Cerebral Bases of Speech Perception in Infants
Thursday, 4:30 PM - 6:15 PM
Hynes CC 203

Speaker: G. Dehaene-Lambertz, INSERM U562, Orsay, France Chair: Janet Werker, University of British Columbia

Biographical Sketch
Originally qualified as a paediatrician, Ghislaine Dehaene-Lambertz is a full-time associate researcher at Institut national de la santé et de la recherche médicale ( INSERM) U562, Paris, France, where she investigates the development of cognitive functions with brain imaging techniques. She published pioneering work using high-density event-related potentials (Nature 1994), functional resonance magnetic imaging (Science 2002) or optical topography (PNAS 2003) to study language acquisition. The goal of her research is to study the brain functional organization at the beginning of life in order to understand how complex cognitive functions, such as language, music, mathematics, etc… emerge in the human brain. Her approach is to examine the primitive functions that are accessible to the human brain to process the external word at the beginning of life, then to study how initial biases in brain organization could be shaped by the human environment to give rise to the mature state.

Abstract
Language is one of the main cognitive characteristics of the human species and relies in adults on precise and specialized networks, located primarily in the left hemisphere, around the sylvian fissure. Although different human languages use different sounds, words and syntax, children acquire their native language without difficulties following the same developmental path. What in the organization of the human brain favors the development of language in our species? Do we develop language because we possess a larger brain endowed with powerful general learning mechanisms, or because we possess a specific neuronal organization particularly efficient at extracting meaning from speech? Thanks to the development of brain imaging, we can now study early functional brain organization and understand what are the biological biases that favour speech learning in infants. Results obtained during the first months of life with functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs) show that the neuronal networks engaged when infants listen to speech are close to those described in adults and comprise multiple brain areas that are involved in phonological representations, lexical storing, memory and attention in adults. Furthermore, as in adults a significant asymmetry favoring the left hemisphere is observed at the level of the planum temporale. These similarities between preverbal infants and adults expert in their native language, suggest a continuity in functional and anatomical structures that underlie language processing. Language development appears thus to be based on a progressive differentiation of pre-constrained networks that are shaped by the native language.