Sensitivity of single neurons in auditory cortex of cat to binaural tonal stimulation; effects of varying interaural time and intensity.

Brugge, John F.; Dubrovsky, N. A.; Aitkin, Lindsay; Anderson, D. J.

doi:10.1152/jn.1969.32.6.1005

Cited by 205 publications

(61 citation statements)

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“…In these experiments, the exact relationship between neural response and an interaural cue was often critically dependent on the intensity level of the source (Brugge et al 1969(Brugge et al , 1973Irvine et al 1996;Irvine 1981, 1983;Reale and Brugge 1990;Reale and Kettner 1986;Semple and Kitzes 1993a,b). Thus for most AI cells, uncertainty in the intensity level of the source introduces an inherent ambiguity between a given response and the interaural difference cue that maps onto the azimuthal direction of that source.…”

Section: Discussionmentioning

confidence: 99%

Directional Sensitivity of Neurons in the Primary Auditory (AI) Cortex: Effects of Sound-Source Intensity Level

Reale

Jenison

Brugge

2003

Journal of Neurophysiology

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Transient sounds were delivered from different directions in virtual acoustic space while recording from single neurons in primary auditory cortex (AI) of cats under general anesthesia. The intensity level of the sound source was varied parametrically to determine the operating characteristics of the spatial receptive field. The spatial receptive field was constructed from the onset latency of the response to a sound at each sampled direction. Spatial gradients of response latency composing a receptive field are due partially to a systematic co-dependence on sound-source direction and intensity level. Typically, at any given intensity level, the distribution of response latency within the receptive field was unimodal with a range of approximately 3–4 ms, although for some cells and some levels, the spread could be as much as 20 or as little as 2 ms. Response latency, averaged across directions, differed among neurons for the same intensity level, and also differed among intensity levels for the same neuron. Generally, increases in intensity level resulted in decreases in the mean and variance, which follows an inverse Gaussian distribution. Receptive field models, based on response latency, are developed using multiple parameters (azimuth, elevation, intensity), validated with Monte Carlo simulation, and their spatial filtering described using spherical harmonic analysis. Observations from an ensemble of modeled receptive fields are obtained by linking the inverse Gaussian density to the probabilistic inverse problem of estimating sound-source direction and intensity. Upper bounds on acuity is derived from the ensemble using Fisher information, and the predicted patterns of estimation errors are related to psychophysical performance.

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Section: Discussionmentioning

confidence: 99%

Directional Sensitivity of Neurons in the Primary Auditory (AI) Cortex: Effects of Sound-Source Intensity Level

Reale

Jenison

Brugge

2003

Journal of Neurophysiology

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“…One role of latency within the IC and its ascending targets is to gate the integration of inputs that carry information about related sounds, such as the inputs from different ears that signal the location of auditory stimuli (Brugge et al, 1969;Pollak, 1988;Park, 1998). In some echolocating bats, the wide range of latencies of IC neurons are also thought to serve as a potential source for calculating convergent maps of the delay between echolocation sweeps and returning echoes, a feature corresponding to target range (Kuwabara and Suga, 1993;Park and Pollak, 1993;Hattori and Suga, 1997).…”

Section: Functional Consequencesmentioning

confidence: 99%

Serotonin Shifts First-Spike Latencies of Inferior Colliculus Neurons

Hurley¹,

Pollak²

2005

J. Neurosci.

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Many studies of neuromodulators have focused on changes in the magnitudes of neural responses, but fewer studies have examined neuromodulator effects on response latency. Across sensory systems, response latency is important for encoding not only the temporal structure but also the identity of stimuli. In the auditory system, latency is a fundamental response property that varies with many features of sound, including intensity, frequency, and duration. To determine the extent of neuromodulatory regulation of latency within the inferior colliculus (IC), a midbrain auditory nexus, the effects of iontophoretically applied serotonin on first-spike latencies were characterized in the IC of the Mexican free-tailed bat. Serotonin significantly altered the first-spike latencies in response to tones in 24% of IC neurons, usually increasing, but sometimes decreasing, latency. Serotonin-evoked changes in latency and spike count were not always correlated but sometimes occurred independently within individual neurons. Furthermore, in some neurons, the size of serotonin-evoked latency shifts depended on the frequency or intensity of the stimulus, as reported previously for serotonin-evoked changes in spike count. These results support the general conclusion that changes in latency are an important part of the neuromodulatory repertoire of serotonin within the auditory system and show that serotonin can change latency either in conjunction with broad changes in other aspects of neuronal excitability or in highly specific ways.

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“…It is clear that auditory cortex is necessary for ITD processing in both animals and humans, though lesions in either hemisphere cause a contralateral deficit in spatial processing in animals (Jenkins and Masterton, 1982;Jenkins and Merzenich, 1984;Malhotra et al, 2004), while right auditory cortex appears both necessary and sufficient for ITD processing in humans (Yamada et al, 1996;Tanaka et al, 1999). ITD tuning in primary auditory cortex (A1) was first reported several decades ago (Brugge et al, 1969;Brugge and Merzenich, 1973), but the few studies in A1 with large samples that have been performed since have produced inconsistent results: a study in cats reported results similar to those in subcortical areas, with nearly all cells responding preferentially to ITDs corresponding to locations in the contralateral hemifield (Reale and Brugge, 1990), while studies in chinchillas, rabbits, and monkeys reported a weaker contralateral bias with preferred ITDs distributed more evenly across the physiological range (Benson and Teas, 1976;Fitzpatrick et al, 2000;Scott et al, 2009). There have been no direct studies of single-cell ITD sensitivity in human cortex, but recent EEG and MEG studies suggest a strong contralateral bias (Magezi and Krumbholz, 2010;Salminen et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

The Neural Representation of Interaural Time Differences in Gerbils Is Transformed from Midbrain to Cortex

2014

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Interaural time differences (ITDs) are the dominant cue for the localization of low-frequency sounds. While much is known about the processing of ITDs in the auditory brainstem and midbrain, there have been relatively few studies of ITD processing in auditory cortex. In this study, we compared the neural representation of ITDs in the inferior colliculus (IC) and primary auditory cortex (A1) of gerbils. Our IC results were largely consistent with previous studies, with most cells responding maximally to ITDs that correspond to the contralateral edge of the physiological range. In A1, however, we found that preferred ITDs were distributed evenly throughout the physiological range without any contralateral bias. This difference in the distribution of preferred ITDs in IC and A1 had a major impact on the coding of ITDs at the population level: while a labeled-line decoder that considered the tuning of individual cells performed well on both IC and A1 responses, a two-channel decoder based on the overall activity in each hemisphere performed poorly on A1 responses relative to either labeled-line decoding of A1 responses or two-channel decoding of IC responses. These results suggest that the neural representation of ITDs in gerbils is transformed from IC to A1 and have important implications for how spatial location may be combined with other acoustic features for the analysis of complex auditory scenes.

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Sensitivity of single neurons in auditory cortex of cat to binaural tonal stimulation; effects of varying interaural time and intensity.

Cited by 205 publications

References 0 publications

Directional Sensitivity of Neurons in the Primary Auditory (AI) Cortex: Effects of Sound-Source Intensity Level

Directional Sensitivity of Neurons in the Primary Auditory (AI) Cortex: Effects of Sound-Source Intensity Level

Serotonin Shifts First-Spike Latencies of Inferior Colliculus Neurons

The Neural Representation of Interaural Time Differences in Gerbils Is Transformed from Midbrain to Cortex

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