Postnatal Developement of the Cochlea in Horseshoe Bats
The mammalian cochlea exhibits immature features in early postnatal development. Physiological responses are restricted to the low frequency range, and structural maturation is proceeding from basal cochlear locations towards the apex (review: Romand, 1983). The development of the cochlear frequency representation is an intriguing problem, however there are few frequency mapping studies in mammals. Cochlear microphonic measurements in gerbils showed that in postnatal development a shift in frequency place map takes place for basal regions of the cochlea (Arjmand et al., 1988) which are tuned to frequencies about 1.5 octaves lower than in the adult. The hypothesis that a reorganization of the cochlear frequency mapping pattern occurs during development (Lippe and Rubel, 1983) is thus supported for locations responsive to high frequencies in adult mammals, although it does not apply for apical cochlear regions (Arjmand et al., 1988) and has been generelly questioned by a developmental study in birds (Manley et al., 1987).
KeywordsOuter Hair Cell Cochlear Nucleus Postnatal Development Early Postnatal Development Tuning Characteristic
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