Disrupted white matter in language and motor tracts in developmental stuttering

Object Diffusion tensor (DT) imaging has been used to predict postoperative motor function in patients with supratentorial tumors. The authors sought to determine whether DT imaging and white matter tractography could detect axonal degeneration in patients with brainstem tumors. Methods A cross-sectional, retrospective study of 7 patients with brainstem tumors and 8 healthy volunteers was performed. The DT imaging data were normalized and regions of interest (ROIs) with the highest probability of sensory and motor connections were selected using the Talairach Atlas to identify the 3D millimetric coordinates of white matter tracts. An iterative process involving fractional anisotropy (FA), apparent diffusion coefficients (ADCs), and color maps was developed to precisely select ROIs in the bilateral sensory and motor tracts. The FA and ADC values were calculated for each ROI. Results The FA values of sensory and motor tracts significantly differed between the patient and healthy volunteer groups (p < 0.05), whereas no significant changes were found in the splenium or genu of the corpus callosum. The FA values were altered proximal and distal to the brainstem tumors with a bimodal peak of antegrade decreased FA involving second- and third-order sensory axons and retrograde decreased FA of motor axons. Conclusions This study demonstrates changes in diffusion properties of sensory and motor tracts consistent with degeneration to further characterize brainstem tumors in children, and the results warrant the planning of prospective trials. The rigorous methods the authors describe may provide valuable information when planning biopsies or debulking of unusual brainstem tumors, as well as improve prognostication of the possible functional tract recovery following therapy.

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Similarities in speech and white matter characteristics in idiopathic developmental stuttering and adult-onset stuttering

Journal of Neurolinguistics ◽

10.1016/j.jneuroling.2008.11.004 ◽

2010 ◽

Vol 23 (5) ◽

pp. 455-469 ◽

Cited By ~ 17

Author(s):

Soo-Eun Chang ◽

Anna Synnestvedt ◽

John Ostuni ◽

Christy L. Ludlow

Keyword(s):

White Matter ◽

Adult Onset ◽

Developmental Stuttering

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Regulatory Forum Opinion Piece*: Effective Sectioning of Spinal Cord during Regulatory-type Nonclinical Toxicity Studies

Toxicologic Pathology ◽

10.1177/0192623317720120 ◽

2017 ◽

Vol 45 (5) ◽

pp. 580-583 ◽

Cited By ~ 3

Author(s):

Brad Bolon

Keyword(s):

Spinal Cord ◽

Nervous System ◽

White Matter ◽

Best Practices ◽

Gray Matter ◽

Vertical Plane ◽

Toxicity Studies ◽

Regulatory Guidelines ◽

Motor Tracts ◽

Regulatory Type

Regulatory guidelines for nonclinical neurotoxicity testing require spinal cord evaluation but do not specify a trimming scheme. The Society of Toxicologic Pathology (STP) “best practices” for nervous system sampling during nonclinical general toxicity studies recommend that spinal cord be assessed in both longitudinal/oblique and transverse sections. This article defines possible longitudinal/oblique orientations, describes their benefits and challenges, and provides an expert recommendation regarding suitable trimming planes. Longitudinal parasagittal (LP) sections follow a vertical plane just lateral to the midline, revealing sensory and motor tracts but little gray matter. Longitudinal horizontal sections transect only sensory or motor tracts and variable quantities of gray matter. Oblique vertical (OV) sections angle across the spinal cord from side to side. Oblique transverse (OT) sections slant through from top (dorsal [posterior]) to bottom (ventral [anterior]). Compared to longitudinal planes, oblique orientations demonstrate considerably more gray matter and white matter. Current STP “best practices” explicitly recommend the LP and OV options; the OT orientation also will yield suitable sections while permitting assessment of anatomic symmetry. Selection among the LP, OT, and OV planes should be at the discretion of the study pathologist. The bilaterally symmetrical OT sections likely will be analyzed most easily by nonneuropathologists.

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Two cortical representations of voice control are differentially involved in speech fluency

Brain Communications ◽

10.1093/braincomms/fcaa232 ◽

2021 ◽

Author(s):

Nicole E Neef ◽

Annika Primaßin ◽

Alexander Wolff von Gudenberg ◽

Peter Dechent ◽

Heiner Christian Riedel ◽

...

Keyword(s):

White Matter ◽

Motor Cortex ◽

Cortical Network ◽

Speech Fluency ◽

Voice Control ◽

Persistent Developmental Stuttering ◽

Motor Cortical ◽

Structural Networks ◽

Developmental Stuttering ◽

Cortical Representations

Abstract Recent studies have identified two distinct cortical representations of voice control in humans, the ventral and the dorsal laryngeal motor cortex. Strikingly, while persistent developmental stuttering has been linked to a white matter deficit in the ventral laryngeal motor cortex, intensive fluency shaping intervention modulated the functional connectivity of the dorsal laryngeal motor cortical network. Currently, it is unknown whether the underlying structural network organization of these two laryngeal representations is distinct or differently shaped by stuttering intervention. Using probabilistic diffusion tractography in 22 individuals who stutter and participated in a fluency shaping intervention, in 18 individuals who stutter and did not participate in the intervention, and in 28 control participants, we here compare structural networks of the dorsal laryngeal motor cortex and the ventral laryngeal motor cortex and test intervention-related white matter changes. We show (i) that all participants have weaker ventral laryngeal motor cortex connections compared to the dorsal laryngeal motor cortex network, regardless of speech fluency, (ii) connections of the ventral laryngeal motor cortex were stronger in fluent speakers, (iii) the connectivity profile of the ventral laryngeal motor cortex predicted stuttering severity, (iv) but the ventral laryngeal motor cortex network is resistant to a fluency shaping intervention. Our findings substantiate a weaker structural organization of the ventral laryngeal motor cortical network in developmental stuttering and imply that assisted recovery supports neural compensation rather than normalization. Moreover, the resulting dissociation provides evidence for functionally segregated roles of the ventral laryngeal motor cortical and dorsal laryngeal motor cortical networks.

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P1.115 White matter hyperintensities in localized motor tracts are associated with delays in step initiation during a choice reaction step task

Parkinsonism & Related Disorders ◽

10.1016/s1353-8020(08)70212-8 ◽

2008 ◽

Vol 14 ◽

pp. S39

Author(s):

P.J. Sparto ◽

H.J. Aizenstein ◽

J.M. VanSwearingen ◽

C. Rosano ◽

S. Perera ◽

...

Keyword(s):

White Matter ◽

White Matter Hyperintensities ◽

Reaction Step ◽

Step Initiation ◽

Motor Tracts

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Fluent speech: neural basis of sensorimotor plasticity in developmental stuttering

10.1101/2020.07.27.219360 ◽

2020 ◽

Cited By ~ 1

Author(s):

Alexandra Korzeczek ◽

Annika Primassin ◽

Alexander Wolff von Gudenberg ◽

Peter Dechent ◽

Walter Paulus ◽

...

Keyword(s):

White Matter ◽

Fractional Anisotropy ◽

Inhibitory Control ◽

Sensorimotor Integration ◽

Network Activity ◽

Control Network ◽

Fluent Speech ◽

Developmental Stuttering ◽

The Impact ◽

Speech Motor

Developmental stuttering is a fluency disorder with anomalies in the neural speech motor system. Fluent speech requires multifunctional network formations. Currently, it is unclear which functional domain is targeted by speech fluency interventions. Here, we tested the impact of fluency-shaping on resting-state fMRI connectivity of the speech planning, articulatory convergence, sensorimotor integration, and inhibitory control network. Furthermore, we examined white matter metrics of major speech tracts. Improved fluency was accompanied by an increased synchronization within the sensorimotor integration network. Specifically, two connections were strengthened, left laryngeal motor cortex and right superior temporal gyrus showed increased connectivity with the left inferior frontal gyrus. The integration of the command-to-execution and auditory-motor pathway was strengthened. Since we investigated task-free brain activity, we assume that our findings are not biased to network activity involved in compensation. No alterations were found within white matter microstructure. But, brain-behavior relationships changed. We found a heightened negative correlation between stuttering severity and fractional anisotropy in the superior longitudinal fasciculus, and a heightened positive correlation between the psycho-social impact of stuttering and fractional anisotropy in the right frontal aslant tract. Taken together, structural and functional connectivity of the sensorimotor integration and inhibitory control network shape speech motor learning.

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Grey matter microstructural differences in developmental stuttering

10.31219/osf.io/ypq8s ◽

2021 ◽

Author(s):

Gabriel Cler ◽

Saloni Krishnan ◽

Daniel Papp ◽

Charlie E E Wiltshire ◽

Jennifer Chesters ◽

...

Keyword(s):

White Matter ◽

Brain Tissue ◽

Grey Matter ◽

Group Differences ◽

Significant Group ◽

Conventional Mri ◽

Cortical Motor ◽

Cortical Regions ◽

Developmental Stuttering ◽

New Evidence

Theoretical accounts of developmental stuttering implicate dysfunctional cortico-striatal-thalamo-cortical motor loops through the putamen, but empirical evidence of these proposed differences is currently limited. Conventional MRI data has been used in people who stutter to measure the size or volume of grey matter structures, cortical thickness, and diffusion properties of white matter fibre tracts. Quantitative mapping of brain tissue can reveal detailed maps of microstructural properties of brain tissue in both grey and white matter, but has not yet been assessed in people who stutter. Analysis of these quantitative maps in 41 people who stutter and 32 matched controls revealed significant group differences in maps of R2*, indicative of higher iron content in people who stutter than controls in left cortical regions important for speech motor control and the left putamen. Higher iron levels in brain tissue in people who stutter may be a marker of elevated dopamine levels or lysosomal dysfunction. This study represents the first use of these quantitative measures in developmental stuttering and provides new evidence of structural differences.

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