Electrophysiological evidence for attenuated auditory recovery cycles in children with specific language impairment

Previous research indicates that at least some children with specific language impairment (SLI) show a reduced neural response when non-linguistic tones were presented at rapid rates. However, this past research has examined older children, and it is unclear whether such deficits emerge earlier in development. It is also unclear whether atypical refractory effects differ for linguistic versus non-linguistic stimuli or can be explained by deficits in selective auditory attention reported among children with SLI. In the present study, auditory refractory periods were compared in a group of 24 young children with SLI (age 3-8 years) and 24 matched control children. Event-related brain potentials (ERPs) were recorded and compared to 100 ms linguistic and non-linguistic probe stimuli presented at inter-stimulus intervals (ISIs) of 200, 500, or 1000 ms. These probes were superimposed on story narratives when attended and ignored, permitting an experimental manipulation of selective attention within the same paradigm. Across participants, clear refractory effects were observed with this paradigm, evidenced as a reduced amplitude response from 100 to 200 ms at shorter ISIs. Children with SLI showed reduced amplitude ERPs relative to the typically-developing group at only the shortest, 200 ms, ISI and this difference was over the left-hemisphere for linguistic probes and over the right-hemisphere for non-linguistic probes. None of these effects was influenced by the direction of selective attention. Taken together, these findings suggest that deficits in the neural representation of rapidly presented auditory stimuli may be one risk factor for atypical language development.