Lagged cells in the inferior colliculus of the awake ferret

Authors

  • Barak Shechter,

    1. Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, MD, USA
    2. Department of Biology, University of Maryland, College Park, MD 20742, USA
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  • Peter Marvit,

    1. Program in Neuroscience and Cognitive Science, Department of Psychology, University of Maryland, College Park, MD, USA
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  • Didier A. Depireux

    1. Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, MD, USA
    2. Institute for Systems Research, University of Maryland, College Park, MD, USA
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Dr B. Shechter, 2Department of Biology, as above.
E-mail: shechter@umd.edu

Abstract

Neurons in the primary auditory cortex (AI) encode complex features of the spectral content of sound, such as direction selectivity. Recent findings of temporal symmetry in AI predict a specific organization of the subcortical input into the cortex that contributes to the emergence of direction selectivity. We demonstrate two subpopulations of neurons in the central nucleus of the inferior colliculus, which differ in their steady-state temporal response profile: lagged and non-lagged. The lagged cells (23%) are shifted in temporal phase with respect to non-lagged cells, and are characterized by an ‘inhibition first’ and delayed excitation in their spectro-temporal receptive fields. Non-lagged cells (77%) have a canonical ‘excitation first’ response. However, we find no difference in the response onset latency to pure tone stimuli between the two subpopulations. Given the homogeneity of tonal response latency, we predict that these lagged cells receive inhibitory input mediated by cortical feedback projections.

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