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Developmental Auditory Physiology Laboratory

  • ​​Overview

    Research in this laboratory, under the direction of Dr. Edward J. Walsh and in collaboration with Dr. JoAnn ​​McGee, is directed toward understanding the normal development of vertebrate auditory systems, as well as the pathological basis of congenital and environmentally-induced deafness. Single neuron data acquired from both in vivo and in vitro brainstem preparations, as well as far- and near-field auditory evoked potentials and otoa​coustic emissions, are used in conjunction with neuropharmacological procedures to investigate the development of sensory cell and neural coding within the auditory system.

    Current research topics include:

    • A study of the role of thyroid hormone as a necessary transcriptional factor in the development of sensory and neural processing (both afferent and efferent) in the auditory system.
    • An experimental investigation of the functional role(s) of efferent (olivocochlear) projections onto sensory cells within the cochlea and neurotransmitter systems associated with those projections.
    • Studies designed to consider the physiological consequences of naturally occurring mutations or targeted mutagenesis of a variety of genes that produce proteins that are necessary for normal auditory development or that produce progressive deafness.
    • Studies designed to examine the developmental effects of chemically- or environmentally-induced toxicity on mechanical transduction within the cochlea and brainstem function (e.g., goitrogenic agents [propylthiouracil; methimazole], polychlorinated biphenyls [PCBs], organophosphates, and nicotine).
  • Facilities

    The laboratory is equipped to conduct neurophysiological ​(single neuron and ensemble evoked response), neuropharmacological and otoacoustic experiments. It includes a large, standard double-walled sound-attenuating room, two smaller booths, and microelectrode fabrication and histological facilities. Major electronic equipment includes devices for sound delivery, electrophysiological and acoustical recordings, microionophoresis and pressure-phoresis, and calibration. Pentium computers interfaced to 16-bit D/A and A/D converters and event timers control digital stimulus generation and real-time data acquisition and display utilizing custom-written software.

  • Publications

    Sanes, D.H., McGee, J. & Walsh, E.J. (1998). Metabotropic glutamate receptor activation modulates sound level processing in the cochlear nucleus. J. Neurophysiol. 80, 209-217.

    Walsh, E.J., McGee, J., McFadden, S.L. & Liberman, M.C. (1998). Long-term effects of sectioning the olivocochlear bundle in neonatal cats. J. Neurosci. 18, 3859-3869.

    Cai, Y., McGee, J. & Walsh, E.J. (2000). Contributions of ion conductances to the onset responses of octopus cells in the ventral cochlear nucleus: Simulation results. J. Neurophysiol. 83, 301-314.

    Snyder, R.L., Sinex, D.G., McGee, J. & Walsh, E.J. (2000). Acute spiral ganglion lesions change the tuning properties and tonotopic organization of cat inferior colliculus neurons. Hear. Res. 147, 200-220.

    McGee, J. & Walsh, E.J. (2001). Mouse models for Usher and Alport Syndromes. In J. Willott (Ed.), Handbook of Mouse Auditory Research: From Behavior to Molecular Biology. CRC Press, Boca Raton, pp. 557-579.

    ​Walsh, E.J. & McGee, J. (2001). Hypothyroidism in the Tshr mutant mouse. In J. Willott (Ed.), Handbook of Mouse Auditory Research: From Behavior to Molecular Biology. CRC Press, Boca Raton, pp. 537-555.