Reversal of hemispheric asymmetry on auditory tasks in children who are poor listeners

We examined hemispheric activation patterns during auditory and visual processing in two groups of children: 13 boys in the age range from 9 to 12 years rated by their parents and teachers as poor listeners and 11 boys in the same age range rated as normal listeners. Three tasks were employed: auditory gap detection, detection of auditory movement, and a control task involving visuospatial discrimination. Electrical activity was recorded from 30 scalp electrodes as participants responded to target stimuli in an event-related potential paradigm. In the visual task, hemispheric activation was relatively symmetric around the midsagittal plane in both groups. In the two auditory tasks, however, hemispheric activation patterns differed significantly between groups. In the normal-listener group, activation was asymmetric to the right hemisphere. In the poor-listener group, however, activation tended toward asymmetry, favoring the left hemisphere. These results suggest that abnormalities in hemispheric lateralization of function may underlie the auditory processing problems of at least some children described as poor listeners.