Deviant neurophysiological asymmetry in children with language impairment.

Deviant anatomical asymmetry of perisylvian cortex is argued to be linked to specific language impairment (SLI). However, no studies have examined whether deviant functional asymmetry underlies the processing of spoken language. In the current study, brain-electrical activity was recorded from 31 scalp sites to the function word 'the' embedded in auditorally presented stories and nonsense contexts. The SLI children showed reversed asymmetry at electrode sites over temporal cortex compared to control children in processing this word in all contexts. They also appear to lack some contribution from a deep neural generator in processing 'the' in the story. This investigation is the first to demonstrate a direct link between deviant neurophysiological asymmetry and the processing of spoken language in children with SLI.

Maturation of mismatch negativity in school-age children.

OBJECTIVE: Event-related potentials were recorded to investigate the maturation of auditory processing in school-age children. DESIGN: The mismatch negativity (MMN) was obtained in an oddball tone discrimination paradigm in 66 school-age children and 12 adults. In the children's data, a prominent negativity to both the standard and deviant tone, peaking around 200 msec, was observed, and compared with the N1 auditory evoked potential component. RESULTS: The MMN was found to decrease with latency by 11 msec/yr from 4 to 10 yr of age. No developmental change in MMN amplitude was seen from 4 to 10 yr of age. However, the MMN amplitude was significantly smaller in adults than in children. The prominent negativity in children was significantly later than the adult N1 component, and did not change in latency from 4 to 10 yr of age. This finding adds to a body of evidence suggesting that this prominent negativity and the adult N1 are not the same component. The magnitude of the prominent negativity in children decreased slightly with age. CONCLUSION: Changes in the timing of the brain discriminative response, MMN, suggest systematic maturational changes in auditory processing.