Genotypic Differences in Behavioral, Physiological and Anatomical Expressions of Age-Related Hearing Loss in the Laboratory Mouse: Original Papers Travaux originaux

Ameliorative Effects of Exposing DBA/2J Mice to an Augmented Acoustic Environment on Histological Changes in the Cochlea and Anteroventral Cochlear Nucleus

“…The number of IHCs and OHCs was computed as a function of distance from the apex in order to obtain a cochleogram: the mean number of hair cells within 0.12 mm lengths of the organ of Corti at 0.6-mm intervals from apex to base (OHC counts are the sum of the three rows). Counts are presented graphically in the figures mapped to correspond with cochleotopic frequency representation along the basilar membrane, synthesized from the cochleotopic maps of Ehret (1983) and Henry and Chole (1980).…”

“…In B6 mice high-frequency hearing loss is first observed at about two to three months of age (young adulthood), progresses gradually, and becomes profound during the second year of life (Ding et al 2001;Erway et al 1993;Henry and Chole 1980;Li and Borg 1991;Mikaelian 1979;. D2 mice exhibit very early hearing loss that is evident even at three weeks of age (Ralls 1967;Willott 1981;Willott et al 1982), about a week after the onset of hearing and prior to complete maturation of the central auditory system (Willott 1981;Willott et al 1984).…”

“…Degeneration of outer hair cells (OHCs), inner hair cells (IHCs), and other cochlear tissue underlie progressive hearing loss in B6 and D2 strains (Ding et al 2001;Henry and Chole 1980;Hequembourg and Liberman 2001;Ohlemiller and Gagnon 2004;Spongr et al 1997;Willott et al 1995). Willott and Bross (2004) assessed cochlear correlates of long-term, nightly AAE treatment on B6 mice at 12Y14 months of age (an age at which high-frequency hearing loss is severe).…”

Low-Frequency Tone Pips Elicit Exaggerated Startle Reflexes in C57BL/6J Mice with Hearing Loss

“…Its effects variously include fused and disorganized stereocilia, degenerating outer and inner hair cells and supporting cells including the spiral ligament, an atrophic stria vascularis, and loss in myelination and numbers of spiral ganglion cells (Mikaelian et al 1974;Henry and Chole 1980;Shnerson et al 1981;Willott et al 1987;Li and Hultcrantz 1994;Hequembourg and Liberman 2001). These structural changes are more evident at the base compared with the cochlear apex.…”

“…These structural changes are more evident at the base compared with the cochlear apex. The resulting age-related decrement in auditory sensitivity has been demonstrated in increased absolute thresholds for auditory-evoked potentials and behavioral-psychophysical tasks (Mikaelian et al 1974;Henry and Chole 1980;Shnerson and Pujol 1981;Willott 1986;Li and Borg 1991;Erway et al 1993; Kazee et al 1995;Spongr et al 1997;Hequembourg and Liberman 2001). Although the specific details of the pattern of sensory loss across frequency vary across studies, the most common outcome is that the early loss is most serious for high tonal frequencies but then spreads across the spectrum of hearing with increasing age.…”