The effects of focal brain injury are investigated in the first stages of language development, during the passage from first words to grammar. Parent report and/or free speech data are reported for 53 infants and preschool children between 10 -44 months of age. All children had suffered a single, unilateral brain injury to the left or right hemisphere, incurred before six months of age (usually in the pre-or perinatal period). This is the period in which we should expect to see maximal plasticity, but it is also the period in which the initial specializations of particular cortical regions ought to be most evident. In direct contradiction of hypotheses based on the adult aphasia literature, results from 10 -17 months suggest that children with righthemisphere injuries are at greater risk for delays in word comprehension, and in the gestures that normally precede and accompany language onset. Although there were no differences between left-vs. right-hemisphere injury per se on expressive language, children whose lesions include the left temporal lobe did show significantly greater delays in expressive vocabulary and grammar throughout the period from 10 -44 months. There were no specific deficits associated with left frontal damage, but there was a significant effect of frontal lobe injury to either hemisphere in the period from 16 -31 months, when normal children usually show a burst in vocabulary and grammar. This bilateral effect of frontal damage is independent of motor impairment. Hence there are specific effects of lesion site in early language development, but they are not consistent with the lesion-syndrome correlations observed in adults with homologous injuries, nor with the literature on acquired lesions in older children. Results are used to argue against innate localization of linguistic representations, and in favor of an alternative view in which innate regional biases in style of information processing lead to familiar patterns of brain organization for language under normal conditions, while permitting alternative patterns to emerge in children with focal brain injury.
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FROM FIRST WORDS TO GRAMMAR IN CHILDREN WITH FOCAL BRAIN INJURYIn 1861, Paul Broca described a case of nonfluent aphasia with preserved comprehension, associated with damage to a region of left frontal cortex that now bears Broca's name. By 1874, Carl Wernicke had described a very different form of aphasia, a severe comprehension deficit with preserved fluency and melodic line (albeit with clear impairment of word retrieval). This syndrome was associated with damage to the posterior portion of the left temporal lobe, a region now referred to as Wernicke's area. The reliability and significance of these two complementary lesion-syndrome mappings have been called into question many times (Freud 1891(Freud /1953Goldstein, 1948;Head, 1963;Marie, 1906;Mohr et al., 1978), including recent studies using in vivo brain imaging which show that the classic lesion-syndrome correlations are violated at least 20% of the time (Basso, C...