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Representation of lnteraural Time Difference in the Central Nucleus of the Barn Owl's Inferior Colliculus

Wagner, Hermann and Takahashi, Terry and Konishi, Masakazu (1987) Representation of lnteraural Time Difference in the Central Nucleus of the Barn Owl's Inferior Colliculus. Journal of Neuroscience, 7 (10). pp. 3105-3116. ISSN 0270-6474. PMCID PMC6569176. doi:10.1523/jneurosci.07-10-03105.1987.

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This paper investigates the role of the central nucleus of the barn owl's inferior colliculus in determination of the sound-source azimuth. The central nucleus contains many neurons that are sensitive to interaural time difference (ITD), the cue for azimuth in the barn owl. The response of these neurons varies in a cyclic manner with the ITD of a tone or noise burst. Response maxima recur at integer multiples of the period of the stimulating tone, or, if the stimulus is noise, at integer multiples of the period corresponding to the neuron's best frequency. Such neurons can signal, by means of their relative spike rate, the phase difference between the sounds reaching the left and right ears. Since an interaural phase difference corresponds to more than one ITD, these neurons represent ITD ambiguously. We call this phenomenon phase ambiguity. The central nucleus is tonotopically organized and its neurons are narrowly tuned to frequency. Neurons in an array perpendicular to isofrequency laminae form a physiological and anatomical unit; only one ITD, the array-specific ITD, activates all neurons in an array at the same relative level. We, therefore, may say that, in the central nucleus, an ITD is conserved in an array of neurons. Array-specific ITDs are mapped and encompass the entire auditory space of the barn owl. Individual space-specific neurons of the external nucleus, which receive inputs from a wide range of frequency channels (Knudsen and Konishi, 1978), are selective for a unique ITD. Space-specific neurons do not show phase ambiguity when stimulated with noise (Takahashi and Konishi, 1986). Space-specific neurons receive inputs from arrays that are selective for the same ITD. The collective response of the neurons in an array may be the basis for the absence of phase ambiguity in space-specific neurons.

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Additional Information:© 1987 by Society for Neuroscience. For the first six months after publication SfN’s license will be exclusive. Beginning six months after publication the Work will be made freely available to the public on SfN’s website to copy, distribute, or display under a Creative Commons Attribution 4.0 International (CC BY 4.0) license ( Received Aug. 5, 1986; revised Apr. 3, 1987; accepted Apr. 14, 1987. We thank C. E. Carr, W. E. Sullivan, and S. F. Volman for their help throughout the work, and, in addition to them, E. I. Knudsen, C. Köppl, and G. Manley for their comments on an earlier draft of the manuscript. E. Akutagawa helped us with histology. J. Knierim and D. Bilitch instructed us on the use of the computer microscope. This work was supported by NIH Grant 14617, NSF Grant 57033, and the Max-Planck-Gesellschaft.
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Issue or Number:10
PubMed Central ID:PMC6569176
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Official Citation:Representation of interaural time difference in the central nucleus of the barn owl's inferior colliculus H Wagner, T Takahashi, and M Konishi The Journal of Neuroscience, 1 October 1987, 7(10):3105-3116
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62529
Deposited By: Ruth Sustaita
Deposited On:02 Dec 2015 16:36
Last Modified:10 Nov 2021 23:03

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