Right-hemispheric organization of language following early left-sided brain lesions: functional MRI topography

Abstract

Left-hemispheric (LH) brain lesions acquired early in life can induce language organization in the undamaged right hemisphere (RH). This study addresses the anatomical correlates of language processing in the RH of such individuals. Five hemiparetic patients with left periventricular brain lesions of pre- and perinatal origin were included, in whom fMRI during a word generation task had yielded predominantly RH activation; five age- and sex-matched healthy right-handers served as controls. The patterns of activation in the RH of patients showed a striking similarity with the LH patterns of the normal controls, and voxel-wise comparison failed to detect significant differences. This demonstrates that in patients with early LH damage, RH recruitment for language occurs in brain areas homotopic to the LH regions involved in language processing under normal circumstances.