Development of BSER in kittens: Evidence for different central and peripheral maturation rates

Abstract

Brainstem evoked responses (BSER) were recorded in 30 kittens from 7 litters. Animals were unanesthetized but restrained. Signals were condensation clicks presented in free field. Latencies and amplitudes of BSER waves I and V were measured at various times during the first 90 postnatal days. Plots of BSER component latencies as a function of postnatal age were computer‐fitted by decaying exponentials of the form Y = a + b* exp(−cX). In all kittens, wave I latency attained adult status earlier than wave V. At 90‐dB peak SPL, for example, 95% of the adult latency value was achieved at a mean age of 34.4 days for wave I and 38.1 days for wave V. The age‐versus‐latency plots are not simple offsets of each other, however. Wave I latency shows only a rapid decline to its asymptotic value, but wave V latency shows a rapid decline phase followed by an extended period of slow decline. The data support the notion that maturation of central auditory responses is not explained entirely by maturation of the cochlea and auditory nerve.