fMRI identifies regional specialization of neural networks for reading in young children

Abstract

Background: fMRI allows mapping of neural networks underlying cognitive networks during development, but few studies have systematically examined children 7 and younger, in whom language networks may be more diffusely organized than in adults.

Objective: To identify neural networks during early reading consolidation in young children.

Methods: The authors studied 16 normal, right-handed, native English-speaking children with a mean age of 7.2 years (range 5.8 to 7.9) with fMRI reading paradigms adjusted for reading level. Data were acquired with the echoplanar imaging BOLD technique at 1.5 T. Group data were analyzed with statistical parametric mapping (SPM-99); individual data sets were analyzed with a region of interest approach from individual study t maps (t = 4). The number of activated pixels in brain regions was determined and an asymmetry index (AI) ([L-R]/[L+R]) calculated for each region.

Results: In group analysis the authors found prominent activation in left inferior temporal occipital junction and left fusiform gyrus (Brodmann area [BA] 37), middle temporal gyrus (BA 21, 22), middle frontal gyrus (BA 44, 45), and the supplementary motor area. Activation was strongly lateralized in middle frontal gyrus and Wernicke areas (AI 0.54, 0.62). Fourteen subjects had left-sided language lateralization, one was bilateral, and one had poor activation.

Conclusions: The neural networks that process reading are strongly lateralized and regionally specific by age 6 to 7 years. Neural networks in early readers are similar to those in adults.