Language, Gesture, and the Developing Brain.pdf

Developmental Psychobiology, 40, 293-310, 2002 Language, Gesture, and the Developing Brain Elizabeth Bates and Frederic Dick Center for Research in Language and Department of Cognitive Science, University of California, San Diego ABSTRACT: Do language abilities develop in isolation? Are they mediated by a unique neural substrate, a mental organ devoted exclusively to language? Or is language built upon more general abilities, shared with other cognitive domains and mediated by common neural systems? Here we review results suggesting that language and gesture are “close family”, then turn to evidence that raises questions about how real those “family resemblances” are, summarizing dissociations from our developmental studies of several different child populations. We then examine both these veins of evidence in the light of some new findings from the adult neuroimaging literature and suggest a possible reinterpretation of these dissociations, as well as new directions for research with both children and adults. Keywords: language; gesture; language development; motor; parietal; imaging; fMRI; aphasia; context Do language abilities develop in isolation? Are they mediated by a unique neural substrate, a “mental organ” devoted exclusively to language? Or is language built upon more general abilities, shared with other cognitive domains and mediated by common neural systems? For many years, developmental scientists have addressed these questions by studying behavioral associations and dissociations between language and gesture across the period in which both systems are first acquired. Some compelling links have been observed, involving specific aspects of gesture that precede or accompany each of the major language milestones from 6 to 30 months of age. These behavioral results are compatible with an expan