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Neurobiology of the Auditory System

   One area of research in the Kim Auditory Neuroscience Laboratory  is a combined physiological and anatomical study of the cochlear nucleus and other auditory structures in the brain stem. In the physiological experiments, action potentials of single neurons are recorded with microelectrodes in the cat or mouse using a computerized system for controlling stimulus delivery and for acquiring response data. We are studying the marginal shell of the ventral cochlear nucleus (VCN) which is a unique subdivision that receives afferent inputs exclusively from low spontaneous-rate auditory nerve fibers. This research will evaluate the hypothesis that the VCN marginal shell is optimally suited for encoding stimulus intensity (Neurosci. Lett. 205, 71-74, 1996; J. Neurophysiol., 77, 2083-2097, 1997) and that it projects to olivocochlear neurons. We will also investigate the dorsal cochlear nucleus (DCN) in the normal cats and mice and in mutant mice (e.g., pcd) where a specific class of neurons (e.g., cartwheel cells) are missing in the DCN resulting from a genetic disorder.

From Kim et al., 1995, Active Hearing, A. Flock et al., Eds., Academic Press.
Copyright (C) 1995 Elsevier Science Ltd.

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From Ghoshal & Kim (1997, J. Neurophysiol. 77, p 2086).
Copyright (C) 1997 The American Physiological Society
If you want to get a whole-page view of the above figures, click inside a figure.

     The anatomical study will conduct microscopic tract tracing by using a survival procedure of the cat and transport of anterograde and retrograde tracers: biotinylated dextran amine, horseradish peroxidase and tritiated leucine (using autoradiography). Brain tissue is processed for histological examination. Labeled nerve fibers and cell bodies are traced using a computerized microscope system consisting of Neurolucida System running on a Windows 95 computer combined with a Leitz Diaplan microscope. With this system, we are able to trace small structures, some less than a micrometer in diameter, visualizing under a high magnification while, at the same time, keeping track of the absolute coordinates of the structures within a large area of an entire tissue section by means of a computer-controlled high-precision stepping motor controlling the microscope stage.

        Kim, D.O. (1980). Cochlear mechanics: implications of electrophysiological and acoustical obaservations.  Hearing Res. 2, 297-317.
        Kim, D.O.(1984). “Functional roles of the inner- and outrer-hair-cell subsystems in the cochlea and brainstem” In Hearing Science, C.I. Berlin, Ed., College-Hill Press, San Diego, CA, pp 241-261. Click to view the article .
        Kim, D.O. (1986). Active and nonlinear cochlear biomechanics and the role of outer-hair-cell subsystem in the mammalian auditory system. Hearing Res. 22, 105-114.
        Kim, D.O., Parham, K., Zhao, H. and Ghoshal, S. (1995). The olivocochlear feedback gain control subsystem: ascending input from the small cell cap of the cochlear nucleus? In "Active Hearing" edited by A. Flock, D. Ottoson, M. Ulfendahl (Elsevier Science Ltd., New York), pp 31-51.
        Parham, K and Kim, D.O. (1995). Spontaneous and sound-evoked discharge characteristics of complex-spiking neurons in the dorsal cochlear nucleus of unanesthetized decerebrate cat. J. Neurophysiol. 73, 550-561.
        Zhao, H., Parham, K., Ghoshal, S. and Kim, D.O. (1995). Small neurons in the vestibular nerve root project to the marginal shell of the anteroventral cochlear nucleus in the cat. Brain Res. 700, 295-298.
        Ghoshal, S. and Kim, D.O. (1996). Marginal shell of the anteroventral cochlear nucleus: Intensity coding in single units of the unanesthetized decerebrate cat. Neurosci. Lett. 205, 71-74.
        Ghoshal, S. and Kim, D.O. (1996). Marginal shell of the anteroventral cochlear nucleus: Acoustically weakly-driven and not-driven units in the unanesthetized decerebrate cat. Acta Otolaryngol. (Stockh.) 116, 280-283.
        Parham, K., Zhao, H.B. and Kim, D.O. (1996). Responses of auditory nerve fibers of the unanesthetized decerebrate cat to click pairs as simulated echoes. J. Neurophysiol. 76, 17-29.
        Kim, D.O. and Parham, K. (1997). Physiology of the auditory nerve. Invited chapter of Encyclopedia of Acousticcs, M.J. Crocker, Ed. (John Wiley & Sons, New York), vol. 3, p 1371-1379.
         Ghoshal, S. and Kim, D.O. (1997). Marginal shell of the anteroventral cochlear nucleus: Single-unit response properties in the unanesthetized decerebrate cat. J. Neurophysiol. 77, 2083-2097.
       Kim, D.O., Ghoshal, S. and Ye, Y. (1998). Integration of ascending and descending signals representing stimulus intensity in the marginal shell of the anteroventral cochlear nucleus. In Psychophysical and Physiological Advances in Hearing, A. R. Palmer et al., Eds., Whurr Pub., London, pp 195-203.
       Parham, K., Zhao, H.B., Ye, Y. and Kim, D.O. (1998).  Responses of anteroventral cochlear nucleus neurons of the unanesthetized decerebrate cat to click pairs as simulated echoes.  Hearing Res. 125, 131-146.
        Sun, X.M. and Kim, D.O. (1999). Adaptation of 2f1-f2 distortion product otoacoustic emission in young-adult and old CBA and C57 mice.  J. Acoust. Soc. Am. 105, 3399-3409.
        Fitzpatrick DC, Kuwad S, Kim DO, Parham K, Batra R. (1999). Responses of neurons to click-pairs as simulated echoes: auditory nerve to auditory cortex.  J. Acoust. Soc. Am. 106: 3460-3472.
    Ye Y, Machado DG, Kim DO. (2000). Projection of the marginal shell of the anteroventral cochlear nucleus to olivocochlear neurons in the cat.  J. Comp. Neurol. 420:  127-138. Click to view the article , or a color figure .
       Parham K, Bonaiuto G, Carlson S, Turner JG, D'Angelo WR, Bross LS, Fox A., Willott JF, Kim DO. 2000. Purkinje cell degeneration and control mice: responses of single units in the dorsal cochlear nucleus and the acoustic startle response. Hearing Res. 148: 137-152.
    Ye Y, Kim DO. (2001). Connections between the dorsal raphe nucleus and a hindbrain region consisting of the cochlear nucleus and neighboring structures. Acta Otolaryngol. 121: 284-288. Click to view the article .
    Kim DO, Dorn PA, Neely ST, Gorga MP. (2001). Adaptation of distortion product otoacoustic emission in humans. J. Assoc. Res. Otolar. 2: 31-40. Click to view the article .
       Parham K, Sun XM, Kim DO. 2000. 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, in press. Click to view the article .