C Weber-Fox | PubMed Health

PubMed2001

Neural systems for sentence processing in stuttering.

The role of neurolinguistic factors in stuttering was investigated by determining whether individuals who stutter display atypical neural functions for language processing, even with no speech production demands. Event-related brain potentials (ERPs) were obtained while 9 individuals who stutter (IWS) and 9 normally fluent speakers (NS) read sentences silently. The ERPs were elicited by: (a) closed-class words that provide structural or grammatical information, (b) open-class words that convey referential meaning, and (c) semantic anomalies (violations in semantic expectation). In standardized tests, adult IWS displayed similar grammatical and lexical abilities in both comprehension and production tasks compared to their matched, normally fluent peers. Yet the ERPs elicited in IWS for linguistic processing tasks revealed differences in functional brain organization. The ERPs elicited in IWS were characterized by reduced negative amplitudes for closed-class words (N280), open-class words (N350), and semantic anomalies (N400) in a temporal window of approximately 200-450 ms after word onsets. The overall pattern of results indicates that alterations in processing for IWS are related to neural functions that are common to word classes and perhaps involve shared, underlying processes for lexical access.

Adolescent↗

PubMed2001

Sensitive periods differentiate processing of open- and closed-class words: an ERP study of bilinguals.

The goal of this study was to test the hypothesis that neural processes for language are heterogeneous in their adaptations to maturation and experience. This study examined whether the neural processes for open- and closed-class words are differentially affected by delays in second-language immersion. In English, open-class words primarily convey referential meaning, whereas closed-class words are primarily related to grammatical information in sentence processing. Previous studies indicate that event-related brain potentials (ERPs) elicited by these word classes display nonidentical distributions and latencies, show different developmental time courses, and are differentially affected by early language experience in Deaf individuals. In this study, ERPs were recorded from 10 monolingual English speakers and 53 Chinese-English bilingual speakers who were grouped according to their age of immersion in English: 1-3, 4-6, 7-10, 11-13, and >15 years of age. Closed-class words elicited an N280 that was largest over left anterior electrode sites for all groups. However, the peak latency was later (>35 ms) in bilingual speakers immersed in English after 7 years of age. In contrast, the latencies and distributions of the N350 elicited by open-class words were similar in all groups. In addition, the N400, elicited by semantic anomalies (open-class words that violated semantic expectation), displayed increased peak latencies for only the later-learning bilingual speakers (>11 years). These results are consistent with the hypothesis that language subprocesses are differentially sensitive to the timing of second-language experience.

Adolescent↗