Planar multipolar cells in the cochlear nucleus project to medial olivocochlear neurons in mouse

Authors

  • Keith N. Darrow,

    Corresponding author
    1. Department of Communication Sciences and Disorders, Worcester State University, Worcester, Massachusetts 01564
    2. Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
    • Worcester State University, Department of Communication Sciences and Disorders, Worcester, MA, 01564
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  • Thane E. Benson,

    1. Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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  • M. Christian Brown

    1. Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
    2. Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts 02114
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Abstract

Medial olivocochlear (MOC) neurons originate in the superior olivary complex and project to the cochlea, where they act to reduce the effects of noise masking and protect the cochlea from damage. MOC neurons respond to sound via a reflex pathway; however, in this pathway the cochlear nucleus cell type that provides input to MOC neurons is not known. We investigated whether multipolar cells of the ventral cochlear nucleus have projections to MOC neurons by labeling them with injections into the dorsal cochlear nucleus. The projections of one type of labeled multipolar cell, planar neurons, were traced into the ventral nucleus of the trapezoid body, where they were observed terminating on MOC neurons (labeled in some cases by a second cochlear injection of FluoroGold). These terminations formed what appear to be excitatory synapses, i.e., containing small, round vesicles and prominent postsynaptic densities. These data suggest that cochlear nucleus planar multipolar neurons drive the MOC neuron's response to sound. J. Comp. Neurol. 520:1365–1375, 2012. © 2011 Wiley Periodicals, Inc.

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