文摘
This fMRI study investigated the development of language lateralization in left- and righthanded children between 5 and 18 years of age. Twenty-seven left-handed children (17 boys, 10 girls) and 54 age- and gender-matched right-handed children were included. We used functional MRI at 3 T and a verb generation task to measure hemispheric language dominance based on either frontal or temporo-parietal regions of interest (ROIs) defined for the entire group and applied on an individual basis. Based on the frontal ROI, in the left-handed group, 23 participants (85 % ) demonstrated left-hemispheric language lateralization, 3 (11 % ) demonstrated symmetric activation, and 1 (4 % ) demonstrated right-hemispheric lateralization. In contrast, 50 (93 % ) of the right-handed children showed left-hemispheric lateralization and 3 (6 % ) demonstrated a symmetric activation pattern, while one (2 % ) demonstrated a right-hemispheric lateralization. The corresponding values for the temporo-parietal ROI for the left-handed children were 18 (67 % ) left-dominant, 6 (22 % ) symmetric, 3 (11 % ) right-dominant and for the right-handed children 49 (91 % ), 4 (7 % ), 1 (2 % ), respectively. Left-hemispheric language lateralization increased with age in both groups but somewhat different lateralization trajectories were observed in girls when compared to boys. The incidence of atypical language lateralization in left-handed children in this study was similar to that reported in adults. We also found similar rates of increase in left-hemispheric language lateralization with age between groups (i.e., independent of handedness) indicating the presence of similar mechanisms for language lateralization in left- and right-handed children.
