Auditory ERP components and mismatch negativity in dysphasic children.

Auditory event-related potentials (ERPs) and especially the mismatch negativity component (MMN) were examined in 14 dysphasic and 12 normal children (aged 7-13). The ERPs were elicited by sine tone stimuli using the passive oddball paradigm and short ISI (350 msec). We measured the peak latency and peak amplitude of MMN responses to frequency (500/553 Hz) and duration (50/110 msec or 50/500 msec) differences. In the dysphasic group the peak amplitude of the frequency MMN was significantly attenuated. The duration MMN showed a significant difference between the two groups only for stimuli with highly contrasting values (50/500 msec). In normal subjects we found a negative correlation between the peak latency of the frequency MMN and age. The maturational changes of long-latency ERPs were non-significant in dysphasic children. Evidence of differences in hemispheric asymmetry between the two groups was observed.