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Adenis V, Partouche E, Stahl P, Gnansia D, Huetz C, Edeline JM. Asymmetric pulses delivered by a cochlear implant allow a reduction in evoked firing rate and in spatial activation in the guinea pig auditory cortex. Hear Res 2024; 447:109027. [PMID: 38723386 DOI: 10.1016/j.heares.2024.109027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 04/30/2024] [Accepted: 05/02/2024] [Indexed: 05/25/2024]
Abstract
Despite that fact that the cochlear implant (CI) is one of the most successful neuro-prosthetic devices which allows hearing restoration, several aspects still need to be improved. Interactions between stimulating electrodes through current spread occurring within the cochlea drastically limit the number of discriminable frequency channels and thus can ultimately result in poor speech perception. One potential solution relies on the use of new pulse shapes, such as asymmetric pulses, which can potentially reduce the current spread within the cochlea. The present study characterized the impact of changing electrical pulse shapes from the standard biphasic symmetric to the asymmetrical shape by quantifying the evoked firing rate and the spatial activation in the guinea pig primary auditory cortex (A1). At a fixed charge, the firing rate and the spatial activation in A1 decreased by 15 to 25 % when asymmetric pulses were used to activate the auditory nerve fibers, suggesting a potential reduction of the spread of excitation inside the cochlea. A strong "polarity-order" effect was found as the reduction was more pronounced when the first phase of the pulse was cathodic with high amplitude. These results suggest that the use of asymmetrical pulse shapes in clinical settings can potentially reduce the channel interactions in CI users.
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Affiliation(s)
- V Adenis
- Paris-Saclay Institute of Neurosciences (Neuro-PSI), France; CNRS UMR 9197, 91405 Orsay cedex, France; Université Paris-Saclay, 91405 Orsay cedex, France
| | - E Partouche
- Paris-Saclay Institute of Neurosciences (Neuro-PSI), France; CNRS UMR 9197, 91405 Orsay cedex, France; Université Paris-Saclay, 91405 Orsay cedex, France
| | - P Stahl
- Oticon Medical, Vallauris, France
| | | | - C Huetz
- Paris-Saclay Institute of Neurosciences (Neuro-PSI), France; CNRS UMR 9197, 91405 Orsay cedex, France; Université Paris-Saclay, 91405 Orsay cedex, France
| | - J-M Edeline
- Paris-Saclay Institute of Neurosciences (Neuro-PSI), France; CNRS UMR 9197, 91405 Orsay cedex, France; Université Paris-Saclay, 91405 Orsay cedex, France.
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Partouche E, Adenis V, Stahl P, Huetz C, Edeline JM. What Is the Benefit of Ramped Pulse Shapes for Activating Auditory Cortex Neurons? An Electrophysiological Study in an Animal Model of Cochlear Implant. Brain Sci 2023; 13:brainsci13020250. [PMID: 36831793 PMCID: PMC9954719 DOI: 10.3390/brainsci13020250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/19/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
In all commercial cochlear implant (CI) devices, the activation of auditory nerve fibers is performed with rectangular pulses that have two phases of opposite polarity. Recently, several papers proposed that ramped pulse shapes could be an alternative shape for efficiently activating auditory nerve fibers. Here, we investigate whether ramped pulse shapes can activate auditory cortex (ACx) neurons in a more efficient way than the classical rectangular pulses. Guinea pigs were implanted with CI devices and responses of ACx neurons were tested with rectangular pulses and with four ramped pulse shapes, with a first-phase being either cathodic or anodic. The thresholds, i.e., the charge level necessary for obtaining significant cortical responses, were almost systematically lower with ramped pulses than with rectangular pulses. The maximal firing rate (FR) elicited by the ramped pulses was higher than with rectangular pulses. As the maximal FR occurred with lower charge levels, the dynamic range (between threshold and the maximal FR) was not modified. These effects were obtained with cathodic and anodic ramped pulses. By reducing the charge levels required to activate ACx neurons, the ramped pulse shapes should reduce charge consumption and should contribute to more battery-efficient CI devices in the future.
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Affiliation(s)
- Elie Partouche
- Jean-Marc Edeline Paris-Saclay Institute of Neurosciences (Neuro-PSI), CNRS UMR 9197, Universite Paris-Saclay, Campus CEA Saclay, Route de la Rotonde Bâtiment 151, 91400 Saclay, France
| | - Victor Adenis
- Jean-Marc Edeline Paris-Saclay Institute of Neurosciences (Neuro-PSI), CNRS UMR 9197, Universite Paris-Saclay, Campus CEA Saclay, Route de la Rotonde Bâtiment 151, 91400 Saclay, France
| | - Pierre Stahl
- Departement of Scientific and Clinical Research, Oticon Medical, 06220 Vallauris, France
| | - Chloé Huetz
- Jean-Marc Edeline Paris-Saclay Institute of Neurosciences (Neuro-PSI), CNRS UMR 9197, Universite Paris-Saclay, Campus CEA Saclay, Route de la Rotonde Bâtiment 151, 91400 Saclay, France
| | - Jean-Marc Edeline
- Jean-Marc Edeline Paris-Saclay Institute of Neurosciences (Neuro-PSI), CNRS UMR 9197, Universite Paris-Saclay, Campus CEA Saclay, Route de la Rotonde Bâtiment 151, 91400 Saclay, France
- Correspondence:
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Souffi S, Varnet L, Zaidi M, Bathellier B, Huetz C, Edeline JM. Reduction in sound discrimination in noise is related to envelope similarity and not to a decrease in envelope tracking abilities. J Physiol 2023; 601:123-149. [PMID: 36373184 DOI: 10.1113/jp283526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 11/08/2022] [Indexed: 11/15/2022] Open
Abstract
Humans and animals constantly face challenging acoustic environments, such as various background noises, that impair the detection, discrimination and identification of behaviourally relevant sounds. Here, we disentangled the role of temporal envelope tracking in the reduction in neuronal and behavioural discrimination between communication sounds in situations of acoustic degradations. By collecting neuronal activity from six different levels of the auditory system, from the auditory nerve up to the secondary auditory cortex, in anaesthetized guinea-pigs, we found that tracking of slow changes of the temporal envelope is a general functional property of auditory neurons for encoding communication sounds in quiet conditions and in adverse, challenging conditions. Results from a go/no-go sound discrimination task in mice support the idea that the loss of distinct slow envelope cues in noisy conditions impacted the discrimination performance. Together, these results suggest that envelope tracking is potentially a universal mechanism operating in the central auditory system, which allows the detection of any between-stimulus difference in the slow envelope and thus copes with degraded conditions. KEY POINTS: In quiet conditions, envelope tracking in the low amplitude modulation range (<20 Hz) is correlated with the neuronal discrimination between communication sounds as quantified by mutual information from the cochlear nucleus up to the auditory cortex. At each level of the auditory system, auditory neurons retain their abilities to track the communication sound envelopes in situations of acoustic degradation, such as vocoding and the addition of masking noises up to a signal-to-noise ratio of -10 dB. In noisy conditions, the increase in between-stimulus envelope similarity explains the reduction in both behavioural and neuronal discrimination in the auditory system. Envelope tracking can be viewed as a universal mechanism that allows neural and behavioural discrimination as long as the temporal envelope of communication sounds displays some differences.
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Affiliation(s)
- Samira Souffi
- Paris-Saclay Institute of Neuroscience (Neuro-PSI, UMR 9197), CNRS - Université Paris-Saclay, Saclay, France
| | - Léo Varnet
- Laboratoire des systèmes perceptifs, UMR CNRS 8248, Département d'Etudes Cognitives, Ecole Normale Supérieure, Université Paris Sciences & Lettres, Paris, France
| | - Meryem Zaidi
- Paris-Saclay Institute of Neuroscience (Neuro-PSI, UMR 9197), CNRS - Université Paris-Saclay, Saclay, France
| | - Brice Bathellier
- Institut de l'Audition, Institut Pasteur, Université de Paris, INSERM, Paris, France
| | - Chloé Huetz
- Paris-Saclay Institute of Neuroscience (Neuro-PSI, UMR 9197), CNRS - Université Paris-Saclay, Saclay, France
| | - Jean-Marc Edeline
- Paris-Saclay Institute of Neuroscience (Neuro-PSI, UMR 9197), CNRS - Université Paris-Saclay, Saclay, France
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Bishop R, Qureshi F, Yan J. Age-related changes in neuronal receptive fields of primary auditory cortex in frequency, amplitude, and temporal domains. Hear Res 2022; 420:108504. [DOI: 10.1016/j.heares.2022.108504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 03/23/2022] [Accepted: 03/31/2022] [Indexed: 11/25/2022]
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Exposure to 1800 MHz LTE electromagnetic fields under proinflammatory conditions decreases the response strength and increases the acoustic threshold of auditory cortical neurons. Sci Rep 2022; 12:4063. [PMID: 35260711 PMCID: PMC8902282 DOI: 10.1038/s41598-022-07923-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 02/25/2022] [Indexed: 11/09/2022] Open
Abstract
Increased needs for mobile phone communications have raised successive generations (G) of wireless technologies, which could differentially affect biological systems. To test this, we exposed rats to single head-only exposure of a 4G long-term evolution (LTE)-1800 MHz electromagnetic field (EMF) for 2 h. We then assessed the impact on microglial space coverage and electrophysiological neuronal activity in the primary auditory cortex (ACx), under acute neuroinflammation induced by lipopolysaccharide. The mean specific absorption rate in the ACx was 0.5 W/kg. Multiunit recording revealed that LTE-EMF triggered reduction in the response strength to pure tones and to natural vocalizations, together with an increase in acoustic threshold in the low and medium frequencies. Iba1 immunohistochemistry showed no change in the area covered by microglia cell bodies and processes. In healthy rats, the same LTE-exposure induced no change in response strength and acoustic threshold. Our data indicate that acute neuroinflammation sensitizes neuronal responses to LTE-EMF, which leads to an altered processing of acoustic stimuli in the ACx.
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Partouche E, Adenis V, Gnansia D, Stahl P, Edeline JM. Increased Threshold and Reduced Firing Rate of Auditory Cortex Neurons after Cochlear Implant Insertion. Brain Sci 2022; 12:brainsci12020205. [PMID: 35203968 PMCID: PMC8870646 DOI: 10.3390/brainsci12020205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/25/2022] [Accepted: 01/28/2022] [Indexed: 12/10/2022] Open
Abstract
The cochlear implant (CI) is the most successful neuroprosthesis allowing thousands of patients with profound hearing loss to recover speech understanding. Recently, cochlear implants have been proposed to subjects with residual hearing and, in these cases, shorter CIs were implanted. To be successful, it is crucial to preserve the patient’s remaining hearing abilities after the implantation. Here, we quantified the effects of CI insertion on the responses of auditory cortex neurons in anesthetized guinea pigs. The responses of auditory cortex neurons were determined before and after the insertion of a 300 µm diameter CI (six stimulating electrodes, length 6 mm). Immediately after CI insertion there was a 5 to 15 dB increase in the threshold for cortical neurons from the middle to the high frequencies, accompanied by a decrease in the evoked firing rate. Analyzing the characteristic frequency (CF) values revealed that in large number of cases, the CFs obtained after insertion were lower than before. These effects were not detected in the control animals. These results indicate that there is a small but immediate cortical hearing loss after CI insertion, even with short length CIs. Therefore, efforts should be made to minimize the damages during CI insertion to preserve the cortical responses to acoustic stimuli.
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Affiliation(s)
- Elie Partouche
- Paris-Saclay Institute of Neurosciences (Neuro-PSI), CNRS UMR 9197, Universite Paris-Saclay, 91400 Saclay, France; (E.P.); (V.A.)
| | - Victor Adenis
- Paris-Saclay Institute of Neurosciences (Neuro-PSI), CNRS UMR 9197, Universite Paris-Saclay, 91400 Saclay, France; (E.P.); (V.A.)
| | - Dan Gnansia
- Department of Scientific and Clinical Research, Oticon Medical, 06224 Vallauris, France; (D.G.); (P.S.)
| | - Pierre Stahl
- Department of Scientific and Clinical Research, Oticon Medical, 06224 Vallauris, France; (D.G.); (P.S.)
| | - Jean-Marc Edeline
- Paris-Saclay Institute of Neurosciences (Neuro-PSI), CNRS UMR 9197, Universite Paris-Saclay, 91400 Saclay, France; (E.P.); (V.A.)
- Correspondence:
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7
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Souffi S, Nodal FR, Bajo VM, Edeline JM. When and How Does the Auditory Cortex Influence Subcortical Auditory Structures? New Insights About the Roles of Descending Cortical Projections. Front Neurosci 2021; 15:690223. [PMID: 34413722 PMCID: PMC8369261 DOI: 10.3389/fnins.2021.690223] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 06/14/2021] [Indexed: 12/28/2022] Open
Abstract
For decades, the corticofugal descending projections have been anatomically well described but their functional role remains a puzzling question. In this review, we will first describe the contributions of neuronal networks in representing communication sounds in various types of degraded acoustic conditions from the cochlear nucleus to the primary and secondary auditory cortex. In such situations, the discrimination abilities of collicular and thalamic neurons are clearly better than those of cortical neurons although the latter remain very little affected by degraded acoustic conditions. Second, we will report the functional effects resulting from activating or inactivating corticofugal projections on functional properties of subcortical neurons. In general, modest effects have been observed in anesthetized and in awake, passively listening, animals. In contrast, in behavioral tasks including challenging conditions, behavioral performance was severely reduced by removing or transiently silencing the corticofugal descending projections. This suggests that the discriminative abilities of subcortical neurons may be sufficient in many acoustic situations. It is only in particularly challenging situations, either due to the task difficulties and/or to the degraded acoustic conditions that the corticofugal descending connections bring additional abilities. Here, we propose that it is both the top-down influences from the prefrontal cortex, and those from the neuromodulatory systems, which allow the cortical descending projections to impact behavioral performance in reshaping the functional circuitry of subcortical structures. We aim at proposing potential scenarios to explain how, and under which circumstances, these projections impact on subcortical processing and on behavioral responses.
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Affiliation(s)
- Samira Souffi
- Department of Integrative and Computational Neurosciences, Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR CNRS 9197, Paris-Saclay University, Orsay, France
| | - Fernando R Nodal
- Department of Physiology, Anatomy and Genetics, Medical Sciences Division, University of Oxford, Oxford, United Kingdom
| | - Victoria M Bajo
- Department of Physiology, Anatomy and Genetics, Medical Sciences Division, University of Oxford, Oxford, United Kingdom
| | - Jean-Marc Edeline
- Department of Integrative and Computational Neurosciences, Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR CNRS 9197, Paris-Saclay University, Orsay, France
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Robustness to Noise in the Auditory System: A Distributed and Predictable Property. eNeuro 2021; 8:ENEURO.0043-21.2021. [PMID: 33632813 PMCID: PMC7986545 DOI: 10.1523/eneuro.0043-21.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 12/30/2022] Open
Abstract
Background noise strongly penalizes auditory perception of speech in humans or vocalizations in animals. Despite this, auditory neurons are still able to detect communications sounds against considerable levels of background noise. We collected neuronal recordings in cochlear nucleus (CN), inferior colliculus (IC), auditory thalamus, and primary and secondary auditory cortex in response to vocalizations presented either against a stationary or a chorus noise in anesthetized guinea pigs at three signal-to-noise ratios (SNRs; −10, 0, and 10 dB). We provide evidence that, at each level of the auditory system, five behaviors in noise exist within a continuum, from neurons with high-fidelity representations of the signal, mostly found in IC and thalamus, to neurons with high-fidelity representations of the noise, mostly found in CN for the stationary noise and in similar proportions in each structure for the chorus noise. The two cortical areas displayed fewer robust responses than the IC and thalamus. Furthermore, between 21% and 72% of the neurons (depending on the structure) switch categories from one background noise to another, even if the initial assignment of these neurons to a category was confirmed by a severe bootstrap procedure. Importantly, supervised learning pointed out that assigning a recording to one of the five categories can be predicted up to a maximum of 70% based on both the response to signal alone and noise alone.
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Royer J, Huetz C, Occelli F, Cancela JM, Edeline JM. Enhanced Discriminative Abilities of Auditory Cortex Neurons for Pup Calls Despite Reduced Evoked Responses in C57BL/6 Mother Mice. Neuroscience 2020; 453:1-16. [PMID: 33253823 DOI: 10.1016/j.neuroscience.2020.11.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/03/2020] [Accepted: 11/18/2020] [Indexed: 11/30/2022]
Abstract
A fundamental task for the auditory system is to process communication sounds according to their behavioral significance. In many mammalian species, pup calls became more significant for mothers than other conspecific and heterospecific communication sounds. To study the cortical consequences of motherhood on the processing of communication sounds, we recorded neuronal responses in the primary auditory cortex of virgin and mother C57BL/6 mice which had similar ABR thresholds. In mothers, the evoked firing rate in response to pure tones was decreased and the frequency receptive fields were narrower. The responses to pup and adult calls were also reduced but the amount of mutual information (MI) per spike about the pup call's identity was increased in mother mice. The response latency to pup and adult calls was significantly shorter in mothers. Despite similarly decreased responses to guinea pig whistles, the response latency, and the MI per spike did not differ between virgins and mothers for these heterospecific vocalizations. Noise correlations between cortical recordings were decreased in mothers, suggesting that the firing rate of distant neurons was more independent from each other. Together, these results indicate that in the most commonly used mouse strain for behavioral studies, the discrimination of pup calls by auditory cortex neurons is more efficient during motherhood.
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Affiliation(s)
- Juliette Royer
- Université Paris-Saclay, CNRS UMR 9197, Institut des neurosciences Paris-Saclay, 91190 Gif-sur-Yvette, France; Institut des neurosciences Paris-Saclay, CNRS, 91190 Gif-sur-Yvette, France
| | - Chloé Huetz
- Université Paris-Saclay, CNRS UMR 9197, Institut des neurosciences Paris-Saclay, 91190 Gif-sur-Yvette, France; Institut des neurosciences Paris-Saclay, CNRS, 91190 Gif-sur-Yvette, France
| | - Florian Occelli
- Université Paris-Saclay, CNRS UMR 9197, Institut des neurosciences Paris-Saclay, 91190 Gif-sur-Yvette, France; Institut des neurosciences Paris-Saclay, CNRS, 91190 Gif-sur-Yvette, France
| | - José-Manuel Cancela
- Université Paris-Saclay, CNRS UMR 9197, Institut des neurosciences Paris-Saclay, 91190 Gif-sur-Yvette, France; Institut des neurosciences Paris-Saclay, CNRS, 91190 Gif-sur-Yvette, France
| | - Jean-Marc Edeline
- Université Paris-Saclay, CNRS UMR 9197, Institut des neurosciences Paris-Saclay, 91190 Gif-sur-Yvette, France; Institut des neurosciences Paris-Saclay, CNRS, 91190 Gif-sur-Yvette, France.
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Noise-Sensitive But More Precise Subcortical Representations Coexist with Robust Cortical Encoding of Natural Vocalizations. J Neurosci 2020; 40:5228-5246. [PMID: 32444386 DOI: 10.1523/jneurosci.2731-19.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 05/08/2020] [Accepted: 05/15/2020] [Indexed: 01/30/2023] Open
Abstract
Humans and animals maintain accurate sound discrimination in the presence of loud sources of background noise. It is commonly assumed that this ability relies on the robustness of auditory cortex responses. However, only a few attempts have been made to characterize neural discrimination of communication sounds masked by noise at each stage of the auditory system and to quantify the noise effects on the neuronal discrimination in terms of alterations in amplitude modulations. Here, we measured neural discrimination between communication sounds masked by a vocalization-shaped stationary noise from multiunit responses recorded in the cochlear nucleus, inferior colliculus, auditory thalamus, and primary and secondary auditory cortex at several signal-to-noise ratios (SNRs) in anesthetized male or female guinea pigs. Masking noise decreased sound discrimination of neuronal populations in each auditory structure, but collicular and thalamic populations showed better performance than cortical populations at each SNR. In contrast, in each auditory structure, discrimination by neuronal populations was slightly decreased when tone-vocoded vocalizations were tested. These results shed new light on the specific contributions of subcortical structures to robust sound encoding, and suggest that the distortion of slow amplitude modulation cues conveyed by communication sounds is one of the factors constraining the neuronal discrimination in subcortical and cortical levels.SIGNIFICANCE STATEMENT Dissecting how auditory neurons discriminate communication sounds in noise is a major goal in auditory neuroscience. Robust sound coding in noise is often viewed as a specific property of cortical networks, although this remains to be demonstrated. Here, we tested the discrimination performance of neuronal populations at five levels of the auditory system in response to conspecific vocalizations masked by noise. In each acoustic condition, subcortical neurons better discriminated target vocalizations than cortical ones and in each structure, the reduction in discrimination performance was related to the reduction in slow amplitude modulation cues.
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Parthasarathy A, Bartlett EL, Kujawa SG. Age-related Changes in Neural Coding of Envelope Cues: Peripheral Declines and Central Compensation. Neuroscience 2019; 407:21-31. [DOI: 10.1016/j.neuroscience.2018.12.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 12/22/2022]
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12
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Souza P, Hoover E. The Physiologic and Psychophysical Consequences of Severe-to-Profound Hearing Loss. Semin Hear 2018; 39:349-363. [PMID: 30443103 DOI: 10.1055/s-0038-1670698] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Substantial loss of cochlear function is required to elevate pure-tone thresholds to the severe hearing loss range; yet, individuals with severe or profound hearing loss continue to rely on hearing for communication. Despite the impairment, sufficient information is encoded at the periphery to make acoustic hearing a viable option. However, the probability of significant cochlear and/or neural damage associated with the loss has consequences for sound perception and speech recognition. These consequences include degraded frequency selectivity, which can be assessed with tests including psychoacoustic tuning curves and broadband rippled stimuli. Because speech recognition depends on the ability to resolve frequency detail, a listener with severe hearing loss is likely to have impaired communication in both quiet and noisy environments. However, the extent of the impairment varies widely among individuals. A better understanding of the fundamental abilities of listeners with severe and profound hearing loss and the consequences of those abilities for communication can support directed treatment options in this population.
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Affiliation(s)
- Pamela Souza
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, Illinois
| | - Eric Hoover
- Department of Hearing and Speech Sciences, University of Maryland, Baltimore, Maryland
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13
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Adenis V, Gourévitch B, Mamelle E, Recugnat M, Stahl P, Gnansia D, Nguyen Y, Edeline JM. ECAP growth function to increasing pulse amplitude or pulse duration demonstrates large inter-animal variability that is reflected in auditory cortex of the guinea pig. PLoS One 2018; 13:e0201771. [PMID: 30071005 PMCID: PMC6072127 DOI: 10.1371/journal.pone.0201771] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 07/21/2018] [Indexed: 12/20/2022] Open
Abstract
Despite remarkable advances made to ameliorate how cochlear implants process the acoustic environment, many improvements can still be made. One of most fundamental questions concerns a strategy to simulate an increase in sound intensity. Psychoacoustic studies indicated that acting on either the current, or the duration of the stimulating pulses leads to perception of changes in how loud the sound is. The present study compared the growth function of electrically evoked Compound Action Potentials (eCAP) of the 8th nerve using these two strategies to increase electrical charges (and potentially to increase the sound intensity). Both with chronically (experiment 1) or acutely (experiment 2) implanted guinea pigs, only a few differences were observed between the mean eCAP amplitude growth functions obtained with the two strategies. However, both in chronic and acute experiments, many animals showed larger increases of eCAP amplitude with current increase, whereas some animals showed larger of eCAP amplitude with duration increase, and other animals show no difference between either approaches. This indicates that the parameters allowing the largest increase in eCAP amplitude considerably differ between subjects. In addition, there was a significant correlation between the strength of neuronal firing rate in auditory cortex and the effect of these two strategies on the eCAP amplitude. This suggests that pre-selecting only one strategy for recruiting auditory nerve fibers in a given subject might not be appropriate for all human subjects.
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Affiliation(s)
- Victor Adenis
- Paris-Saclay Institute of Neurosciences (Neuro-PSI) Université Paris-Sud, Orsay, France
- CNRS UMR 9197, Orsay, France
- Université Paris-Saclay, Orsay, France
| | - Boris Gourévitch
- Paris-Saclay Institute of Neurosciences (Neuro-PSI) Université Paris-Sud, Orsay, France
- CNRS UMR 9197, Orsay, France
- Université Paris-Saclay, Orsay, France
| | | | | | | | | | - Yann Nguyen
- INSERM UMR-S-1159, Paris, France
- Université Paris-VI, Paris, France
| | - Jean-Marc Edeline
- Paris-Saclay Institute of Neurosciences (Neuro-PSI) Université Paris-Sud, Orsay, France
- CNRS UMR 9197, Orsay, France
- Université Paris-Saclay, Orsay, France
- * E-mail:
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14
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Occelli F, Lameth J, Adenis V, Huetz C, Lévêque P, Jay TM, Edeline JM, Mallat M. A Single Exposure to GSM-1800 MHz Signals in the Course of an Acute Neuroinflammatory Reaction can Alter Neuronal Responses and Microglial Morphology in the Rat Primary Auditory Cortex. Neuroscience 2018; 385:11-24. [DOI: 10.1016/j.neuroscience.2018.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 05/10/2018] [Accepted: 06/01/2018] [Indexed: 12/21/2022]
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