Loud noise damages the cochlear organ of Corti, particularly the outer hair cells, but this organ is not innervated by nociceptors of somatosensory ganglia, which detect damage elsewhere in the body. We have found a functional neuronal connection between cochlea and cochlear nucleus (CN) that respond not to sound, but to tissue damage caused by loud and persistent noise. This novel connection serves what we have termed auditory nociception. This novel sensory modality functions in Vglut3 KO mice, in which the canonical auditory pathway is completely silent as inner hair cells do not release glutamate and type I afferents are not stimulated. Instead, evidence indicates that this pathway is mediated by type II afferents and is not activated by neurotransmitter release, but by noise-induced tissue damage (such as the spilled contents of killed outer hair cells). By cFos immunoreactivity, we found neurons of cochlear nucleus activated by the novel auditory nociceptive pathway, and many of them are in the granule cell region, which is innervated by type II but not type I afferents. Our next goals are to identify the neurons of CN that participate in auditory nociception as well as to identify the other areas of brain that are activated by this pathway. To do so, we have the brain samples of the mice used for the above-described study, and hence do not need to use additional animals.
|Effective start/end date||6/1/14 → 5/31/15|
- Office of Naval Research (N00014-14-1-0709)