Journal of Neurophysiology, Vol 74, Issue 4 1689-1700, Copyright © 1995 by APS

ARTICLES

Responses of neurons in the auditory pathway of the barn owl to partially correlated binaural signals

Y. Albeck and M. Konishi
Division of Biology 216-76, California Institute of Technology, Pasadena 91125, USA.

1. Extracellular single-unit recording in anesthetized barn owls was used to study neuronal response to dichotic stimuli of variable binaural correlation (BC). Recordings were made in the output fibers of nucleus laminaris (NL), the anterior division of the ventral lateral lemniscal nucleus (VLVa), the core of the central nucleus of the inferior colliculus (ICcC), the lateral shell of the central nucleus of the inferior colliculus (ICcLS), and the external nucleus of the inferior colliculus (ICx). 2. The response of all neurons sensitive to interaural time difference (ITD) varied with BC. The relationship between BC and impulse number fits a linear, a parabolic, or a ramp model. A linear or parabolic model fits most neurons in low-level nuclei. Higher order neurons in ICx did not respond to noise bursts with strong negative binaural correlation, creating a ramp-like response to BC. 3. A neuron's ability to detect ITD varied as a function of BC. Conversely, a neuron's response to BC changed with ITD. Neurons in NL, VLVa, and ICcC show almost periodic ITD response curves. In these neurons peaks and troughs of ITD response curves diminished as BC decreased, creating a flat ITD response when BC = 0. When BC was set to -1, the most favorable ITD became the least favorable one and vice versa. The ITD response curve of ICx neurons usually has a single dominant peak. The response of those neurons to a negatively correlated noise pair (BC = -1) showed two ITD peaks, flanking the position of the primary peak. 4. The parabolic BC response of NL neurons fits the prediction of the cross-correlation model, assuming half-wave rectification of the sound by the cochlea. Linear response is not predicted by the model. However, the parabolic and the linear neurons probably do not belong to two distinct groups as the difference between them is not statistically significant. Thus, the cross-correlation model provides a good description of the binaural response not only in NL but also in VLVa and ICcC. 5. Almost all ramp neurons occurred in either ICx or ICcLS where neurons are more broadly tuned to frequency than those in the lower nuclei. The synthesis of this response type requires, however, not only the convergence of different frequency channels but also inhibition between different ITD channels. We modeled the ramp response as a three-step process. First, different spectral channels converge to create broad frequency tuning. The response to variation in BC will be linear (or parabolic) because it is a sum of linear (parabolic) responses. Second, the activity in some adjacent ITD channels is subtracted by lateral inhibition. Finally, the result is rectified using a high threshold to avoid negative activity.

This article has been cited by other articles:

				P. X. Joris, D. H. Louage, and M. van der Heijden Temporal Damping in Response to Broadband Noise. II. Auditory Nerve J Neurophysiol, April 1, 2008; 99(4): 1942 - 1952. [Abstract] [Full Text] [PDF]

				A. Reches and Y. Gutfreund Stimulus-Specific Adaptations in the Gaze Control System of the Barn Owl J. Neurosci., February 6, 2008; 28(6): 1523 - 1533. [Abstract] [Full Text] [PDF]

				M. Mc Laughlin, B. Van de Sande, M. van der Heijden, and P. X. Joris Comparison of Bandwidths in the Inferior Colliculus and the Auditory Nerve. I. Measurement Using a Spectrally Manipulated Stimulus J Neurophysiol, November 1, 2007; 98(5): 2566 - 2579. [Abstract] [Full Text] [PDF]

				A. Vogel and B. Ronacher Neural Correlations Increase Between Consecutive Processing Levels in the Auditory System of Locusts J Neurophysiol, May 1, 2007; 97(5): 3376 - 3385. [Abstract] [Full Text] [PDF]

				Y. Gutfreund and E. I. Knudsen Adaptation in the Auditory Space Map of the Barn Owl J Neurophysiol, August 1, 2006; 96(2): 813 - 825. [Abstract] [Full Text] [PDF]

				D. H. G. Louage, P. X. Joris, and M. van der Heijden Decorrelation Sensitivity of Auditory Nerve and Anteroventral Cochlear Nucleus Fibers to Broadband and Narrowband Noise J. Neurosci., January 4, 2006; 26(1): 96 - 108. [Abstract] [Full Text] [PDF]

				C. H. Keller and T. T. Takahashi Localization and Identification of Concurrent Sounds in the Owl's Auditory Space Map J. Neurosci., November 9, 2005; 25(45): 10446 - 10461. [Abstract] [Full Text] [PDF]

				J. L. Pena and M. Konishi Robustness of Multiplicative Processes in Auditory Spatial Tuning J. Neurosci., October 6, 2004; 24(40): 8907 - 8910. [Abstract] [Full Text] [PDF]

				M. W. Spitzer, A. D. S. Bala, and T. T. Takahashi A Neuronal Correlate of the Precedence Effect Is Associated With Spatial Selectivity in the Barn Owl's Auditory Midbrain J Neurophysiol, October 1, 2004; 92(4): 2051 - 2070. [Abstract] [Full Text] [PDF]

				K. E. Hancock and B. Delgutte A Physiologically Based Model of Interaural Time Difference Discrimination J. Neurosci., August 11, 2004; 24(32): 7110 - 7117. [Abstract] [Full Text] [PDF]

				J. L. Pena and M. Konishi From Postsynaptic Potentials to Spikes in the Genesis of Auditory Spatial Receptive Fields J. Neurosci., July 1, 2002; 22(13): 5652 - 5658. [Abstract] [Full Text] [PDF]

				J. L. Pena and M. Konishi Cellular mechanisms for resolving phase ambiguity in the owl's inferior colliculus PNAS, October 24, 2000; 97(22): 11787 - 11792. [Abstract] [Full Text] [PDF]

				D. C. Fitzpatrick, S. Kuwada, and R. Batra Neural Sensitivity to Interaural Time Differences: Beyond the Jeffress Model J. Neurosci., February 15, 2000; 20(4): 1605 - 1615. [Abstract] [Full Text] [PDF]

				C. H. Keller and T. T. Takahashi Binaural Cross-Correlation Predicts the Responses of Neurons in the Owl''s Auditory Space Map under Conditions Simulating Summing Localization J. Neurosci., July 1, 1996; 16(13): 4300 - 4309. [Abstract] [Full Text] [PDF]