An anatomically based frequency-place map for the mouse cochlea.
An anatomically based frequency-place map was created for the mouse using C57BL/CBA F1 hybrids by matching noise-induced lesions in the organ of Corti with permanent hearing losses as determined by auditory brainstem response (ABR) thresholds. Twenty-six mice developed 'notched' ABR threshold shifts after exposure to an octave band of noise with a center frequency of 2 kHz at 120 dB SPL for 24 h, 4 kHz at 110 dB SPL for 4 h or 8 kHz at 100 dB SPL for 1 or 2 h. ABR thresholds were determined at several intervals post-exposure until thresholds stabilized (14-27 days). Once thresholds had stabilized, the mice were killed and their cochleas were prepared for phase-contrast microscopic examination as plastic-embedded flat preparations. Hair cell loss, stereocilia damage, and myelinated nerve fiber degeneration as a function of percentage distance from the cochlear apex were determined. Frequency-position matches could be made for 22 of the 26 mice by correlating areas of hair cell loss/stereocilia damage with permanent changes in ABR thresholds. These frequency-position data were fitted with the equation: % Distance from apex=56.6 log (f(Hz))-179.1; r(2)=0.810. This frequency-place function agrees well with Ehret's (1975) theoretical function based on critical bands and masked auditory thresholds.
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Washington University School of Medicine, Department of Otolaryngology, 660 South Euclid Avenue, Box 8115, St. Louis, MO 63110, USA.
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Bohne
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D000818:Animals; D002923:Cilia / Q000473:pathology; D003051:Cochlea / Q000294:innervation / Q000473:pathology / Q000502:physiology*; D004056:Differential Threshold; D016057:Evoked Potentials, Auditory, Brain Stem; D006198:Hair Cells, Auditory / Q000473:pathology; D006317:Hearing Loss, Noise-Induced / Q000473:pathology / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008858:Microscopy, Phase-Contrast; D008954:Models, Biological; D009410:Nerve Degeneration / Q000473:pathology; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009622:Noise; D009925:Organ of Corti / Q000473:pathology