Language, gesture, and the developing brain.

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 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.