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Biol Psychiatry. 2014 Sep 1;76(5):397-404. doi: 10.1016/j.biopsych.2013.08.031. Epub 2013 Oct 11.

Disruption of functional networks in dyslexia: a whole-brain, data-driven analysis of connectivity.

Author information

  • 1Interdepartmental Neuroscience Program, Yale University, New Haven, Connecticut. Electronic address: emily.finn@yale.edu.
  • 2Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut.
  • 3Yale Center for Dyslexia and Creativity, Yale University, New Haven, Connecticut.
  • 4Department of Biomedical Engineering, Yale University, New Haven, Connecticut.
  • 5Department of Biomedical Engineering, Yale University, New Haven, Connecticut; Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut.
  • 6Department of Biomedical Engineering, Yale University, New Haven, Connecticut; Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut; Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut.

Abstract

BACKGROUND:

Functional connectivity analyses of functional magnetic resonance imaging data are a powerful tool for characterizing brain networks and how they are disrupted in neural disorders. However, many such analyses examine only one or a small number of a priori seed regions. Studies that consider the whole brain frequently rely on anatomic atlases to define network nodes, which might result in mixing distinct activation timecourses within a single node. Here, we improve upon previous methods by using a data-driven brain parcellation to compare connectivity profiles of dyslexic (DYS) versus nonimpaired (NI) readers in the first whole-brain functional connectivity analysis of dyslexia.

METHODS:

Whole-brain connectivity was assessed in children (n = 75; 43 NI, 32 DYS) and adult (n = 104; 64 NI, 40 DYS) readers.

RESULTS:

Compared to NI readers, DYS readers showed divergent connectivity within the visual pathway and between visual association areas and prefrontal attention areas; increased right-hemisphere connectivity; reduced connectivity in the visual word-form area (part of the left fusiform gyrus specialized for printed words); and persistent connectivity to anterior language regions around the inferior frontal gyrus.

CONCLUSIONS:

Together, findings suggest that NI readers are better able to integrate visual information and modulate their attention to visual stimuli, allowing them to recognize words on the basis of their visual properties, whereas DYS readers recruit altered reading circuits and rely on laborious phonology-based "sounding out" strategies into adulthood. These results deepen our understanding of the neural basis of dyslexia and highlight the importance of synchrony between diverse brain regions for successful reading.

© 2013 Society of Biological Psychiatry Published by Society of Biological Psychiatry All rights reserved.

KEYWORDS:

Brain networks; dyslexia; fMRI; functional connectivity; reading; visual attention

PMID:
24124929
[PubMed - in process]
PMCID:
PMC3984371
[Available on 2015/9/1]
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