the volume and diffusion properties of the FAT in a group of adults who stutter (AWS) and fluent controls. Additionally, we use tractography to extract these measures from the corticospinal tract (CST), a well-known component of the motor system. We compute diffusion measures in multiple points along the tracts, and examine the correlation between these diffusion measures and behavioral measures of speech fluency. Our data show increased mean diffusivity in bilateral FAT of AWS compared with controls. In addition, the results show regions within the left FAT and the left CST where diffusivity values are increased in AWS compared with controls. Last, we report that in AWS, diffusivity values measured within sub-regions of the left FAT negatively correlate with speech fluency. Our findings are the first to relate the FAT with fluent speech production in stuttering, thus adding to the current knowledge of the functional role that this tract plays in speech production and to the literature of the etiology of persistent developmental stuttering.
authors.affiliation: The Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, 5290002, Ramat-Gan, Israel. vered.kronfeld@gmail.com.
authors.forename: Vered
authors.initials: V
authors.lastname: Kronfeld-Duenias
authors.affiliation: Department of Communication Disorders, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Ofer
authors.initials: O
authors.lastname: Amir
authors.affiliation: Department of Communication Disorders, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Ruth
authors.initials: R
authors.lastname: Ezrati-Vinacour
authors.affiliation: The Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, 5290002, Ramat-Gan, Israel.
authors.forename: Oren
authors.initials: O
authors.lastname: Civier
authors.affiliation: The Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, 5290002, Ramat-Gan, Israel. michalb@mail.biu.ac.il.|Department of English Literature and Linguistics, Bar-Ilan University, 5290002, Ramat-Gan, Israel. michalb@mail.biu.ac.il.
authors.forename: Michal
authors.initials: M
authors.lastname: Ben-Shachar
mesh_terms: D000162:Acoustics; D000328:Adult; D001931:Brain Mapping / Q000379:methods; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D009434:Neural Pathways / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000503:physiopathology*; D011712:Pyramidal Tracts / Q000503:physiopathology; D013018:Sound Spectrography; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013068:Speech Production Measurement; D013342:Stuttering / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D014741:Video Recording; D055815:Young Adult
keywords: Corticospinal tract; Diffusion imaging; Fiber tracking; Fluency; Frontal aslant tract; White matter