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Grothe, Benedikt ORCID: 0000-0001-7317-0615; Covey, Ellen; Casseday, John H. (1996): Spatial tuning of neurons in the inferior colliculus of the big brown bat: Effects of sound level, stimulus type and multiple sound sources. In: Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, Vol. 179, No. 1: pp. 89-102
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Abstract

We examined factors that affect spatial receptive fields of single units in the central nucleus of the inferior colliculus of Eptesicus fuscus. Pure tones, frequency- or amplitude-modulated sounds, or noise bursts were presented in the free-held, and responses were recorded extracellularly. For 58 neurons that were tested over a 30 dB range of sound levels, 7 (12%) exhibited a change of less than 10 degrees in the center point and medial border of their receptive field. For 28 neurons that were tested with more than one stimulus type, 5 (18 %) exhibited a change of less than 10 degrees in the center point and medial border of their receptive field. The azimuthal response ranges of 19 neurons were measured in the presence of a continuous broadband noise presented from a second loudspeaker set at different fixed azimuthal positions. For 3 neurons driven by a contralateral stimulus only, the effect of the noise was simple masking. For 11 neurons driven by sound at either side, 8 were unaffected by the noise and 1 showed a simple masking effect. For the remaining 2, as well as for 5 neurons that were excited by contralateral sound and inhibited by ipsilateral sound, the peak of the azimuthal response range shifted toward the direction of the noise.