Recovery of the cortical evoked potential from auditory stimulation in children and adults

The recovery of cortical evoked potentials to auditory stimulation was studied in a group of 12 young adults and 12 children aged 9.0-13.3 years. Subjects listened to single clicks and to pairs of clicks in which the interstimulus intervals (ISI's) varied, taking on values of 50, 100, 250, 500, 750, and 1000 msec. Average evoked potentials (AEP's) based on 50 repetitions were obtained to single clicks by coherent averaging and to the 2nd click of the pairs by automatically subtracting the evoked potential to each single click from the evoked potential to the corresponding pair and coherently averaging the remainder. In children, peak latencies of the P1, N1, and P2 components of the AEP to the 2nd click of the pairs increased significantly with decreasing ISI; in adults, latencies similarly increased except in the case of the N1 component. These increases were significantly larger in children than in adults, indicating that cortical recovery is slower in children and suggesting that cortical excitability in children may be lower. Peak latencies of the P1, N1, and P2 components of the AEP to single clicks were significantly lower (16-21 msec) in the children.