返回Google圖書搜尋

Language Comprehension and Production in Normally Developing Children and Children with Language Impairment

其他書名	An FMRI Study
出版	University of California, San Diego, 2005
URL	http://books.google.com.hk/books?id=ysbQgAvSj8QC&hl=&source=gbs_api

註釋Evidence from brain imaging studies has demonstrated that changes in the behavioral profiles during late childhood are mirrored by continuing development and reorganization in brain morphology and physiology. However, very little is known about the development of functional organization underlying cognitive processes such as language. Even less is known about the physiological underpinnings of atypical language development, such as that seen with language impairment (LI), a condition defined as a delay or abnormality in expressive and/or receptive language skills in the absence of frank neurologic impairment, mental retardation, hearing loss, autism or social or emotional problems. Although a number of anatomical and functional abnormalities have been detected in the LI population, the functional neural patterns that underlie language processing in LI have not been described. In two sets of experiments, we used functional magnetic resonance imaging to explore brain activity in school-age children, with and without LI, and young adults, engaged in two tasks: (1) picture naming (PN) and (2) comprehension of sentences of increasing syntactic complexity (CSI). Two approaches were adopted to analyze the data: whole-brain group analysis with normalization to the Talairach template, and a region-of-interest (ROI) analysis, with each region traced on the individual subject's reconstructed cortical surface. Typically-developing children were as accurate as adults on picture naming, but significantly slower. On CSI, they were as fast as adults, but less accurate. Activation patterns were similar for the two groups, and compatible with the literature. However, numerous developmental and task-related differences in the activations were observed. For Picture Naming, children recruited frontal and parietal networks involved in lexical retrieval less than adults did. For CSI, we found more occipito-parietal activation in adults, and more frontal and temporal involvement for children. We suggest that interactions between maturational and strategic differences underlie developmental changes in functional patterns. Compared to typically-developing children, children with LI showed reduced but not divergent activation patterns, with consistent signal reduction in frontal, temporal, and parietal regions. Children with LI showed significantly more deactivations than controls in superior-frontal and middle-frontal gyri, inferior parietal lobule and precuneus. Our findings support a "resource limitation" account of LI.