Electrophysiological and morphological development of the inner ear in Belgian Waterslager canaries

• Published in: Hearing research 2010-10, Vol.269 (1), p.56-69
• Main Authors: Brittan-Powell, Elizabeth F., Dooling, Robert J., Ryals, Brenda, Gleich, Otto
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation; Aging - pathology; Aging - physiology; Animals; Auditory Threshold - physiology; Biological and medical sciences; Canaries - growth & development; Canaries - physiology; Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Ear, Inner - growth & development; Ear, Inner - physiopathology; Electrophysiological Phenomena - physiology; Evoked Potentials, Auditory, Brain Stem - physiology; Fundamental and applied biological sciences. Psychology; Hair Cells, Auditory, Inner - pathology; Hair Cells, Auditory, Inner - physiology; Hair Cells, Auditory, Inner - ultrastructure; Hearing Loss - physiopathology; Medical sciences; Microscopy, Electron, Scanning; Models, Animal; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Non tumoral diseases; Otorhinolaryngology. Stomatology; Reaction Time - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/j.heares.2010.07.003

Belgian Waterslager (BW) canaries have an inherited hearing loss due to missing and abnormal hair cells, but it is unclear whether the loss is congenital or developmental. We used auditory brainstem responses and scanning electron microscopy to describe the development of auditory sensitivity and hair cell abnormalities in BW and non-BW canaries. In both strains, adult ABR thresholds were higher than behavioral thresholds, but BW canaries exhibited higher thresholds than non-BW canaries across all frequencies. Immediately post-hatch, ABR thresholds and hair cell numbers were similar in both strains. Two weeks later, thresholds were significantly higher in BW canaries, and hair cell number progressively decreased as the birds aged. These data show that in BW canaries: the peripheral auditory system is functionally similar to non-BW canary from hatch to 2 weeks, ABR thresholds improve during this developmental period, actually becoming better than those of adults, but then worsen as the bird continues to age. Hair cell number and appearance is similar to non-BW canaries at hatch but progressively declines after 30 days of age. These data show that the hearing loss characteristic of BW canaries is, at least in part, developmental and is established by the time song learning begins. ► Adult BW canaries exhibited higher ABR thresholds than non-BW canaries. ► Post-hatch, ABR thresholds & hair cell numbers were similar in both strains. ► ABR thresholds in BW canaries improve but then worsen as the bird continues to age. ► Hair cell number and appearance progressively declines after 30 days of age. ► Hearing loss in BW canaries is progressive & established when song learning begins.