Temporal-callosal pathway diffusivity predicts phonological skills in children

doi:10.1073/pnas.0608961104

Temporal-callosal pathway diffusivity predicts phonological skills in children

Stanford Institute for Reading and Learning, and Department of Psychology, Stanford University, Stanford, CA 94305

Edited by Marcus E. Raichle, Washington University School of Medicine, St. Louis, MO, and approved April 3, 2007 (received for review October 10, 2006)

Abstract

The development of skilled reading requires efficient communication between distributed brain regions. By using diffusion tensor imaging, we assessed the interhemispheric connections in a group of children with a wide range of reading abilities. We segmented the callosal fibers into regions based on their likely cortical projection zones, and we measured diffusion properties in these segmented regions. Phonological awareness (a key factor in reading acquisition) was positively correlated with diffusivity perpendicular to the main axis of the callosal fibers that connect the temporal lobes. These results could be explained by several physiological properties. For example, good readers may have fewer but larger axons connecting left and right temporal lobes, or their axon membranes in these regions may be more permeable than the membranes of poor readers. These measurements are consistent with previous work suggesting that good readers have reduced interhemispheric connectivity and are better at processing rapidly changing visual and auditory stimuli.

Footnotes

*To whom correspondence should be addressed. E-mail: bobd{at}stanford.edu
Author contributions: R.F.D., M.B.-S., G.K.D., and B.A.W. designed research; R.F.D., M.B.-S., G.K.D., and A.H. performed research; R.F.D. contributed new reagents/analytic tools; R.F.D., A.H., and G.R.F. analyzed data; and R.F.D., M.B.-S., and B.A.W. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Abbreviations:

DTI,

diffusion tensor imaging;

FA,

fractional anisotropy;

ROI,

region of interest;

MD,

mean diffusivity;

ADHD,

attention deficit/hyperactivity disorder;

PDD,

principal diffusion direction;

AC,

anterior commissure;

PC,

posterior commissure.