title: The postnatal development of frequency-place code and tuning characteristics in the auditory midbrain of the phyllostomid bat, Carollia perspicillata.
abstract: This report describes the postnatal development of hearing range, auditory sensitivity and tonotopy within the inferior colliculus (IC) of a mammal specialized for ultrasonic hearing. The experimental animal, Carollia perspicillata, has an adult hearing range of 7-110 kHz (characteristic frequencies) but lack any significant overrepresentation of a limited frequency band as known for rhinolophoid bats and Pteronotus. The audiogram of the newborn Carollia includes characteristic frequencies from 8 to 76 kHz, which is about 65% of the adult hearing range. As in adults, low frequencies are represented in the dorsolateral portion of the IC. However, at birth the ventromedial IC is non-responsive to acoustic stimulation up to intensities of 90 dB SPL. During development there is a progressive conversion of non-responsive IC areas into acoustically responsive slabs with characteristic frequencies above 76 kHz along the dorsolateral to ventromedial (low-to-high frequency) IC axis. This development is superimposed by a non-uniform shift of characteristic frequency: a decrease of CFs in dorsolateral regions, and an increase of CFs in ventromedial areas. The results suggest a bidirectional shift of frequency representation along the cochlear tonotopic axis.
authors.affiliation: Lehrstuhl für Allgemeine Zoologie und Neurobiologie, Ruhr-Universität Bochum, FRG.
authors.forename: S J
authors.initials: SJ
authors.lastname: Sterbing
authors.forename: U
authors.initials: U
authors.lastname: Schmidt
authors.forename: R
authors.initials: R
authors.lastname: Rübsamen
mesh_terms: D000161:Acoustic Stimulation; D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development* / Q000502:physiology; D001299:Audiometry / Q000662:veterinary; D001303:Auditory Cortex / Q000254:growth & development* / Q000502:physiology; D001309:Auditory Threshold / Q000502:physiology*; D001921:Brain / Q000254:growth & development / Q000502:physiology; D002685:Chiroptera / Q000254:growth & development* / Q000502:physiology; D004594:Electrophysiology; D007245:Inferior Colliculi / Q000254:growth & development* / Q000502:physiology; D014465:Ultrasonics; D014828:Vocalization, Animal