Neural language processing in adolescent first-language learners.
Level 4 - case-series / case-control
Case series comparison (two rare case subjects evaluated against native and second-language control groups)
PubMed 23696277 · doi:10.1093/cercor/bht137
What was done
Researchers measured brain activity using anatomically constrained magnetoencephalography during American Sign Language (ASL) word processing in 2 congenitally deaf adolescents who had no sustained language input until approximately 14 years of age. Their neural activation patterns were compared against young deaf adults who acquired ASL from birth and hearing young adults learning ASL as a second language with similar exposure duration.
What was found
The abstract reports no numerical values. Qualitatively, recently learned signed words in the 2 late-learning adolescents primarily activated right superior parietal, anterior occipital, and dorsolateral prefrontal areas. This spatiotemporal pattern differed significantly from the left fronto-temporal pattern observed in native deaf signers and hearing second-language learners.
Why it matters
These findings provide direct evidence that the timing of early language experience during human development shapes the neural organization of language processing.
Limits
The sample size is extremely small (n=2 cases), reflecting the rarity of late first-language acquisition. The abstract does not report exact sample sizes for the control groups, quantitative effect sizes, statistical thresholds, or the behavioral proficiency levels of the participants.