title: Neural language processing in adolescent first-language learners.
abstract: The relation between the timing of language input and development of neural organization for language processing in adulthood has been difficult to tease apart because language is ubiquitous in the environment of nearly all infants. However, within the congenitally deaf population are individuals who do not experience language until after early childhood. Here, we investigated the neural underpinnings of American Sign Language (ASL) in 2 adolescents who had no sustained language input until they were approximately 14 years old. Using anatomically constrained magnetoencephalography, we found that recently learned signed words mainly activated right superior parietal, anterior occipital, and dorsolateral prefrontal areas in these 2 individuals. This spatiotemporal activity pattern was significantly different from the left fronto-temporal pattern observed in young deaf adults who acquired ASL from birth, and from that of hearing young adults learning ASL as a second language for a similar length of time as the cases. These results provide direct evidence that the timing of language experience over human development affects the organization of neural language processing.
authors.affiliation: Department of Linguistics, Multimodal Imaging Laboratory.
authors.forename: Naja
authors.initials: N
authors.lastname: Ferjan Ramirez
authors.affiliation: Multimodal Imaging Laboratory, Department of Radiology.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Leonard
authors.affiliation: Multimodal Imaging Laboratory, Department of Radiology.
authors.forename: Christina
authors.initials: C
authors.lastname: Torres
authors.affiliation: Department of Linguistics.
authors.forename: Marla
authors.initials: M
authors.lastname: Hatrak
authors.affiliation: Multimodal Imaging Laboratory, Department of Radiology, Department of Neurosciences, Kavli Institute for Brain and Mind, University of California, San Diego, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Halgren
authors.affiliation: Department of Linguistics.
authors.forename: Rachel I
authors.initials: RI
authors.lastname: Mayberry
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002540:Cerebral Cortex / Q000502:physiology*; D003423:Critical Period, Psychological; D003638:Deafness; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007804:Language Development; D007858:Learning / Q000502:physiology; D015225:Magnetoencephalography; D008297:Male; D012660:Semantics; D012813:Sign Language; D055815:Young Adult
keywords: age of acquisition; anatomically constrained magnetoencephalography; critical period; language processing; sign language