In normal hearing, the dorsal cochlear nucleus is the first stop in the brain for sound signals arriving from the ear via the auditory nerve. Its also a hub where multitasking neurons process sensory signals from other parts of the brain.
In this study, we showed that when there is a hearing loss, other parts of the brain that normally convey signals to the cochlear nucleus have an enhanced effect, says Shore, who is also an associate professor in the Department of Molecular and Integrative Physiology at the U-M Medical School.
When you take one source of excitation away, another source comes in to make up for it. The somatosensory system is coming in, but may overcompensate and help cause tinnitis, she says.
The somatosensory system is a nerve network in the body that provides information to the brain about touch, vibration, skin temperature and pain. The part of the system that provides sensations from the face and head, called the trigeminal system, brings signals to the cochlear nucleus that help us hear and speak.
But when people experience hearing loss or some other event, such as having a cavity filled or a tooth implanted, these neurons from the face and head can respond like overly helpful relatives in a family crisis. The resulting neuron firings in the cochlear nucleus, like too many phone calls, create the din of tinnitus, a phantom sound produced in the brain.
In the study, Shore and the papers second author Seth Koehler, a U-M Ph.D. student in the U-M departments of Otolaryngology an
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| Contact: Anne Rueter arueter@umich.edu 734-764-2220 University of Michigan Health System Source:Eurekalert |