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Response properties of neurons in the core of the central nucleus of the inferior colliculus of the barn owl
Author(s) -
Wagner Hermann,
Mazer James A.,
Von Campenhausen Mark
Publication year - 2002
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2002.01970.x
Subject(s) - barn owl , inferior colliculus , monaural , interaural time difference , neuroscience , sound localization , octave (electronics) , physics , nucleus , acoustics , biology , paleontology , predation
The central nucleus of the inferior colliculus (ICC) is particularly important for the processing of interaural time differences (ITDs). In the barn owl, neuronal best frequencies in a subnucleus of the ICC, the ICCcore, span the animal's entire hearing range (≈ 200–10 000 Hz). This means that low‐frequency ITD‐sensitive ICCcore neurons in the owl can be directly compared to ITD‐sensitive mammalian ICC neurons with similar best frequencies as well as to the high‐frequency ITD‐sensitive neurons usually studied in owls. This report represents a first attempt to systematically describe important physiological properties of ICCcore neurons in the barn owl, with particular attention to the low‐frequency region (< 2 kHz). Responses were obtained from 133 neurons or small clusters of neurons; recording sites were confirmed by histological reconstruction of electrode tracks based on electrolytic lesions. Iso‐intensity frequency response functions were typically ≈ 1 octave wide in the low‐frequency range and ≈ 1/3 octave wide in the high‐frequency range. Most neurons were ITD‐tuned; both noise and pure tone stimuli yielded periodic ITD tuning curves with several equivalent response maxima. In most cases ITD tuning curves had a response peak within the barn owl's physiological ITD range. ITD tuning widths were inversely correlated with neuronal best frequency. None of the ICCcore neurons studied were sensitive to interaural level differences. Monaural inputs to ICCcore cells were typically binaurally balanced, i.e. they exhibited similar response thresholds, dynamic ranges, slopes and saturation levels, for both left and right ear monaural stimulation.