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. 2016 Oct;161:45-56.
doi: 10.1016/j.bandl.2015.07.006. Epub 2015 Aug 22.

White Matter Integrity of Cerebellar-Cortical Tracts in Reading Impaired Children: A Probabilistic Tractography Study

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Free PMC article

White Matter Integrity of Cerebellar-Cortical Tracts in Reading Impaired Children: A Probabilistic Tractography Study

Vindia G Fernandez et al. Brain Lang. .
Free PMC article

Abstract

Little is known about the white matter integrity of cerebellar-cortical pathways in individuals with dyslexia. Building on previous findings of decreased volume in the anterior lobe of the cerebellum, we utilized novel cerebellar segmentation procedures and probabilistic tractography to examine tracts that connect the anterior lobe of the cerebellum and cortical regions typically associated with reading: the temporoparietal (TP), occipitotemporal (OT), and inferior frontal (IF) regions. The sample included 29 reading impaired children and 27 typical readers. We found greater fractional anisotropy (FA) for the poor readers in tracts connecting the cerebellum with TP and IF regions relative to typical readers. In the OT region, FA was greater for the older poor readers, but smaller for the younger ones. This study provides evidence for discrete, regionally-bound functions of the cerebellum and suggests that projections from the anterior cerebellum appear to have a regulatory effect on cortical pathways important for reading.

Keywords: Cerebellum; Children; DTI; Dyslexia; Reading; Tractography.

Figures

Fig. 1
Fig. 1
Cortical regions of interest. Left hemisphere inflated surface view is displayed using Tksurfer in Freesurfer v5.3.0. The green and red lines are indices of curvature overlaid on the inflated surface and are helpful for referencing gyri (green) and sulci (red). Each cortical gray matter label used in the probabilistic tractography analyses are color-coded overlays on the inflated surface. Blue = inferior frontal gyrus;pink = temporoparietal; yellow = occipitotemporal.
Fig. 2
Fig. 2
Example of merging multi-model imaging data for probabilistic tractography. (A) Cortical gray matter used in tractography are displayed in FSL’s 3D viewer in a color-coded fashion (green = RAC mask; yellow = right OT mask; pink = right TP mask; blue = right IFG mask). (B) Cortical GM mask of left IFG from Freesurfer is co-registered with DTI ProbtrackX output for evaluating structural connectivity between RAC and Left IFG (red). (C) Cortical GM mask of left OT mask from Freesurfer is co-registered with DTI ProbtrackX output for evaluating structural connectivity between RAC and left OT (green). (D) Cortical GM mask of left TP mask from Freesurfer is co-registered with DTI ProbtrackX output for evaluating structural connectivity between RAC and left TP (blue).
Fig. 3
Fig. 3
Example of pathway generated by ProbtrackX output. 3D display showing trajectory of ProbtrackX output (red) between RAC (blue seed mask) and LIF (green target mask) in high resolution T1-space for a representative study participant.
Fig. 4
Fig. 4
FA scalar maps of a poor reader and typical reader. FA scalar map (heat scale) demonstrating FA values in pathway resulting from probabilistic tractography between RAC (seed mask) and LIF (purple target mask) in a poor reader (A) and a typical reader (B).
Fig. 5
Fig. 5
Interactions between age and DTI metrics in anterior cerebellar tracts by terminal cortical region.
Fig. 6
Fig. 6
(a–c) Group differences in DTI metrics of cerebellar tracts by terminal cortical region.
Fig. 7
Fig. 7
(a and b) Hemisphere effects for FA and AD.

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