scholarly journals Simple transformations capture auditory input to cortex

2020 ◽  
Vol 117 (45) ◽  
pp. 28442-28451
Author(s):  
Monzilur Rahman ◽  
Ben D. B. Willmore ◽  
Andrew J. King ◽  
Nicol S. Harper
Keyword(s):  
Auditory Nerve ◽  
Time Course ◽  
Primary Auditory Cortex ◽  
Auditory Pathway ◽  
Auditory Nerve Fiber ◽  
Neural Responses ◽  
Auditory Periphery ◽  
Cortical Responses ◽  
Combined Models ◽  
Simple Models

Sounds are processed by the ear and central auditory pathway. These processing steps are biologically complex, and many aspects of the transformation from sound waveforms to cortical response remain unclear. To understand this transformation, we combined models of the auditory periphery with various encoding models to predict auditory cortical responses to natural sounds. The cochlear models ranged from detailed biophysical simulations of the cochlea and auditory nerve to simple spectrogram-like approximations of the information processing in these structures. For three different stimulus sets, we tested the capacity of these models to predict the time course of single-unit neural responses recorded in ferret primary auditory cortex. We found that simple models based on a log-spaced spectrogram with approximately logarithmic compression perform similarly to the best-performing biophysically detailed models of the auditory periphery, and more consistently well over diverse natural and synthetic sounds. Furthermore, we demonstrated that including approximations of the three categories of auditory nerve fiber in these simple models can substantially improve prediction, particularly when combined with a network encoding model. Our findings imply that the properties of the auditory periphery and central pathway may together result in a simpler than expected functional transformation from ear to cortex. Thus, much of the detailed biological complexity seen in the auditory periphery does not appear to be important for understanding the cortical representation of sound.

scholarly journals Simple spectral transformations capture the contribution of peripheral processing to cortical responses to natural sounds

2019 ◽  
Author(s):  
Monzilur Rahman ◽  
Ben D. B. Willmore ◽  
Andrew J. King ◽  
Nicol S. Harper
Keyword(s):  
Auditory Nerve ◽  
Time Course ◽  
Sensory Information ◽  
Primary Auditory Cortex ◽  
Neural Responses ◽  
Natural Sounds ◽  
Auditory Periphery ◽  
Cortical Responses ◽  
Spectral Transformations ◽  
Simple Models

AbstractProcessing in the sensory periphery involves various mechanisms that enable the detection and discrimination of sensory information. Despite their biological complexity, could these processing steps sub-serve a relatively simple transformation of sensory inputs, which are then transmitted to the CNS? Here we explored both biologically-detailed and very simple models of the auditory periphery to find the appropriate input to a phenomenological model of auditory cortical responses to natural sounds. We examined a range of cochlear models, from those involving detailed biophysical characteristics of the cochlea and auditory nerve to very pared-down spectrogram-like approximations of the information processing in these structures. We tested the capacity of these models to predict the time-course of single-unit neural responses recorded in the ferret primary auditory cortex, when combined with a linear non-linear encoding model. We show that a simple model based on a log-spaced, log-scaled power spectrogram with Hill-function compression performs as well as biophysically-detailed models of the cochlea and the auditory nerve. These findings emphasize the value of using appropriate simple models of the periphery when building encoding models of sensory processing in the brain, and imply that the complex properties of the auditory periphery may together result in a simpler than expected functional transformation of the inputs.

scholarly journals Fine frequency tuning in monkey auditory cortex and thalamus

2011 ◽  
Vol 106 (2) ◽  
pp. 849-859 ◽  
Author(s):  
Edward L. Bartlett ◽  
Srivatsun Sadagopan ◽  
Xiaoqin Wang
Keyword(s):  
Auditory Cortex ◽  
Auditory Nerve ◽  
Animal Studies ◽  
De Novo ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Auditory Pathway ◽  
Nerve Fibers ◽  
Frequency Resolution ◽  
Human Auditory Cortex

The frequency resolution of neurons throughout the ascending auditory pathway is important for understanding how sounds are processed. In many animal studies, the frequency tuning widths are about 1/5th octave wide in auditory nerve fibers and much wider in auditory cortex neurons. Psychophysical studies show that humans are capable of discriminating far finer frequency differences. A recent study suggested that this is perhaps attributable to fine frequency tuning of neurons in human auditory cortex (Bitterman Y, Mukamel R, Malach R, Fried I, Nelken I. Nature 451: 197–201, 2008). We investigated whether such fine frequency tuning was restricted to human auditory cortex by examining the frequency tuning width in the awake common marmoset monkey. We show that 27% of neurons in the primary auditory cortex exhibit frequency tuning that is finer than the typical frequency tuning of the auditory nerve and substantially finer than previously reported cortical data obtained from anesthetized animals. Fine frequency tuning is also present in 76% of neurons of the auditory thalamus in awake marmosets. Frequency tuning was narrower during the sustained response compared to the onset response in auditory cortex neurons but not in thalamic neurons, suggesting that thalamocortical or intracortical dynamics shape time-dependent frequency tuning in cortex. These findings challenge the notion that the fine frequency tuning of auditory cortex is unique to human auditory cortex and that it is a de novo cortical property, suggesting that the broader tuning observed in previous animal studies may arise from the use of anesthesia during physiological recordings or from species differences.

scholarly journals Binaural processing by the gecko auditory periphery

2011 ◽  
Vol 105 (5) ◽  
pp. 1992-2004 ◽  
Author(s):  
Jakob Christensen-Dalsgaard ◽  
Yezhong Tang ◽  
Catherine E. Carr
Keyword(s):  
Auditory Nerve ◽  
Auditory Pathway ◽  
Peak Frequency ◽  
Auditory Periphery ◽  
Transmission Delays ◽  
Binaural Processing ◽  
Mouth Cavity ◽  
Tokay Gecko ◽  
Interaural Level Differences ◽  
Nerve Recordings

Lizards have highly directional ears, owing to strong acoustical coupling of the eardrums and almost perfect sound transmission from the contralateral ear. To investigate the neural processing of this remarkable tympanic directionality, we combined biophysical measurements of eardrum motion in the Tokay gecko with neurophysiological recordings from the auditory nerve. Laser vibrometry shows that their ear is a two-input system with approximately unity interaural transmission gain at the peak frequency (∼1.6 kHz). Median interaural delays are 260 μs, almost three times larger than predicted from gecko head size, suggesting interaural transmission may be boosted by resonances in the large, open mouth cavity ( Vossen et al. 2010 ). Auditory nerve recordings are sensitive to both interaural time differences (ITD) and interaural level differences (ILD), reflecting the acoustical interactions of direct and indirect sound components at the eardrum. Best ITD and click delays match interaural transmission delays, with a range of 200–500 μs. Inserting a mold in the mouth cavity blocks ITD and ILD sensitivity. Thus the neural response accurately reflects tympanic directionality, and most neurons in the auditory pathway should be directional.

Age-Related and Noise-Induced Hearing Loss

2018 ◽  
pp. 162-188
Author(s):  
Ruili Xie ◽  
Tessa-Jonne F. Ropp ◽  
Michael R. Kasten ◽  
Paul B. Manis
Keyword(s):  
Hearing Loss ◽  
Auditory Nerve ◽  
Transmitter Release ◽  
Time Course ◽  
Functional Change ◽  
Noise Induced Hearing Loss ◽  
Nerve Activity ◽  
Auditory Periphery ◽  
Age Related ◽  
Age Related Hearing Loss

Hearing loss generally occurs in the auditory periphery but leads to changes in the central auditory system. Noise-induced hearing loss (NIHL) and age-related hearing loss (ARHL) affect neurons in the ventral cochlear nucleus (VCN) at both the cellular and systems levels. In response to a decrease in auditory nerve activity associated with hearing loss, the large synaptic endings of the auditory nerve, the endbulbs of Held, undergo simplification of their structure and the volume of the postsynaptic bushy neurons decreases. A major functional change shared by NIHL and ARHL is the development of asynchronous transmitter release at endbulb synapses during periods of high afferent firing. Compensatory adjustements in transmitter release, including changes in release probability and quantal content, have also been reported. The excitability of the bushy cells undergoes subtle changes in the long-term, although short-term, reversible changes in excitability may also occur. These changes are not consistently observed across all models of hearing loss, suggesting that the time course of hearing loss, and potential developmental effects, may influence endbulb transmission in multiple ways. NIHL can alter the representation of the loudness of tonal stimuli by VCN neurons and is accompanied by changes in spontaneous activity in VCN neurons. However, little is known about the representation of more complex stimuli. The relationship between mechanistic changes in VCN neurons with noise-induced or age-related hearing loss, the accompanying change in sensory coding, and the reversibility of changes with the reintroduction of auditory nerve activity are areas that deserve further thoughtful exploration.

scholarly journals Pairing vagus nerve stimulation with tones drives plasticity across the auditory pathway

2019 ◽  
Vol 122 (2) ◽  
pp. 659-671 ◽  
Author(s):  
Michael S. Borland ◽  
Will A. Vrana ◽  
Nicole A. Moreno ◽  
Elizabeth A. Fogarty ◽  
Elizabeth P. Buell ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Vagus Nerve Stimulation ◽  
Primary Auditory Cortex ◽  
Auditory Pathway ◽  
Neural Responses ◽  
Tone Frequency ◽  
Auditory Field ◽  
Paired Tone

Previous studies have demonstrated that pairing vagus nerve stimulation (VNS) with sounds can enhance the primary auditory cortex (A1) response to the paired sound. The neural response to sounds following VNS-sound pairing in other subcortical and cortical auditory fields has not been documented. We predicted that VNS-tone pairing would increase neural responses to the paired tone frequency across the auditory pathway. In this study, we paired VNS with the presentation of a 9-kHz tone 300 times a day for 20 days. We recorded neural responses to tones from 2,950 sites in the inferior colliculus (IC), A1, anterior auditory field (AAF), and posterior auditory field (PAF) 24 h after the last pairing session in anesthetized rats. We found that VNS-tone pairing increased the percentage of IC, A1, AAF, and PAF that responds to the paired tone frequency. Across all tested auditory fields, the response strength to tones was strengthened in VNS-tone paired rats compared with control rats. VNS-tone pairing reduced spontaneous activity, frequency selectivity, and response threshold across the auditory pathway. This is the first study to document both cortical and subcortical plasticity following VNS-sound pairing. Our findings suggest that VNS paired with sound presentation is an effective method to enhance auditory processing. NEW & NOTEWORTHY Previous studies have reported primary auditory cortex plasticity following vagus nerve stimulation (VNS) paired with a sound. This study extends previous findings by documenting that fields across the auditory pathway are altered by VNS-tone pairing. VNS-tone pairing increases the percentage of each field that responds to the paired tone frequency. This is the first study to document both cortical and subcortical plasticity following VNS-sound pairing.

Auditory Imagery Modulates Frequency-specific Areas in the Human Auditory Cortex

2013 ◽  
Vol 25 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Jihoon Oh ◽  
Jae Hyung Kwon ◽  
Po Song Yang ◽  
Jaeseung Jeong
Keyword(s):  
Auditory Cortex ◽  
High Frequency ◽  
Low Frequency ◽  
Primary Auditory Cortex ◽  
Auditory Imagery ◽  
Neural Responses ◽  
Top Down ◽  
Visual Areas ◽  
Control Functional ◽  
Response Area

Neural responses in early sensory areas are influenced by top–down processing. In the visual system, early visual areas have been shown to actively participate in top–down processing based on their topographical properties. Although it has been suggested that the auditory cortex is involved in top–down control, functional evidence of topographic modulation is still lacking. Here, we show that mental auditory imagery for familiar melodies induces significant activation in the frequency-responsive areas of the primary auditory cortex (PAC). This activation is related to the characteristics of the imagery: when subjects were asked to imagine high-frequency melodies, we observed increased activation in the high- versus low-frequency response area; when the subjects were asked to imagine low-frequency melodies, the opposite was observed. Furthermore, we found that A1 is more closely related to the observed frequency-related modulation than R in tonotopic subfields of the PAC. Our findings suggest that top–down processing in the auditory cortex relies on a mechanism similar to that used in the perception of external auditory stimuli, which is comparable to early visual systems.

scholarly journals The time-course of cortical responses to speech revealed by fast optical imaging

2018 ◽  
Vol 184 ◽  
pp. 32-42 ◽  
Author(s):  
Joseph C. Toscano ◽  
Nathaniel D. Anderson ◽  
Monica Fabiani ◽  
Gabriele Gratton ◽  
Susan M. Garnsey
Keyword(s):  
Optical Imaging ◽  
Time Course ◽  
Cortical Responses

Neural Responses in Primary Auditory Cortex Mimic Psychophysical, Across-Frequency-Channel, Gap-Detection Thresholds

2000 ◽  
Vol 84 (3) ◽  
pp. 1453-1463 ◽  
Author(s):  
Jos J. Eggermont
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Primary Auditory Cortex ◽  
Noise Burst ◽  
Gap Detection ◽  
Frequency Content ◽  
Neural Responses ◽  
Frequency Channel ◽  
Interval Representations ◽  
Onset Response

Responses of single- and multi-units in primary auditory cortex were recorded for gap-in-noise stimuli for different durations of the leading noise burst. Both firing rate and inter-spike interval representations were evaluated. The minimum detectable gap decreased in exponential fashion with the duration of the leading burst to reach an asymptote for durations of 100 ms. Despite the fact that leading and trailing noise bursts had the same frequency content, the dependence on leading burst duration was correlated with psychophysical estimates of across frequency channel (different frequency content of leading and trailing burst) gap thresholds in humans. The duration of the leading burst plus that of the gap was represented in the all-order inter-spike interval histograms for cortical neurons. The recovery functions for cortical neurons could be modeled on basis of fast synaptic depression and after-hyperpolarization produced by the onset response to the leading noise burst. This suggests that the minimum gap representation in the firing pattern of neurons in primary auditory cortex, and minimum gap detection in behavioral tasks is largely determined by properties intrinsic to those, or potentially subcortical, cells.

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