University of California, Irvine, 19722077 Kansas Life Sciences Innovations Center
3901 Rainbow Boulevard
Kansas City, KS 66160-7401
Phone: (913) 588-7407
Fax: (913) 588-7430
timig@kumc.edu
Tinnitus is the perception of phantom noise that is often associated with sensorineural hearing loss. Tinnitus presumably reflects aberrant spontaneous activity (SA, neuronal discharge in the absence of sound stimulation) in the central auditory system, although relatively little is known about normal and aberrant patterns of SA. Current research in this lab has two objectives, 1) to characterize the effect of tinnitus-producing unilateral noise damage on SA in the rat’s auditory system, and 2) to assess the contribution of ascending projections from the dorsal cochlear nucleus and descending projections from the cerebral cortex to the control of SA in the inferior colliculus. 2) This is done using both the [14C]-2-deoxyglucose (2DG) method to provide information on synaptic activity, and electrophysiological recordings to provide information on neuronal discharge rate. A more detailed understanding of both normal and aberrant patterns of SA and mechanisms that control SA are important in understanding the pathophysiology of tinnitus and may give clues regarding new approaches to control tinnitus in patients. Further development of the rodent model may provide a valuable tool to test the effect of experimental tinnitus therapies.
Samson, F.K., P. Barone, J.C. Clarey and T.J. Imig. Effects of ear plugging on single unit azimuth sensitivity in cat primary auditory cortex: II. Azimuth tuning dependent upon binaural stimulation. J. Neurophysiol. 71:2194-2216, 1994.
Clarey, J.C., P. Barone and T.J. Imig. Functional organization of sound direction and sound pressure level in primary auditory cortex of the cat. J. Neurophysiol. 72:2383-2403, 1994.
Barone, P., J.C. Clarey, W.A. Irons, and T.J. Imig. Cortical synthesis of azimuth-sensitive single-unit responses with nonmonotonic level tuning: a thalamocortical comparison in the cat. J. Neurophysiol. 75:1206-1220, 1996.
Imig, T.J., P. Poirier, W.A. Irons, and F.K. Samson. Monaural spectral contrast mechanism for neural sensitivity to sound direction in the medial geniculate body of the cat. J. Neurophysiol. 78:2754-2771, 1997.
Imig, T.J., Bibikov, N.G., Poirier, P., and Samson, F.K. Directionality derived from pinna-cue spectral notches in the cat’s dorsal cochlear nucleus. J. Neurophysiol. 83:907-925, 2000.
Samson, F.K., Barone, P., Irons, W.A., Clarey, J.C., Poirier, P., and Imig, T.J. Directionality derived from differential sensitivity to monaural and binaural cues in the cat’s medial geniculate body. J. Neurophysiol. 84: 907-922, 2000.
Poirier, P., Samson, F.K. and Imig, T.J. Spectral shape sensitivity contributes to azimuth tuning of neurons in the cat’s inferior colliculus. J. Neurophysiol. 89: 2760-2777, 2003.
Bibikov, N.G., Imig, T.J. and Samson, F.K. Hazard functions and functions of expected spike density for neurons in the cat cochlear nucleus (in Russian). Russian Journal of Physiology, 89: 682-699, 2003.
Bibikov, N., Imig, T. and Samson, F. Hazard functions and expected spike density functions for neuron spike activity in the cochlear nucleus of the cat. Neuroscience and Behavioral Physiology 35: 59-70, 2005.
Imig, T.J. and Durham, D. Effect of unilateral noise exposure on the tonotopic distribution of spontaneous activity in the cochlear nucleus and inferior colliculus in the cortically intact and decorticate rat. J. Comp. Neurol. 490: 391-413, 2005.
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