Hidden hearing loss and endbulbs of Held: Evidence for central pathology before detection of ABR threshold increases

Michael A. Muniak, Femi E. Ayeni, David Kay Ryugo

Research output: Contribution to journalArticle

Abstract

Reductions in sound-evoked activity in the auditory nerve due to hearing loss have been shown to cause pathological changes in central auditory structures. Hearing loss due strictly to the aging process are less well documented. In this study of CBA/CaH mice, we provide evidence for age-related pathology in the endbulb of Held, a large axosomatic ending arising from myelinated auditory nerve fibers. Endbulbs are known to be involved in the processing of temporal cues used for sound localization and speech comprehension. Hearing thresholds as measured by auditory brainstem response (ABR) thresholds remained stable up to one year, whereas suprathreshold amplitudes of early ABR waves decreased by up to 50% in older mice, similar to that reported for age-related cochlear synaptopathy (Sergeyenko et al., 2013). The reduction of ABR response magnitude with age correlated closely in time with the gradual atrophy of endbulbs of Held, and is consistent with the hypothesis that endbulb integrity is dependent upon normal levels of spike activity in the auditory nerve. These results indicate that central auditory pathologies emerge as consequence of so-called “hidden” hearing loss and suggest that such brain changes require consideration when devising therapeutic interventions.

Original languageEnglish (US)
JournalHearing Research
DOIs
StateAccepted/In press - Jan 1 2018
Externally publishedYes

Fingerprint

Cochlear Nerve
Brain Stem Auditory Evoked Potentials
Hearing Loss
Pathology
Sound Localization
Myelinated Nerve Fibers
Inbred CBA Mouse
Cochlea
Hearing
Atrophy
Cues
Brain
Therapeutics

Keywords

  • Auditory brainstem response
  • Auditory nerve
  • Cochlear nucleus
  • Neurobiotin

ASJC Scopus subject areas

  • Sensory Systems

Cite this

Hidden hearing loss and endbulbs of Held : Evidence for central pathology before detection of ABR threshold increases. / Muniak, Michael A.; Ayeni, Femi E.; Ryugo, David Kay.

In: Hearing Research, 01.01.2018.

Research output: Contribution to journalArticle

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