Human sound localization at near-threshold levels

Sabin, Andrew T.; Macpherson, Ewan A.; Middlebrooks, John C.

doi:10.1016/j.heares.2004.08.001

Cited by 63 publications

(66 citation statements)

References 31 publications

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“…Psychophysical data were collected from 7 normal human subjects using 16 spatial locations and 4 absolute stimulus intensities. These data were consistent with previous reports of the effects of intensity on sound localization performance in both humans (23)(24)(25)(26) and monkeys (27). The localization results are summarized across subjects in Fig.…”

Section: Resultssupporting

confidence: 92%

“…This is in contrast to models using spike rate as well as spike timing and pattern, wherein ipsilateral locations are discriminated as well as contralateral locations (e.g., 14,[16][17]. Second, sound localization ability is degraded at low stimulus intensities (23)(24)(25)(26)(27). The results from this study also demonstrate an influence of stimulus intensity on sound localization ability that was consistent across all studied subjects.…”

Section: Discussioncontrasting

confidence: 62%

“…Correlates between the population responses in 6 different cortical areas were compared to psychophysical studies from normal human subjects localizing the same acoustic stimuli. Specifically, we tested whether the cortical population code could accurately predict the stimulus location consistent with 2 basic aspects related to the sound localization performance of normal and lesioned primates: (i) contralateral space is better represented than ipsilateral space, giving rise to contralesional deficits (1-4); and (ii) higher-intensity stimuli are better localized than lowerintensity stimuli (23)(24)(25)(26)(27).…”

mentioning

confidence: 99%

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Populations of auditory cortical neurons can accurately encode acoustic space across stimulus intensity

Miller¹,

Recanzone

2009

Proc. Natl. Acad. Sci. U.S.A.

115

103

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The auditory cortex is critical for perceiving a sound's location. However, there is no topographic representation of acoustic space, and individual auditory cortical neurons are often broadly tuned to stimulus location. It thus remains unclear how acoustic space is represented in the mammalian cerebral cortex and how it could contribute to sound localization. This report tests whether the firing rates of populations of neurons in different auditory cortical fields in the macaque monkey carry sufficient information to account for horizontal sound localization ability. We applied an optimal neural decoding technique, based on maximum likelihood estimation, to populations of neurons from 6 different cortical fields encompassing core and belt areas. We found that the firing rate of neurons in the caudolateral area contain enough information to account for sound localization ability, but neurons in other tested core and belt cortical areas do not. These results provide a detailed and plausible population model of how acoustic space could be represented in the primate cerebral cortex and support a dual stream processing model of auditory cortical processing.auditory cortex ͉ macaque ͉ population model ͉ sound localization S ound localization is a fundamental function of the auditory system in terrestrial vertebrates. Unilateral lesions of the auditory cortex have been shown to produce deficits in contralesional space in a variety of species (1-4), indicating a critical role for auditory cortex. However, despite considerable effort to determine how the cerebral cortex processes acoustic space, our understanding remains rudimentary (e.g., 5-17). From these studies and others, we know that (i) acoustic space is not topographically organized in the mammalian cerebral cortex and (ii) single neuron spatial receptive fields are very broad and, in themselves, unlikely to account for localization ability. Thus, some form of population code is likely used to represent acoustic space in the auditory cortex. Several models have been proposed (e.g., 13, 17), yet they do not illustrate how such a coding scheme could actually work, and it remains unclear which aspects of the neuronal response carry the information. Recent studies in extrastriate visual cortex have shown that a logarithmic maximum-likelihood estimator could account for direction selectivity of visual motion based on the firing rate of populations of neurons (18). The perception of azimuthal acoustic space can be similarly modeled as direction over 360°, and such an estimator may be a common cortical process for encoding secondary stimulus properties.A recent study examining single neuron recordings in the macaque auditory cortex (22) was consistent with the hypothesis put forth by Rauschecker and others (19-21) that acoustic space could be represented in a hierarchical fashion, starting in the core field(s) of auditory cortex and progressing to the belt and para-belt fields. That study showed that spatial tuning of single neurons was sharpest in the caudolateral (CL...

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Section: Resultssupporting

confidence: 92%

Section: Discussioncontrasting

confidence: 62%

mentioning

confidence: 99%

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Populations of auditory cortical neurons can accurately encode acoustic space across stimulus intensity

Miller¹,

Recanzone

2009

Proc. Natl. Acad. Sci. U.S.A.

115

103

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“…This is likely due to the ability to recruit more neurons to provide information about stimulus location as more neurons are activated by the greater spectral energy of the stimulus. The second basic stimulus parameter is the intensity of the stimulus, with low-intensity stimuli being most difficult to localize and louder stimuli more easily localized (e.g., Altshuler & Comalli 1975, Comalli & Altshuler 1976, Recanzone & Beckerman 2004, Sabin et al 2005, Su & Recanzone 2001. Again, as the louder sounds will engage a greater population of neurons, it is possible that the size of the neuronal pool is important in processing acoustic space information.…”

Section: Sound Localization Psychophysicsmentioning

confidence: 99%

“…These cues also require that the stimulus be loud enough to permit detection of all of the decreases in energy, or notches. Thus, pure tone stimuli are extremely difficult to localize in elevation (e.g., Recanzone et al 2000b), as are very-low-intensity stimuli (e.g., Recanzone & Beckerman 2004, Sabin et al 2005, Su & Recanzone 2001. Because the spectral bandwidth of neurons in the primary auditory cortex can be quite narrow (Recanzone et al 2000a), a population-coding scheme is necessary to encode acoustic space at the cortical level.…”

Section: Monaural Cuesmentioning

confidence: 99%

The biological basis of audition

Recanzone

2010

WIRES Cognitive Science

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Interest has recently surged in the neural mechanisms of audition, particularly with regard to functional imaging studies in human subjects. This review emphasizes recent work on two aspects of auditory processing. The first explores auditory spatial processing and the role of the auditory cortex in both nonhuman primates and human subjects. The interactions with visual stimuli, the ventriloquism effect, and the ventriloquism aftereffect are also reviewed. The second aspect is temporal processing. Studies investigating temporal integration, forward masking, and gap detection are reviewed, as well as examples from the birdsong system and echolocating bats.

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Cortical Representation of Auditory Space

King

Middlebrooks

2010

The Auditory Cortex

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Human sound localization at near-threshold levels

Cited by 63 publications

References 31 publications

Populations of auditory cortical neurons can accurately encode acoustic space across stimulus intensity

Populations of auditory cortical neurons can accurately encode acoustic space across stimulus intensity

The biological basis of audition

Cortical Representation of Auditory Space

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