Greenberg, D;
Monaghan, JJM;
Dietz, M;
Marquardt, T;
McAlpine, D;
(2017)
The influence of envelope waveform on ITD sensitivity of neurons in the auditory midbrain.
Journal of Neurophysiology
, 118
(4)
pp. 2358-2370.
10.1152/jn.01048.2015.
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Abstract
Interaural time differences (ITDs) conveyed by the modulated envelopes of high-frequency sounds can serve as a cue for localising a sound source. Klein-Hennig et al. (2011) demonstrated the envelope attack, the rate at which stimulus energy in the envelope increases, and the duration of the pause, the interval between successive envelope pulses, as important factors affecting sensitivity to envelope ITDs in human listeners. Modulated sounds with rapid attacks and long pauses produce the lowest ITD-discrimination thresholds. The duration of the envelope's sustained component (sustain) and the rate at which stimulus energy falls at the offset of the envelope (decay) are only minor factors. We assessed the responses of 71 single-neurons, recorded from the midbrains of 15 urethane anaesthetized tri-colored guinea pigs, to envelope shapes in which the four envelope components: attack, sustain, decay and pause, were systematically varied. We confirmed the importance of the attack and pause components in generating ITD-sensitive responses. Analysis of neural firing rates demonstrated more neurons (49/71) show ITD-sensitivity in response to damped stimuli (fast attack and slow decay) compared to ramped stimuli (slow attack and fast decay) (14/71). Further, the lowest threshold for the damped stimulus (91 μs) was a factor of 4 lower than for the temporally reversed ramped envelope shape (407 μs). The data confirm the importance fast attacks and optimal pause durations in generating sensitivity to ITDs conveyed in the modulated envelopes of high-frequency sounds and are incompatible with models of ITD processing based on the integration of sound energy over time.
| Type: | Article |
|---|---|
| Title: | The influence of envelope waveform on ITD sensitivity of neurons in the auditory midbrain |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1152/jn.01048.2015 |
| Publisher version: | http://dx.doi.org/10.1152/jn.01048.2015 |
| Language: | English |
| Additional information: | © 2017 the American Physiological Society Licensed under Creative Commons Attribution CC-BY 4.0: © the American Physiological Society. |
| Keywords: | Amplitude modulated, Envelope ITD, ITD sensitive neurons |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > The Ear Institute |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1564972 |
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