Frequency-dependent interaural delays in the medial superior olive: implications for interaural cochlear delays

Day, Mitchell L.; Semple, Malcolm N.

doi:10.1152/jn.00131.2011

Cited by 55 publications

(62 citation statements)

References 55 publications

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“…Possibly there is some ecological advantage to this dramatic change in sensitivity. In contrast with the gerbil, which appears to employ a range of neural mechanisms to extend the upper frequency range of ITD sensitivity (Day and Semple, 2011), human listeners may benefit from reduced sensitivity to ITD fine-structure at frequencies above 1400 Hz. This reduction would mitigate the increasing ambiguity for humans in encoding fine-structure ITD in narrow-band stimuli as sound frequencies increase-where, due to the relatively large human head-size, the ITDs become greater than half a period of the stimulus, and ITD images appear on the wrong side of the midline (Sayers, 1964).…”

Section: Ecological Advantagementioning

confidence: 99%

Human interaural time difference thresholds for sine tones: The high-frequency limit

Brughera

Dunai

Hartmann

2013

The Journal of the Acoustical Society of America

164

184

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The smallest detectable interaural time difference (ITD) for sine tones was measured for four human listeners to determine the dependence on tone frequency. At low frequencies, 250-700 Hz, threshold ITDs were approximately inversely proportional to tone frequency. At mid-frequencies, 700-1000 Hz, threshold ITDs were smallest. At high frequencies, above 1000 Hz, thresholds increased faster than exponentially with increasing frequency becoming unmeasurably high just above 1400 Hz. A model for ITD detection began with a biophysically based computational model for a medial superior olive (MSO) neuron that produced robust ITD responses up to 1000 Hz, and demonstrated a dramatic reduction in ITD-dependence from 1000 to 1500 Hz. Rate-ITD functions from the MSO model became inputs to binaural display models-both place based and rate-difference based. A place-based, centroid model with a rigid internal threshold reproduced almost all features of the human data. A signal-detection version of this model reproduced the high-frequency divergence but badly underestimated low-frequency thresholds. A rate-difference model incorporating fast contralateral inhibition reproduced the major features of the human threshold data except for the divergence. A combined, hybrid model could reproduce all the threshold data.

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Section: Ecological Advantagementioning

confidence: 99%

Human interaural time difference thresholds for sine tones: The high-frequency limit

Brughera

Dunai

Hartmann

2013

The Journal of the Acoustical Society of America

164

184

View full text Add to dashboard Cite

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“…Several mechanisms may underlie this way of detecting ITD. Apart from axonal delays, cochlear delays were proposed to underlie frequency-dependent ITD tuning ("stereausis"; Shamma et al, 1989;Joris et al, 2006;Day and Semple, 2011). Precisely timed glycinergic inhibition shaped ITD detection in small mammals (Brand et al, 2002;Pecka et al, 2008;Leibold, 2010), constituting a third possible mechanism.…”

Section: Itd Sensitivity In Different Frequency Bands Across the Popumentioning

confidence: 99%

Transformation from a Pure Time Delay to a Mixed Time and Phase Delay Representation in the Auditory Forebrain Pathway

Vonderschen¹,

Wagner²

2012

J. Neurosci.

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Birds and mammals exploit interaural time differences (ITDs) for sound localization. Subsequent to ITD detection by brainstem neurons, ITD processing continues in parallel midbrain and forebrain pathways. In the barn owl, both ITD detection and processing in the midbrain are specialized to extract ITDs independent of frequency, which amounts to a pure time delay representation. Recent results have elucidated different mechanisms of ITD detection in mammals, which lead to a representation of small ITDs in high-frequency channels and large ITDs in low-frequency channels, resembling a phase delay representation. However, the detection mechanism does not prevent a change in ITD representation at higher processing stages. Here we analyze ITD tuning across frequency channels with pure tone and noise stimuli in neurons of the barn owl's auditory arcopallium, a nucleus at the endpoint of the forebrain pathway. To extend the analysis of ITD representation across frequency bands to a large neural population, we employed Fourier analysis for the spectral decomposition of ITD curves recorded with noise stimuli. This method was validated using physiological as well as model data. We found that low frequencies convey sensitivity to large ITDs, whereas high frequencies convey sensitivity to small ITDs. Moreover, different linear phase frequency regimes in the high-frequency and low-frequency ranges suggested an independent convergence of inputs from these frequency channels. Our results are consistent with ITD being remodeled toward a phase delay representation along the forebrain pathway. This indicates that sensory representations may undergo substantial reorganization, presumably in relation to specific behavioral output.

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“…Bonham and Lewis (1999), on the other hand, showed that a simple coincidence detector with CF-mismatched AN inputs can produce a curvature in the phase plot for pure-tone stimuli. Day and Semple (2011) also showed that a model MSO cell with CF-mismatched AN inputs can reproduce the nonlinear phase plots observed in MSO neurons for low-frequency pure tones. The key factor in these two models is the frequencydependent cochlear delay mismatch induced by the mismatch in the CFs of the AN inputs from the two sides.…”

Section: Ic Responses To Sam Tonesmentioning

confidence: 81%

Dual sensitivity of inferior colliculus neurons to ITD in the envelopes of high-frequency sounds: experimental and modeling study

Wang

Devore

Delgutte

et al. 2014

Journal of Neurophysiology

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Wang L, Devore S, Delgutte B, Colburn HS. Dual sensitivity of inferior colliculus neurons to ITD in the envelopes of high-frequency sounds: experimental and modeling study. J Neurophysiol 111: 164 -181, 2014. First published October 23, 2013 doi:10.1152/jn.00450.2013.-Human listeners are sensitive to interaural time differences (ITDs) in the envelopes of sounds, which can serve as a cue for sound localization. Many high-frequency neurons in the mammalian inferior colliculus (IC) are sensitive to envelope-ITDs of sinusoidally amplitude-modulated (SAM) sounds. Typically, envelope-ITD-sensitive IC neurons exhibit either peak-type sensitivity, discharging maximally at the same delay across frequencies, or trough-type sensitivity, discharging minimally at the same delay across frequencies, consistent with responses observed at the primary site of binaural interaction in the medial and lateral superior olives (MSO and LSO), respectively. However, some high-frequency IC neurons exhibit dual types of envelope-ITD sensitivity in their responses to SAM tones, that is, they exhibit peak-type sensitivity at some modulation frequencies and trough-type sensitivity at other frequencies. Here we show that high-frequency IC neurons in the unanesthetized rabbit can also exhibit dual types of envelope-ITD sensitivity in their responses to SAM noise. Such complex responses to SAM stimuli could be achieved by convergent inputs from MSO and LSO onto single IC neurons. We test this hypothesis by implementing a physiologically explicit, computational model of the binaural pathway. Specifically, we examined envelope-ITD sensitivity of a simple model IC neuron that receives convergent inputs from MSO and LSO model neurons. We show that dual envelope-ITD sensitivity emerges in the IC when convergent MSO and LSO inputs are differentially tuned for modulation frequency. inferior colliculus; amplitude modulation; interaural time differences; computational modeling; sound localization PSYCHOPHYSICAL STUDIES have shown that human listeners can detect interaural time differences (ITDs) conveyed via the envelopes of high-frequency sounds Trahiotis 1994, 2002;Henning 1974;Klumpp and Eady 1956;McFadden and Pasanen 1976;Nuetzel and Hafter 1976). Physiologically, the superior olivary complex (SOC) is considered to be the primary site for encoding ITDs in the ascending auditory pathway. Both principal nuclei of the SOC, the medial superior olive (MSO) and the lateral superior olive (LSO), contain high-frequency neurons that are sensitive to the envelope-ITD of sinusoidally amplitude-modulated (SAM) tones, although they appear to encode ITD in different ways.MSO neurons receive predominantly excitatory inputs from both ears (Batra et al. 1997;Caird and Klinke 1983;Goldberg and Brown 1968;Langford 1984;Yin and Chan 1990), resulting in peak discharge rate when neural activities from both sides arrive coincidentally. These neurons are called "peak type" because their ITD tuning functions align at their peaks for sounds of different frequencies. In con...

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Frequency-dependent interaural delays in the medial superior olive: implications for interaural cochlear delays

Cited by 55 publications

References 55 publications

Human interaural time difference thresholds for sine tones: The high-frequency limit

Human interaural time difference thresholds for sine tones: The high-frequency limit

Transformation from a Pure Time Delay to a Mixed Time and Phase Delay Representation in the Auditory Forebrain Pathway

Dual sensitivity of inferior colliculus neurons to ITD in the envelopes of high-frequency sounds: experimental and modeling study

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