title: Neural Language Processing in Adolescent First-Language Learners: Longitudinal Case Studies in American Sign Language.
abstract: One key question in neurolinguistics is the extent to which the neural processing system for language requires linguistic experience during early life to develop fully. We conducted a longitudinal anatomically constrained magnetoencephalography (aMEG) analysis of lexico-semantic processing in 2 deaf adolescents who had no sustained language input until 14 years of age, when they became fully immersed in American Sign Language. After 2 to 3 years of language, the adolescents' neural responses to signed words were highly atypical, localizing mainly to right dorsal frontoparietal regions and often responding more strongly to semantically primed words (Ferjan Ramirez N, Leonard MK, Torres C, Hatrak M, Halgren E, Mayberry RI. 2014. Neural language processing in adolescent first-language learners. Cereb Cortex. 24 (10): 2772-2783). Here, we show that after an additional 15 months of language experience, the adolescents' neural responses remained atypical in terms of polarity. While their responses to less familiar signed words still showed atypical localization patterns, the localization of responses to highly familiar signed words became more concentrated in the left perisylvian language network. Our findings suggest that the timing of language experience affects the organization of neural language processing; however, even in adolescence, language representation in the human brain continues to evolve with experience.
authors.affiliation: Department of Linguistics, Multimodal Imaging Laboratory, Institute for Learning and Brain Sciences, University of Washington, Seattle, WA 98195, USA.
authors.forename: Naja
authors.initials: N
authors.lastname: Ferjan Ramirez
authors.affiliation: Multimodal Imaging Laboratory, Department of Radiology, Department of Neurological Surgery, University of California, San Francisco, CA 94158, USA.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Leonard
authors.affiliation: Department of Linguistics, Multimodal Imaging Laboratory.
authors.forename: Tristan S
authors.initials: TS
authors.lastname: Davenport
authors.affiliation: Multimodal Imaging Laboratory.
authors.forename: Christina
authors.initials: C
authors.lastname: Torres
authors.affiliation: Multimodal Imaging Laboratory, Department of Radiology, Department of Neuroscience and Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, CA 92093, 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; D001921:Brain / Q000254:growth & development* / Q000503:physiopathology*; D001931:Brain Mapping; D003423:Critical Period, Psychological; D003638:Deafness / Q000503:physiopathology* / Q000523:psychology / Q000534:rehabilitation; D005260:Female; D006801:Humans; D007804:Language Development; D008137:Longitudinal Studies; D015225:Magnetoencephalography; D008297:Male; D060865:Repetition Priming / Q000502:physiology; D012660:Semantics; D012813:Sign Language; D014796:Visual Perception / Q000502:physiology
keywords: age of acquisition; anatomically constrained magnetoencephalography; critical period; plasticity; sign language