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Faculty
Duck O. Kim
Professor of Neuroscience and Otolaryngology
kim@neuron.uchc.edu
Areas of Interest:
Neuroscience of the auditory system; computational neuroscience of
single neurons and neural systems; otolaryngology research using
otoacoustic emissions; biomedical engineering.
Our research seeks to integrate systems-neuroscience experimental
investigations with mathematical modeling. Neurophysiological methods
include single-unit recording of neurons in the auditory system of awake
animals. Modeling methods include digital computer simulations at each
of the following levels: ion channels, synapses distributed over the
dendrites and soma, single neurons and multi-neuron neural systems.
Lab Rotation Projects (in collaboration with Dr. S. Kuwada):
Neural coding of auditory distance
Localizing sounds is important to humans and animals for basic
functions such as escape from a threat, capturing a prey, and
communication. Neural mechanisms for localizing sounds in
two-dimensions, horizontal (azimuth) and vertical (elevation) angles,
have been studied extensively. In contrast, mechanisms responsible for
localization of distance, the third spatial dimension, are poorly
understood. A stimulus of any modality (auditory, visual or tactile)
presented at a close distance is particularly potent in evoking a
defensive response. This suggests that the brains of humans and animals
can recognize distance of a sensory stimulus (including sound)
particularly when the stimulus is nearby.
The present study is designed to break a new ground by investigating how
the brain processes auditory distance. Physiologically, we will measure
how neurons in the rabbit midbrain encode auditory distance. The
hypothesis is that neurons of the inferior colliculus (IC) convey
information about auditory distance based on a ratio of direct to
reverberant signal amplitudes (D/R ratio). We have recorded binaural
room impulse responses (BRIRs) of the rabbit in a reverberant acoustic
chamber. Analysis of the BRIR acoustic signals indicate that D/R ratio
systematically changes as a function of auditory distance. In this
research, virtual sound fields (with a sound source at a variable
location) will be created by combining BRIRs with a source signal and
presented to the rabbit. Responses of single neurons in the midbrain of
unanesthetized rabbits will be recorded in response to virtual sound
fields. Our preliminary observations indicate that the IC neurons
exhibit sensitivity to auditory distance.
The knowledge to be gained from this study should be useful in future
efforts to maximize the rehabilitative potential of hearing-impaired
patients so that optimal performance can be achieved in tasks involving
the binaural localization system such as recognizing speech in a noisy
cocktail-party setting.
Duck O. Kim
Laboratory Page
Selected Publications:
Kim DO, Moiseff A, Turner JB, Gull J, Acoustic cues underlying
auditory distance in barn owls, Acta Otolaryngol., 2008, in press.
Choi Y-S, Lee S-Y, Parham K, Neely ST, Kim DO, Stimulus-frequency
otoacoustic emission: Measurements in humans and simulations with an
active cochlear model, J. Acoust. Soc. Am, 2008, in press.
Kim DO, Yang XM, Ye Y (2003). A subpopulation of dorsal raphe nucleus
neurons retrogradely labeled with cholera toxin-B injected into the
inner ear. Exp Brain Res. 153: 514-521.
Kim DO, Yang XM, Neely DO (2003). Effects of the medial olivocochlear
reflex on cochlear mechanics: Experimental and modeling studies of DPOAE.
In Biophysics of the Cochlea: From Molecules to Models, A.W. Gummer,
World Scientific, New Jersey, pp 506-516.
Warr WB, Beck-Boche JE, Ye Y, Kim DO (2002). Organization of
olivocochlear neurons in the cat studied with the retrograde tracer
cholera toxin-B. J. Assoc. Res. Otolar. 3: 457-478.
Parham K, Sun XM, Kim DO. (2001). Noninvasive assessment of auditory
function in mice: auditory brainstem response and distortion product
otoacoustic emission. In Handbook of Mouse Auditory Research, JF Willott,
Ed., CRC Press, pp 37-58.
Kim DO, Dorn PA, Neely ST, Gorga MP. (2001). Adaptation of distortion
product otoacoustic emission in humans. J. Assoc. Res. Otolar. 2: 31-40.
Kim DO, D'Angelo WR. (2000). Computational model for the bushy cell of
the cochlear nucleus. Neurocomputing, 32-33, 189-196.
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