The association between developmental trajectories of language-related white matter fiber pathways from 6 to 24 months of age and individual differences in language production at 24 months of age was investigated. The splenium of the corpus callosum, a fiber pathway projecting through the posterior hub of the default mode network to occipital visual areas, was examined as well as pathways implicated in language function in the mature brain, including the arcuate fasciculi, uncinate fasciculi, and inferior longitudinal fasciculi. The hypothesis that the development of neural circuitry supporting domain-general orienting skills would relate to later language performance was tested in a large sample of typically developing infants. The present study included 77 infants with diffusion weighted MRI scans at 6, 12 and 24 months and language assessment at 24 months. The rate of change in splenium development varied significantly as a function of language production, such that children with greater change in fractional anisotropy (FA) from 6 to 24 months produced more words at 24 months. Contrary to findings from older children and adults, significant associations between language production and FA in the arcuate, uncinate, or left inferior longitudinal fasciculi were not observed. The current study highlights the importance of tracing brain development trajectories from infancy to fully elucidate emerging brain–behavior associations while also emphasizing the role of the splenium as a key node in the structural network that supports the acquisition of spoken language.
Bibliographical noteFunding Information:
The authors thank the IBIS children and their families for their ongoing participation in this longitudinal study. This research was supported by grants awarded to Dr Piven from NIH/National Institute of Child Health and Development (NICHD) (Autism Center of Excellence, R01 HD055741 and HD055741-S1; Intellectual and Developmental Disabilities Research Center, P30 HD03110 and T32 HD40127), Autism Speaks, and the Simons Foundation (SFARI Grant 140209). Dr Swanson was supported by a National Research Service Award (T32-HD40127) from NICHD. Dr Wolff was supported by a grant from the National Institute of Mental Health (K01-101653). Further support was provided by the National Alliance for Medical Image Computing, U54 EB005149 (PI Ron Kikinis) and NIH/National Institute of Mental Health and National Institute on Drug Abuse P01 DA022446 (PI Josephine Johns).
© 2015 John Wiley & Sons Ltd