Differential effects of unilateral lesions on language production in children and adults

We present the first direct comparison of language production in brain-inju red children and adults, using age-corrected z scores for multiple lexical and grammatical measures. Spontaneous speech samples were elicited in a str uctured biographical interview from 38 children (5-8 years of age), 24 with congenital left-hemisphere damage (LHD) and 14 with congenital right-hemis phere damage (RHD), compared with 38 age- and gender-matched controls, 21 a dults with unilateral injuries (14 LHD and 7 RHD), and 12 adult controls. A dults with LHD showed severe and contrasting profiles of impairment across all measures (including classic differences between fluent and nonfluent ap hasia). Adults with RHD (and three nonaphasic adults with LHD) showed fluen t but disinhibited and sometimes empty speech. None of these qualitative or quantitative deviations were observed in children with unilateral brain in jury. who were in the normal range for their age on all measures. There wer e no significant differences between children with LHD and RHD on any measu re. When LHD children were compared directly with LHD adults using age-corr ected z scores, the children scored far better than their adult counterpart s on structural measures. These results provide the first systematic confir mation of differential free-speech outcomes in children and adults and offe r strong evidence for neural and behavioral plasticity following early brai n damage. (C) 2001 Academic Press.