Auditory neuropathy--neural and synaptic mechanisms

Nat Rev Neurol. 2016 Mar;12(3):135-49. doi: 10.1038/nrneurol.2016.10. Epub 2016 Feb 19.


Sensorineural hearing impairment is the most common form of hearing loss, and encompasses pathologies of the cochlea and the auditory nerve. Hearing impairment caused by abnormal neural encoding of sound stimuli despite preservation of sensory transduction and amplification by outer hair cells is known as 'auditory neuropathy'. This term was originally coined for a specific type of hearing impairment affecting speech comprehension beyond changes in audibility: patients with this condition report that they "can hear but cannot understand". This type of hearing impairment can be caused by damage to the sensory inner hair cells (IHCs), IHC ribbon synapses or spiral ganglion neurons. Human genetic and physiological studies, as well as research on animal models, have recently shown that disrupted IHC ribbon synapse function--resulting from genetic alterations that affect presynaptic glutamate loading of synaptic vesicles, Ca(2+) influx, or synaptic vesicle exocytosis--leads to hearing impairment termed 'auditory synaptopathy'. Moreover, animal studies have demonstrated that sound overexposure causes excitotoxic loss of IHC ribbon synapses. This mechanism probably contributes to hearing disorders caused by noise exposure or age-related hearing loss. This Review provides an update on recently elucidated sensory, synaptic and neural mechanisms of hearing impairment, their corresponding clinical findings, and discusses current rehabilitation strategies as well as future therapies.

Publication types

  • Review

MeSH terms

  • Animals
  • Auditory Pathways / metabolism
  • Auditory Pathways / pathology*
  • Cochlear Nerve / metabolism
  • Cochlear Nerve / pathology
  • Hair Cells, Auditory, Inner / metabolism
  • Hair Cells, Auditory, Inner / pathology
  • Hearing Loss / diagnosis
  • Hearing Loss / metabolism
  • Hearing Loss / therapy
  • Hearing Loss, Central / diagnosis*
  • Hearing Loss, Central / metabolism
  • Hearing Loss, Central / therapy
  • Humans
  • Synapses / metabolism
  • Synapses / pathology*

Supplementary concepts

  • Auditory neuropathy