Neural Language Processing in Adolescent First-Language Learners: Longitudinal Case Studies in American Sign Language.
Level 4 - case-series / case-control
Longitudinal case study of two individuals
PubMed 25410427 · doi:10.1093/cercor/bhu273
What was done
Anatomically constrained magnetoencephalography (aMEG) was used to longitudinally evaluate lexico-semantic processing in 2 deaf adolescents who had no sustained language input until age 14, when they became immersed in American Sign Language (ASL). Following an initial evaluation after 2 to 3 years of language exposure, participants were tested again after an additional 15 months of language experience to assess neural response localization and polarity to signed words.
What was found
The abstract reports no numerical values or statistical test metrics. Qualitatively, after 15 additional months of ASL immersion, neural response polarity remained atypical. Neural responses to less familiar signed words still exhibited atypical localization, whereas responses to highly familiar signed words became more concentrated in the canonical left perisylvian language network.
Why it matters
This study provides rare neuroimaging evidence that neural language organization remains plastic in adolescence, showing that experience can drive reorganization toward typical left perisylvian networks even after severe early language deprivation.
Limits
The study is limited to a sample size of 2 individuals, precluding population-level generalizations. The abstract provides purely qualitative descriptions of cortical localization and polarity without quantitative data, coordinates, or statistical effect sizes. Potential confounding factors such as individual cognitive differences and varying degrees of prior communication could not be broadly controlled.
Cited by
- partial If a child does not acquire language during the first several years of life, they can never acquire the fundamental concept of language.