Postnatal development of physiological responses in auditory nerve fibers

Publisher Website
Google Scholar
Abstract
The discharges of auditory nerve fibers in kittens 4-37 days of age were recorded from micropipette electrodes. Tuning curves, thresholds and the degree of tuning (Q 10) are compared over this age range. The tuning curves for fibers during the 1st postnatal week are relatively flat, with thresholds > 100 dB SPL [sound pressure level]. The response areas of VIII-nerve fibers during this period are restriced to low-to-middle frequencies. With increasing age there is a reduction in threshold and an increase in the sharpness of tuning which is dependent on fiber CF [characteristic frequency]. Response characteristics similar to adult VIII-nerve fibers were observed first for fibers with CF near 5 RHz. For the response measures used here, VIII-nerve fibers in kittens are adult-like by the 3rd to 4th postnatal week. The results are discussed in relation to the morphological development of the cochlea reported by other investigators.