Zusammenfassung
Age-dependent hearing loss has been well documented in gerbils exceeding 2 years of age using physiological methods (e.g. [Mills et al. (1990) Hear, Res. 46, 201-210]). We determined behavioral thresholds for broad-band noise and pure-tone pulses in gerbils as a function of age. Contrary to expectations based on previously published physiological data. we found no significant (broad-band noise ...
Zusammenfassung
Age-dependent hearing loss has been well documented in gerbils exceeding 2 years of age using physiological methods (e.g. [Mills et al. (1990) Hear, Res. 46, 201-210]). We determined behavioral thresholds for broad-band noise and pure-tone pulses in gerbils as a function of age. Contrary to expectations based on previously published physiological data. we found no significant (broad-band noise and 10 kHz) or only a very small hearing loss (7 dB at 2 kHz) in 30-36-month-old animals. In animals over 3 years of age we observed. an increased spread of thresholds and threshold shifts exceeding 20 dB in some individuals. Behavioral thresholds of old gerbils from two breeding colonies (University of Regensburg and Medical University of South Carolina) were similar. Data from individual animals where thresholds were determined physiologically and behaviorally indicate that results from auditory brainstem response measurements show no shift at 18 months while subsequent measurements at 28 29 months revealed age-dependent threshold shifts of 10-15 dB. In contrast, thresholds determined by behavioral methods in these same individuals at 3133 months of age remained stable. (C) 2002 Elsevier Science B.V. All rights reserved.