title: Left-handedness and language lateralization in children.
abstract: 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 3T 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.
authors.affiliation: Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, OH, USA. Jerzy.Szaflarski@uc.edu
authors.forename: Jerzy P
authors.initials: JP
authors.lastname: Szaflarski
authors.forename: Akila
authors.initials: A
authors.lastname: Rajagopal
authors.forename: Mekibib
authors.initials: M
authors.lastname: Altaye
authors.forename: Anna W
authors.initials: AW
authors.lastname: Byars
authors.forename: Lisa
authors.initials: L
authors.lastname: Jacola
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Schmithorst
authors.forename: Mark B
authors.initials: MB
authors.lastname: Schapiro
authors.forename: Elena
authors.initials: E
authors.lastname: Plante
authors.forename: Scott K
authors.initials: SK
authors.lastname: Holland
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*