Plasticity of somatosensory inputs to the cochlear nucleus – Implications for tinnitus

This chapter reviews evidence for functional connections of the somatosensory and auditory systems at the very lowest levels of the nervous system. Neural inputs from the dosal root and trigeminal ganglia, as well as their brain stem nuclei, cuneate, gracillis and trigeminal, terminate in the cochlear nuclei. Terminations are primarily in the shell regions surrounding the cochlear nuclei but some terminals are found in the magnocellular regions of cochlear nucleus. The effects of stimulating these inputs on multisensory integration are shown as short and long-term, both suppressive and enhancing. Evidence that these projections are glutamatergic and are altered after cochlear damage is provided in the light of probable influences on the modulation and generation of tinnitus.

► The cochlear nucleus receives non-auditory as well as auditory inputs.
► Many of these inputs arise in the somatosensory system.
► Somatosensory inputs to the cochlear nucleus are glutamatergic.
► Somatosensory inputs to the cochlear nucleus are enhanced after cochlear damage.
►  Enhanced somatosensory input may lead to hyperactivity that represents tinnitus.