Developmental changes in refractoriness of the cortical auditory evoked potential.

Objective: This study examined morphological changes in the cortical auditory evoked potential (CAEP) waveform as a function of varying stimulation rate. Stimuli were presented in a paradigm which indirectly assesses the refractory properties of the underlying neuronal generators.
Methods: CAEPs were recorded in 50 normal-hearing children (3-12 years) and 10 young adults (24-26 years). A speech sound was presented in a stimulus train with sequentially decreasing inter-stimulus intervals (ISIs) of 2000, 1000, 560, and 360ms. Latencies and amplitudes of the P1, N1, and P2 components at the Cz electrode were examined as a function of stimulus rate and age.
Results: Results revealed significant changes in the CAEP as a function of age and stimulation rate. At younger ages the N1-P2 component was elicited only at the slowest stimulation rates, and was more clearly apparent at successively faster stimulation rates as age increased.
Conclusions: We have described a stimulus paradigm that allows examination of the development of refractoriness by highlighting the interaction between age and rate on CAEP morphology.
Significance: Complex maturational patterns of CAEP components are best understood when the effects of both age and stimulus rate on the CAEP waveform are considered.