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Cereb Cortex. 2011 Feb;21(2):254-61. doi: 10.1093/cercor/bhq082. Epub 2010 May 23.

Optical brain imaging reveals general auditory and language-specific processing in early infant development.

Author information

1
Laboratoire de Sciences Cognitives et Psycholinguistique, ENS-DEC-EHESS-CNRS, Paris 75005, France. myasuyo@bea.hi-ho.ne.jp

Abstract

This study uses near-infrared spectroscopy in young infants in order to elucidate the nature of functional cerebral processing for speech. Previous imaging studies of infants' speech perception revealed left-lateralized responses to native language. However, it is unclear if these activations were due to language per se rather than to some low-level acoustic correlate of spoken language. Here we compare native (L1) and non-native (L2) languages with 3 different nonspeech conditions including emotional voices, monkey calls, and phase scrambled sounds that provide more stringent controls. Hemodynamic responses to these stimuli were measured in the temporal areas of Japanese 4 month-olds. The results show clear left-lateralized responses to speech, prominently to L1, as opposed to various activation patterns in the nonspeech conditions. Furthermore, implementing a new analysis method designed for infants, we discovered a slower hemodynamic time course in awake infants. Our results are largely explained by signal-driven auditory processing. However, stronger activations to L1 than to L2 indicate a language-specific neural factor that modulates these responses. This study is the first to discover a significantly higher sensitivity to L1 in 4 month-olds and reveals a neural precursor of the functional specialization for the higher cognitive network.

PMID:
20497946
PMCID:
PMC3020578
DOI:
10.1093/cercor/bhq082
[Indexed for MEDLINE]
Free PMC Article

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