The medial nucleus of the trapezoid body in rat: spectral and temporal properties vary with anatomical location of the units

Authors

  • Sandra Tolnai,

    1. Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca, Spain
    2. Auditory Neurophysiology Unit, Laboratory for the Neurobiology of Hearing, Institute for Neuroscience of Castilla y Leon, University of Salamanca, Salamanca, Spain
    3. Institute of Biology II, University of Leipzig, Leipzig, Germany
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  • Olga Hernandez,

    1. Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca, Spain
    2. Auditory Neurophysiology Unit, Laboratory for the Neurobiology of Hearing, Institute for Neuroscience of Castilla y Leon, University of Salamanca, Salamanca, Spain
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  • Bernhard Englitz,

    1. Institute of Biology II, University of Leipzig, Leipzig, Germany
    2. Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
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  • Rudolf Rübsamen,

    1. Institute of Biology II, University of Leipzig, Leipzig, Germany
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  • Manuel S. Malmierca

    1. Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca, Spain
    2. Auditory Neurophysiology Unit, Laboratory for the Neurobiology of Hearing, Institute for Neuroscience of Castilla y Leon, University of Salamanca, Salamanca, Spain
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Dr M.S. Malmierca, 1Department of Cell Biology and Pathology, as above.
E-mail: msm@usal.es

Abstract

The medial nucleus of the trapezoid body (MNTB) is a distinct nucleus in the superior olivary complex that transforms excitatory input from the cochlear nucleus into a widespread inhibitory output to distinct auditory brainstem nuclei. Few studies have dealt with the response properties of MNTB neurons to sound stimulation using in vivo preparations. In order to have a better understanding of the functional significance of the MNTB in auditory processing we report the basic temporal and spectral response properties of its principal cells using single-unit extracellular recordings to acoustic stimulation with pure tones and amplitude-modulated stimuli in the rat. Ninety-seven per cent of units showed V-shaped frequency response areas. Rate level functions were mainly saturating (51%) or monotonic (45%) at high intensities. Post-stimulus time histograms typically were characterised as primary-like with notch (59%) or primary-like (33%). Units showed good phase-locking to sinusoidally amplitude-modulated signals with vector strength VS values up to 0.87. Modulation transfer functions had low-pass shapes at near-threshold levels, with cut-off frequencies ranging from 370 to 1270 Hz. Exploration of the relationship between the temporal and spectral properties and the location of the units in the MNTB yielded characteristic frequency (CF)-dependent response properties (latency, Q10 and cut-off frequency) following a medio-lateral gradient, and CF-independent response features (maximum firing rate) following a dorso-ventral gradient.

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