Maturation and effect of stimulus rate on brainstem auditory evoked potentials.

Brainstem auditory evoked potentials (BAEPs) at three stimulus rates (20, 41.3 and 61.3 c/s) were recorded in 104 normal preterm infants, distributed in four age groups between 32 and 39 weeks (conceptional age), and in 20 normal adults. The latency shifts between 61.3 c/s and 20 c/s, and between 41.3 c/s and 20 c/s, were calculated for each wave, and studied as a function of age. A significant effect of conceptional age was shown on the '61.3-20 c/s' and the '41.3-20 c/s' wave V latency shifts, and a significant difference between adults and newborns was noted for the wave V and wave III latency shifts. No significant difference was obtained for the wave I latency shifts. This suggests that the changes of auditory adaptation with maturation may be predominantly at a central level, i.e. on central synapses.