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Williams IR, Ryugo DK. Bilateral and symmetric glycinergic and glutamatergic projections from the LSO to the IC in the CBA/CaH mouse. Front Neural Circuits 2024; 18:1430598. [PMID: 39184455 PMCID: PMC11341401 DOI: 10.3389/fncir.2024.1430598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Accepted: 07/10/2024] [Indexed: 08/27/2024] Open
Abstract
Auditory space has been conceptualized as a matrix of systematically arranged combinations of binaural disparity cues that arise in the superior olivary complex (SOC). The computational code for interaural time and intensity differences utilizes excitatory and inhibitory projections that converge in the inferior colliculus (IC). The challenge is to determine the neural circuits underlying this convergence and to model how the binaural cues encode location. It has been shown that midbrain neurons are largely excited by sound from the contralateral ear and inhibited by sound leading at the ipsilateral ear. In this context, ascending projections from the lateral superior olive (LSO) to the IC have been reported to be ipsilaterally glycinergic and contralaterally glutamatergic. This study used CBA/CaH mice (3-6 months old) and applied unilateral retrograde tracing techniques into the IC in conjunction with immunocytochemical methods with glycine and glutamate transporters (GlyT2 and vGLUT2, respectively) to analyze the projection patterns from the LSO to the IC. Glycinergic and glutamatergic neurons were spatially intermixed within the LSO, and both types projected to the IC. For GlyT2 and vGLUT2 neurons, the average percentage of ipsilaterally and contralaterally projecting cells was similar (ANOVA, p = 0.48). A roughly equal number of GlyT2 and vGLUT2 neurons did not project to the IC. The somatic size and shape of these neurons match the descriptions of LSO principal cells. A minor but distinct population of small (< 40 μm2) neurons that labeled for GlyT2 did not project to the IC; these cells emerge as candidates for inhibitory local circuit neurons. Our findings indicate a symmetric and bilateral projection of glycine and glutamate neurons from the LSO to the IC. The differences between our results and those from previous studies suggest that species and habitat differences have a significant role in mechanisms of binaural processing and highlight the importance of research methods and comparative neuroscience. These data will be important for modeling how excitatory and inhibitory systems converge to create auditory space in the CBA/CaH mouse.
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Affiliation(s)
- Isabella R. Williams
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
- School of Medical Sciences, University of New South Wales, Kensington, NSW, Australia
| | - David K. Ryugo
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
- School of Medical Sciences, University of New South Wales, Kensington, NSW, Australia
- Department of Otolaryngology, Head, Neck and Skull Base Surgery, St. Vincent’s Hospital, Darlinghurst, NSW, Australia
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2
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Ashida G, Wang T, Kretzberg J. Integrate-and-fire-type models of the lateral superior olive. PLoS One 2024; 19:e0304832. [PMID: 38900820 PMCID: PMC11189240 DOI: 10.1371/journal.pone.0304832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 05/20/2024] [Indexed: 06/22/2024] Open
Abstract
Neurons of the lateral superior olive (LSO) in the auditory brainstem play a fundamental role in binaural sound localization. Previous theoretical studies developed various types of neuronal models to study the physiological functions of the LSO. These models were usually tuned to a small set of physiological data with specific aims in mind. Therefore, it is unclear whether and how they can be related to each other, how widely applicable they are, and which model is suitable for what purposes. In this study, we address these questions for six different single-compartment integrate-and-fire (IF) type LSO models. The models are divided into two groups depending on their subthreshold responses: passive (linear) models with only the leak conductance and active (nonlinear) models with an additional low-voltage-activated potassium conductance that is prevalent among the auditory system. Each of these two groups is further subdivided into three subtypes according to the spike generation mechanism: one with simple threshold-crossing detection and voltage reset, one with threshold-crossing detection plus a current to mimic spike shapes, and one with a depolarizing exponential current for spiking. In our simulations, all six models were driven by identical synaptic inputs and calibrated with common criteria for binaural tuning. The resulting spike rates of the passive models were higher for intensive inputs and lower for temporally structured inputs than those of the active models, confirming the active function of the potassium current. Within each passive or active group, the simulated responses resembled each other, regardless of the spike generation types. These results, in combination with the analysis of computational costs, indicate that an active IF model is more suitable than a passive model for accurately reproducing temporal coding of LSO. The simulation of realistic spike shapes with an extended spiking mechanism added relatively small computational costs.
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Affiliation(s)
- Go Ashida
- Faculty 6, Department of Neuroscience, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Cluster of Excellence "Hearing4all", Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Tiezhi Wang
- Faculty 6, Department of Neuroscience, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Faculty 6, Department of Health Services Research, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Jutta Kretzberg
- Faculty 6, Department of Neuroscience, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Cluster of Excellence "Hearing4all", Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
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3
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Maraslioglu-Sperber A, Pizzi E, Fisch JO, Kattler K, Ritter T, Friauf E. Molecular and functional profiling of cell diversity and identity in the lateral superior olive, an auditory brainstem center with ascending and descending projections. Front Cell Neurosci 2024; 18:1354520. [PMID: 38846638 PMCID: PMC11153811 DOI: 10.3389/fncel.2024.1354520] [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: 12/12/2023] [Accepted: 03/15/2024] [Indexed: 06/09/2024] Open
Abstract
The lateral superior olive (LSO), a prominent integration center in the auditory brainstem, contains a remarkably heterogeneous population of neurons. Ascending neurons, predominantly principal neurons (pLSOs), process interaural level differences for sound localization. Descending neurons (lateral olivocochlear neurons, LOCs) provide feedback into the cochlea and are thought to protect against acoustic overload. The molecular determinants of the neuronal diversity in the LSO are largely unknown. Here, we used patch-seq analysis in mice at postnatal days P10-12 to classify developing LSO neurons according to their functional and molecular profiles. Across the entire sample (n = 86 neurons), genes involved in ATP synthesis were particularly highly expressed, confirming the energy expenditure of auditory neurons. Two clusters were identified, pLSOs and LOCs. They were distinguished by 353 differentially expressed genes (DEGs), most of which were novel for the LSO. Electrophysiological analysis confirmed the transcriptomic clustering. We focused on genes affecting neuronal input-output properties and validated some of them by immunohistochemistry, electrophysiology, and pharmacology. These genes encode proteins such as osteopontin, Kv11.3, and Kvβ3 (pLSO-specific), calcitonin-gene-related peptide (LOC-specific), or Kv7.2 and Kv7.3 (no DEGs). We identified 12 "Super DEGs" and 12 genes showing "Cluster similarity." Collectively, we provide fundamental and comprehensive insights into the molecular composition of individual ascending and descending neurons in the juvenile auditory brainstem and how this may relate to their specific functions, including developmental aspects.
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Affiliation(s)
- Ayse Maraslioglu-Sperber
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Erika Pizzi
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Jonas O. Fisch
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Kathrin Kattler
- Genetics/Epigenetics Group, Department of Biological Sciences, Saarland University, Saarbrücken, Germany
| | - Tamara Ritter
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
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4
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Anderson SR, Burg E, Suveg L, Litovsky RY. Review of Binaural Processing With Asymmetrical Hearing Outcomes in Patients With Bilateral Cochlear Implants. Trends Hear 2024; 28:23312165241229880. [PMID: 38545645 PMCID: PMC10976506 DOI: 10.1177/23312165241229880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 04/01/2024] Open
Abstract
Bilateral cochlear implants (BiCIs) result in several benefits, including improvements in speech understanding in noise and sound source localization. However, the benefit bilateral implants provide among recipients varies considerably across individuals. Here we consider one of the reasons for this variability: difference in hearing function between the two ears, that is, interaural asymmetry. Thus far, investigations of interaural asymmetry have been highly specialized within various research areas. The goal of this review is to integrate these studies in one place, motivating future research in the area of interaural asymmetry. We first consider bottom-up processing, where binaural cues are represented using excitation-inhibition of signals from the left ear and right ear, varying with the location of the sound in space, and represented by the lateral superior olive in the auditory brainstem. We then consider top-down processing via predictive coding, which assumes that perception stems from expectations based on context and prior sensory experience, represented by cascading series of cortical circuits. An internal, perceptual model is maintained and updated in light of incoming sensory input. Together, we hope that this amalgamation of physiological, behavioral, and modeling studies will help bridge gaps in the field of binaural hearing and promote a clearer understanding of the implications of interaural asymmetry for future research on optimal patient interventions.
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Affiliation(s)
- Sean R. Anderson
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical School, Aurora, CO, USA
| | - Emily Burg
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lukas Suveg
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Ruth Y. Litovsky
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI, USA
- Department of Surgery, Division of Otolaryngology, University of Wisconsin-Madison, Madison, WI, USA
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5
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Weingarten DJ, Sebastian E, Winkelhoff J, Patschull-Keiner N, Fischer AU, Wadle SL, Friauf E, Hirtz JJ. An inhibitory glycinergic projection from the cochlear nucleus to the lateral superior olive. Front Neural Circuits 2023; 17:1307283. [PMID: 38107610 PMCID: PMC10722231 DOI: 10.3389/fncir.2023.1307283] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/10/2023] [Indexed: 12/19/2023] Open
Abstract
Auditory brainstem neurons in the lateral superior olive (LSO) receive excitatory input from the ipsilateral cochlear nucleus (CN) and inhibitory transmission from the contralateral CN via the medial nucleus of the trapezoid body (MNTB). This circuit enables sound localization using interaural level differences. Early studies have observed an additional inhibitory input originating from the ipsilateral side. However, many of its details, such as its origin, remained elusive. Employing electrical and optical stimulation of afferents in acute mouse brainstem slices and anatomical tracing, we here describe a glycinergic projection to LSO principal neurons that originates from the ipsilateral CN. This inhibitory synaptic input likely mediates inhibitory sidebands of LSO neurons in response to acoustic stimulation.
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Affiliation(s)
- Dennis J. Weingarten
- Animal Physiology Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Eva Sebastian
- Physiology of Neuronal Networks Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Jennifer Winkelhoff
- Animal Physiology Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
- Physiology of Neuronal Networks Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Nadine Patschull-Keiner
- Animal Physiology Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Alexander U. Fischer
- Animal Physiology Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Simon L. Wadle
- Physiology of Neuronal Networks Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Jan J. Hirtz
- Physiology of Neuronal Networks Group, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany
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6
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Haragopal H, Mellott JG, Dhar M, Kanel A, Mafi A, Tokar N, Winters BD. Tonotopic distribution and inferior colliculus projection pattern of inhibitory and excitatory cell types in the lateral superior olive of mice. J Comp Neurol 2023; 531:1381-1388. [PMID: 37436768 DOI: 10.1002/cne.25515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/26/2023] [Accepted: 06/10/2023] [Indexed: 07/13/2023]
Abstract
The principal neurons (PNs) of the lateral superior olive nucleus (LSO) are an important component of mammalian brainstem circuits that compare activity between the two ears and extract intensity and timing differences used for sound localization. There are two LSO PN transmitter types, glycinergic and glutamatergic, which also have different ascending projection patterns to the inferior colliculus (IC). Glycinergic LSO PNs project ipsilaterally while glutamatergic one's projections vary in laterality by species. In animals with good low-frequency hearing (<3 kHz) such as cats and gerbils, glutamatergic LSO PNs have both ipsilateral and contralateral projections; however, rats that lack this ability only have the contralateral pathway. Additionally, in gerbils, the glutamatergic ipsilateral projecting LSO PNs are biased to the low-frequency limb of the LSO suggesting this pathway may be an adaptation for low-frequency hearing. To further test this premise, we examined the distribution and IC projection pattern of LSO PNs in another high-frequency specialized species using mice by combining in situ hybridization and retrograde tracer injections. We observed no overlap between glycinergic and glutamatergic LSO PNs confirming they are distinct cell populations in mice as well. We found that mice also lack the ipsilateral glutamatergic projection from LSO to IC and that their LSO PN types do not exhibit pronounced tonotopic biases. These data provide insights into the cellular organization of the superior olivary complex and its output to higher processing centers that may underlie functional segregation of information.
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Affiliation(s)
- Hariprakash Haragopal
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Jeffrey G Mellott
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, Ohio, USA
- Brain Health Research Institute, Kent State University, Kent, Ohio, USA
| | - Matasha Dhar
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Alinea Kanel
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Amir Mafi
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Nick Tokar
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Bradley D Winters
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, Ohio, USA
- Brain Health Research Institute, Kent State University, Kent, Ohio, USA
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7
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Ying R, Hamlette L, Nikoobakht L, Balaji R, Miko N, Caras ML. Organization of orbitofrontal-auditory pathways in the Mongolian gerbil. J Comp Neurol 2023; 531:1459-1481. [PMID: 37477903 PMCID: PMC10529810 DOI: 10.1002/cne.25525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/11/2023] [Accepted: 06/26/2023] [Indexed: 07/22/2023]
Abstract
Sound perception is highly malleable, rapidly adjusting to the acoustic environment and behavioral demands. This flexibility is the result of ongoing changes in auditory cortical activity driven by fluctuations in attention, arousal, or prior expectations. Recent work suggests that the orbitofrontal cortex (OFC) may mediate some of these rapid changes, but the anatomical connections between the OFC and the auditory system are not well characterized. Here, we used virally mediated fluorescent tracers to map the projection from OFC to the auditory midbrain, thalamus, and cortex in a classic animal model for auditory research, the Mongolian gerbil (Meriones unguiculatus). We observed no connectivity between the OFC and the auditory midbrain, and an extremely sparse connection between the dorsolateral OFC and higher order auditory thalamic regions. In contrast, we observed a robust connection between the ventral and medial subdivisions of the OFC and the auditory cortex, with a clear bias for secondary auditory cortical regions. OFC axon terminals were found in all auditory cortical lamina but were significantly more concentrated in the infragranular layers. Tissue-clearing and lightsheet microscopy further revealed that auditory cortical-projecting OFC neurons send extensive axon collaterals throughout the brain, targeting both sensory and non-sensory regions involved in learning, decision-making, and memory. These findings provide a more detailed map of orbitofrontal-auditory connections and shed light on the possible role of the OFC in supporting auditory cognition.
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Affiliation(s)
- Rose Ying
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland, 20742
- Department of Biology, University of Maryland, College Park, Maryland, 20742
- Center for Comparative and Evolutionary Biology of Hearing, University of Maryland, College Park, Maryland, 20742
| | - Lashaka Hamlette
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Laudan Nikoobakht
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Rakshita Balaji
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Nicole Miko
- Department of Biology, University of Maryland, College Park, Maryland, 20742
| | - Melissa L. Caras
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland, 20742
- Department of Biology, University of Maryland, College Park, Maryland, 20742
- Center for Comparative and Evolutionary Biology of Hearing, University of Maryland, College Park, Maryland, 20742
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8
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Sammeth CA, Brown AD, Greene NT, Tollin DJ. Interaural frequency mismatch jointly modulates neural brainstem binaural interaction and behavioral interaural time difference sensitivity in humans. Hear Res 2023; 437:108839. [PMID: 37429100 PMCID: PMC10529080 DOI: 10.1016/j.heares.2023.108839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 06/12/2023] [Accepted: 07/04/2023] [Indexed: 07/12/2023]
Abstract
The binaural interaction component (BIC) of the auditory brainstem response (ABR) is the difference obtained after subtracting the sum of right and left ear ABRs from binaurally evoked ABRs. The BIC has attracted interest as a biomarker of binaural processing abilities. Best binaural processing is presumed to require spectrally-matched inputs at the two ears, but peripheral pathology and/or impacts of hearing devices can lead to mismatched inputs. Such mismatching can degrade behavioral sensitivity to interaural time difference (ITD) cues, but might be detected using the BIC. Here, we examine the effect of interaural frequency mismatch (IFM) on BIC and behavioral ITD sensitivity in audiometrically normal adult human subjects (both sexes). Binaural and monaural ABRs were recorded and BICs computed from subjects in response to narrowband tones. Left ear stimuli were fixed at 4000 Hz while right ear stimuli varied over a ∼2-octave range (re: 4000 Hz). Separately, subjects performed psychophysical lateralization tasks using the same stimuli to determine ITD discrimination thresholds jointly as a function of IFM and sound level. Results demonstrated significant effects of IFM on BIC amplitudes, with lower amplitudes in mismatched conditions than frequency-matched. Behavioral ITD discrimination thresholds were elevated at mismatched frequencies and lower sound levels, but also more sharply modulated by IFM at lower sound levels. Combinations of ITD, IFM and overall sound level that resulted in fused and lateralized percepts were bound by the empirically-measured BIC, and also by model predictions simulated using an established computational model of the brainstem circuit thought to generate the BIC.
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Affiliation(s)
- Carol A Sammeth
- Department of Physiology and Biophysics, University of Colorado School of Medicine, RC1-N: Rm 7106, 12800 E. 19th Avenue, Aurora, CO 80045, USA
| | - Andrew D Brown
- Department of Speech and Hearing Sciences, University of Washington, Seattle, WA 98105, USA
| | - Nathaniel T Greene
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Daniel J Tollin
- Department of Physiology and Biophysics, University of Colorado School of Medicine, RC1-N: Rm 7106, 12800 E. 19th Avenue, Aurora, CO 80045, USA; Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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9
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Wei L, Verschooten E, Joris PX. Enhancement of phase-locking in rodents. II. An axonal recording study in chinchilla. J Neurophysiol 2023; 130:751-767. [PMID: 37609701 DOI: 10.1152/jn.00474.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 08/07/2023] [Accepted: 08/15/2023] [Indexed: 08/24/2023] Open
Abstract
The trapezoid body (TB) contains axons of neurons residing in the anteroventral cochlear nucleus (AVCN) that provide excitatory and inhibitory inputs to the main monaural and binaural nuclei in the superior olivary complex (SOC). To understand the monaural and binaural response properties of neurons in the medial and lateral superior olive (MSO and LSO), it is important to characterize the temporal firing properties of these inputs. Because of its exceptional low-frequency hearing, the chinchilla (Chinchilla lanigera) is one of the widely used small animal models for studies of hearing. However, the characterization of the output of its ventral cochlear nucleus to the nuclei of the SOC is fragmentary. We obtained responses of TB axons to stimuli typically used in binaural studies and compared these responses to those of auditory nerve (AN) fibers, with a focus on temporal coding. We found enhancement of phase-locking and entrainment, i.e., the ability of a neuron to fire action potentials at a certain stimulus phase for nearly every stimulus period, in TB axons relative to AN fibers. Enhancement in phase-locking and entrainment are quantitatively more modest than in the cat but greater than in the gerbil. As in these species, these phenomena occur not only in low-frequency neurons stimulated at their characteristic frequency but also in neurons tuned to higher frequencies when stimulated with low-frequency tones, to which complex phase-locking behavior with multiple modes of firing per stimulus cycle is frequently observed.NEW & NOTEWORTHY The sensitivity of neurons to small time differences in sustained sounds to both ears is important for binaural hearing, and this sensitivity is critically dependent on phase-locking in the monaural pathways. Although studies in cat showed a marked improvement in phase-locking from the peripheral to the central auditory nervous system, the evidence in rodents is mixed. Here, we recorded from AN and TB of chinchilla and found temporal enhancement, though more limited than in cat.
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Affiliation(s)
- Liting Wei
- Laboratory of Auditory Neurophysiology, KU Leuven, Leuven, Belgium
| | - Eric Verschooten
- Laboratory of Auditory Neurophysiology, KU Leuven, Leuven, Belgium
| | - Philip X Joris
- Laboratory of Auditory Neurophysiology, KU Leuven, Leuven, Belgium
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10
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Capshaw G, Brown AD, Peña JL, Carr CE, Christensen-Dalsgaard J, Tollin DJ, Womack MC, McCullagh EA. The continued importance of comparative auditory research to modern scientific discovery. Hear Res 2023; 433:108766. [PMID: 37084504 PMCID: PMC10321136 DOI: 10.1016/j.heares.2023.108766] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/23/2023] [Accepted: 04/05/2023] [Indexed: 04/23/2023]
Abstract
A rich history of comparative research in the auditory field has afforded a synthetic view of sound information processing by ears and brains. Some organisms have proven to be powerful models for human hearing due to fundamental similarities (e.g., well-matched hearing ranges), while others feature intriguing differences (e.g., atympanic ears) that invite further study. Work across diverse "non-traditional" organisms, from small mammals to avians to amphibians and beyond, continues to propel auditory science forward, netting a variety of biomedical and technological advances along the way. In this brief review, limited primarily to tetrapod vertebrates, we discuss the continued importance of comparative studies in hearing research from the periphery to central nervous system with a focus on outstanding questions such as mechanisms for sound capture, peripheral and central processing of directional/spatial information, and non-canonical auditory processing, including efferent and hormonal effects.
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Affiliation(s)
- Grace Capshaw
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Andrew D Brown
- Department of Speech and Hearing Sciences, University of Washington, Seattle, WA 98105, USA
| | - José L Peña
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Catherine E Carr
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | | | - Daniel J Tollin
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Department of Otolaryngology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Molly C Womack
- Department of Biology, Utah State University, Logan, UT 84322, USA.
| | - Elizabeth A McCullagh
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74078, USA.
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11
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de Cheveigné A. Why is the perceptual octave stretched? An account based on mismatched time constants within the auditory brainstem. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 153:2600. [PMID: 37129672 DOI: 10.1121/10.0017978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/12/2023] [Indexed: 05/03/2023]
Abstract
This paper suggests an explanation for listeners' greater tolerance to positive than negative mistuning of the higher tone within an octave pair. It hypothesizes a neural circuit tuned to cancel the lower tone that also cancels the higher tone if that tone is in tune. Imperfect cancellation is the cue to mistuning of the octave. The circuit involves two neural pathways, one delayed with respect to the other, that feed a coincidence-sensitive neuron via excitatory and inhibitory synapses. A mismatch between the time constants of these two synapses results in an asymmetry in sensitivity to mismatch. Specifically, if the time constant of the delayed pathway is greater than that of the direct pathway, there is a greater tolerance to positive mistuning than to negative mistuning. The model is directly applicable to the harmonic octave (concurrent tones) but extending it to the melodic octave (successive tones) requires additional assumptions that are discussed. The paper reviews evidence from auditory psychophysics and physiology in favor-or against-this explanation.
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Affiliation(s)
- Alain de Cheveigné
- Laboratoire des Systèmes Perceptifs, Unité Mixte de Recherche 8248, Centre National de la Recherche Scientifique, Paris, France
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12
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Haragopal H, Winters BD. Principal neuron diversity in the murine lateral superior olive supports multiple sound localization strategies and segregation of information in higher processing centers. Commun Biol 2023; 6:432. [PMID: 37076594 PMCID: PMC10115857 DOI: 10.1038/s42003-023-04802-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/04/2023] [Indexed: 04/21/2023] Open
Abstract
Principal neurons (PNs) of the lateral superior olive nucleus (LSO) in the brainstem of mammals compare information between the two ears and enable sound localization on the horizontal plane. The classical view of the LSO is that it extracts ongoing interaural level differences (ILDs). Although it has been known for some time that LSO PNs have intrinsic relative timing sensitivity, recent reports further challenge conventional thinking, suggesting the major function of the LSO is detection of interaural time differences (ITDs). LSO PNs include inhibitory (glycinergic) and excitatory (glutamatergic) neurons which differ in their projection patterns to higher processing centers. Despite these distinctions, intrinsic property differences between LSO PN types have not been explored. The intrinsic cellular properties of LSO PNs are fundamental to how they process and encode information, and ILD/ITD extraction places disparate demands on neuronal properties. Here we examine the ex vivo electrophysiology and cell morphology of inhibitory and excitatory LSO PNs in mice. Although overlapping, properties of inhibitory LSO PNs favor time coding functions while those of excitatory LSO PNs favor integrative level coding. Inhibitory and excitatory LSO PNs exhibit different activation thresholds, potentially providing further means to segregate information in higher processing centers. Near activation threshold, which may be physiologically similar to the sensitive transition point in sound source location for LSO, all LSO PNs exhibit single-spike onset responses that can provide optimal time encoding ability. As stimulus intensity increases, LSO PN firing patterns diverge into onset-burst cells, which can continue to encode timing effectively regardless of stimulus duration, and multi-spiking cells, which can provide robust individually integrable level information. This bimodal response pattern may produce a multi-functional LSO which can encode timing with maximum sensitivity and respond effectively to a wide range of sound durations and relative levels.
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Affiliation(s)
- Hariprakash Haragopal
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Bradley D Winters
- Department of Anatomy and Neurobiology and Hearing Research Group, Northeast Ohio Medical University, Rootstown, OH, USA.
- Brain Health Research Institute, Kent State University, Kent, OH, USA.
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13
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Buck AN, Buchholz S, Schnupp JW, Rosskothen-Kuhl N. Interaural time difference sensitivity under binaural cochlear implant stimulation persists at high pulse rates up to 900 pps. Sci Rep 2023; 13:3785. [PMID: 36882473 PMCID: PMC9992369 DOI: 10.1038/s41598-023-30569-0] [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: 09/01/2022] [Accepted: 02/27/2023] [Indexed: 03/09/2023] Open
Abstract
Spatial hearing remains one of the major challenges for bilateral cochlear implant (biCI) users, and early deaf patients in particular are often completely insensitive to interaural time differences (ITDs) delivered through biCIs. One popular hypothesis is that this may be due to a lack of early binaural experience. However, we have recently shown that neonatally deafened rats fitted with biCIs in adulthood quickly learn to discriminate ITDs as well as their normal hearing litter mates, and perform an order of magnitude better than human biCI users. Our unique behaving biCI rat model allows us to investigate other possible limiting factors of prosthetic binaural hearing, such as the effect of stimulus pulse rate and envelope shape. Previous work has indicated that ITD sensitivity may decline substantially at the high pulse rates often used in clinical practice. We therefore measured behavioral ITD thresholds in neonatally deafened, adult implanted biCI rats to pulse trains of 50, 300, 900 and 1800 pulses per second (pps), with either rectangular or Hanning window envelopes. Our rats exhibited very high sensitivity to ITDs at pulse rates up to 900 pps for both envelope shapes, similar to those in common clinical use. However, ITD sensitivity declined to near zero at 1800 pps, for both Hanning and rectangular windowed pulse trains. Current clinical cochlear implant (CI) processors are often set to pulse rates ≥ 900 pps, but ITD sensitivity in human CI listeners has been reported to decline sharply above ~ 300 pps. Our results suggest that the relatively poor ITD sensitivity seen at > 300 pps in human CI users may not reflect the hard upper limit of biCI ITD performance in the mammalian auditory pathway. Perhaps with training or better CI strategies good binaural hearing may be achievable at pulse rates high enough to allow good sampling of speech envelopes while delivering usable ITDs.
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Affiliation(s)
- Alexa N Buck
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,City University of Hong Kong Shenzhen Research Institute, Shenzhen, China.,Plasticity of Central Auditory Circuits, Institut de l'Audition, Institut Pasteur, Paris, France
| | - Sarah Buchholz
- Neurobiological Research Laboratory, Section of Clinical and Experimental Otology, Department of Oto-Rhino-Laryngology, Faculty of Medicine, Medical Center-University of Freiburg, University of Freiburg, Killianst. 5, 79106, Freiburg im Breisgau, Germany
| | - Jan W Schnupp
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Nicole Rosskothen-Kuhl
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China. .,Neurobiological Research Laboratory, Section of Clinical and Experimental Otology, Department of Oto-Rhino-Laryngology, Faculty of Medicine, Medical Center-University of Freiburg, University of Freiburg, Killianst. 5, 79106, Freiburg im Breisgau, Germany. .,Bernstein Center Freiburg and Faculty of Biology, University of Freiburg, Freiburg, Germany.
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14
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Williams IR, Filimontseva A, Connelly CJ, Ryugo DK. The lateral superior olive in the mouse: Two systems of projecting neurons. Front Neural Circuits 2022; 16:1038500. [PMID: 36338332 PMCID: PMC9630946 DOI: 10.3389/fncir.2022.1038500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 09/29/2022] [Indexed: 01/24/2023] Open
Abstract
The lateral superior olive (LSO) is a key structure in the central auditory system of mammals that exerts efferent control on cochlear sensitivity and is involved in the processing of binaural level differences for sound localization. Understanding how the LSO contributes to these processes requires knowledge about the resident cells and their connections with other auditory structures. We used standard histological stains and retrograde tracer injections into the inferior colliculus (IC) and cochlea in order to characterize two basic groups of neurons: (1) Principal and periolivary (PO) neurons have projections to the IC as part of the ascending auditory pathway; and (2) lateral olivocochlear (LOC) intrinsic and shell efferents have descending projections to the cochlea. Principal and intrinsic neurons are intermixed within the LSO, exhibit fusiform somata, and have disk-shaped dendritic arborizations. The principal neurons have bilateral, symmetric, and tonotopic projections to the IC. The intrinsic efferents have strictly ipsilateral projections, known to be tonotopic from previous publications. PO and shell neurons represent much smaller populations (<10% of principal and intrinsic neurons, respectively), have multipolar somata, reside outside the LSO, and have non-topographic, bilateral projections. PO and shell neurons appear to have widespread projections to their targets that imply a more diffuse modulatory function. The somata and dendrites of principal and intrinsic neurons form a laminar matrix within the LSO and share quantifiably similar alignment to the tonotopic axis. Their restricted projections emphasize the importance of frequency in binaural processing and efferent control for auditory perception. This study addressed and expanded on previous findings of cell types, circuit laterality, and projection tonotopy in the LSO of the mouse.
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Affiliation(s)
- Isabella R. Williams
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia,School of Medical Sciences, University of New South Wales, Kensington, NSW, Australia,*Correspondence: Isabella R. Williams,
| | | | - Catherine J. Connelly
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia,School of Medical Sciences, University of New South Wales, Kensington, NSW, Australia
| | - David K. Ryugo
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia,School of Medical Sciences, University of New South Wales, Kensington, NSW, Australia,Department of Otolaryngology-Head, Neck and Skull Base Surgery, St. Vincent’s Hospital, Darlinghurst, NSW, Australia
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15
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Joris PX. In praise of adventitious sounds. Hear Res 2022; 425:108592. [DOI: 10.1016/j.heares.2022.108592] [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: 10/04/2021] [Revised: 07/13/2022] [Accepted: 07/26/2022] [Indexed: 11/04/2022]
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16
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Müller NIC, Paulußen I, Hofmann LN, Fisch JO, Singh A, Friauf E. Development of synaptic fidelity and action potential robustness at an inhibitory sound localization circuit: effects of otoferlin-related deafness. J Physiol 2022; 600:2461-2497. [PMID: 35439328 DOI: 10.1113/jp280403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 03/30/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Inhibitory glycinergic inputs from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) are involved in sound localization. This brainstem circuit performs reliably throughout life. How such reliability develops is unknown. Here we investigated the role of acoustic experience on the functional maturation of MNTB-LSO inputs at juvenile (postnatal day P11) and young-adult ages (P38) employing deaf mice lacking otoferlin (KO). We analyzed neurotransmission at single MNTB-LSO fibers in acute brainstem slices employing prolonged high-frequency stimulation (1-200 Hz|60 s). At P11, KO inputs still performed normally, as manifested by normal synaptic attenuation, fidelity, replenishment rate, temporal precision, and action potential robustness. Between P11-P38, several synaptic parameters increased substantially in WTs, collectively resulting in high-fidelity and temporally precise neurotransmission. In contrast, maturation of synaptic fidelity was largely absent in KOs after P11. Collectively, reliable neurotransmission at inhibitory MNTB-LSO inputs develops under the guidance of acoustic experience. ABSTRACT Sound localization involves information analysis in the lateral superior olive (LSO), a conspicuous nucleus in the mammalian auditory brainstem. LSO neurons weigh interaural level differences (ILDs) through precise integration of glutamatergic excitation from the cochlear nucleus (CN) and glycinergic inhibition from the medial nucleus of the trapezoid body (MNTB). Sound sources can be localized even during sustained perception, an accomplishment that requires robust neurotransmission. Virtually nothing is known about the sustained performance and the temporal precision of MNTB-LSO inputs after postnatal day (P)12 (time of hearing onset) and whether acoustic experience guides development. Here we performed whole-cell patch-clamp recordings to investigate neurotransmission of single MNTB-LSO fibers upon sustained electrical stimulation (1-200 Hz|60 s) at P11 and P38 in wild-type (WT) and deaf otoferlin (Otof) knock-out (KO) mice. At P11, WT and KO inputs performed remarkably similarly. In WTs, the performance increased drastically between P11-P38, e.g. manifested by an 8 to 11-fold higher replenishment rate (RR) of synaptic vesicles (SVs) and action potential robustness. Together, these changes resulted in reliable and highly precise neurotransmission at frequencies ≤ 100 Hz. In contrast, KO inputs performed similarly at both ages, implying impaired synaptic maturation. Computational modeling confirmed the empirical observations and established a reduced RR per release site for P38 KOs. In conclusion, acoustic experience appears to contribute massively to the development of reliable neurotransmission, thereby forming the basis for effective ILD detection. Collectively, our results provide novel insights into experience-dependent maturation of inhibitory neurotransmission and auditory circuits at the synaptic level. Abstract figure legend MNTB-LSO inputs are a major component of the mammalian auditory brainstem. Reliable neurotransmission at these inputs requires both failure-free conduction of action potentials and robust synaptic transmission. The development of reliable neurotransmission depends crucially on functional hearing, as demonstrated in a time series and by the fact that deafness - upon loss of the protein otoferlin - results in severely impaired synaptic release and replenishment machineries. These findings from animal research may have some implications towards optimizing cochlear implant strategies on newborn humans. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Nicolas I C Müller
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, D-67663, Germany.,Physiology of Neuronal Networks, Department of Biology, University of Kaiserslautern, Kaiserslautern, D-67663, Germany
| | - Isabelle Paulußen
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, D-67663, Germany
| | - Lina N Hofmann
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, D-67663, Germany
| | - Jonas O Fisch
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, D-67663, Germany
| | - Abhyudai Singh
- 3Electrical & Computer Engineering, University of Delaware, Newark, DE, USA
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, D-67663, Germany
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17
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Brughera A, Ballestero JA, McAlpine D. Sensitivity to Envelope Interaural Time Differences: Modeling Auditory Modulation Filtering. J Assoc Res Otolaryngol 2022; 23:35-57. [PMID: 34741225 PMCID: PMC8782955 DOI: 10.1007/s10162-021-00816-0] [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: 09/10/2020] [Accepted: 08/30/2021] [Indexed: 02/03/2023] Open
Abstract
For amplitude-modulated sound, the envelope interaural time difference (ITDENV) is a potential cue for sound-source location. ITDENV is encoded in the lateral superior olive (LSO) of the auditory brainstem, by excitatory-inhibitory (EI) neurons receiving ipsilateral excitation and contralateral inhibition. Between human listeners, sensitivity to ITDENV varies considerably, but ultimately decreases with increasing stimulus carrier frequency, and decreases more strongly with increasing modulation rate. Mechanisms underlying the variation in behavioral sensitivity remain unclear. Here, with increasing carrier frequency (4-10 kHz), as we phenomenologically model the associated decrease in ITDENV sensitivity using arbitrarily fewer neurons consistent across populations, we computationally model the variable sensitivity across human listeners and modulation rates (32-800 Hz) as the decreasing range of membrane frequency responses in LSO neurons. Transposed tones stimulate a bilateral auditory-periphery model, driving model EI neurons where electrical membrane impedance filters the frequency content of inputs driven by amplitude-modulated sound, evoking modulation filtering. Calculated from Fisher information in spike-rate functions of ITDENV, for model EI neuronal populations distinctly reflecting the LSO range in membrane frequency responses, just-noticeable differences in ITDENV collectively reproduce the largest variation in ITDENV sensitivity across human listeners. These slow to fast model populations each generally match the best human ITDENV sensitivity at a progressively higher modulation rate, by membrane-filtering and spike-generation properties producing realistically less than Poisson variance. Non-resonant model EI neurons are also sensitive to interaural intensity differences. With peripheral filters centered between carrier frequency and modulation sideband, fast resonant model EI neurons extend ITDENV sensitivity above 500-Hz modulation.
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Affiliation(s)
- Andrew Brughera
- grid.1004.50000 0001 2158 5405Department of Linguistics, and the Australian Hearing Hub, Macquarie University, Macquarie Park, New South Wales Australia ,grid.189504.10000 0004 1936 7558Department of Biomedical Engineering, Boston University, Boston, MA USA
| | - Jimena A. Ballestero
- Instituto de Fisiología y Biofísica (IFIBIO) Bernardo Houssay, Grupo de Neurociencia de Sistemas, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - David McAlpine
- grid.1004.50000 0001 2158 5405Department of Linguistics, and the Australian Hearing Hub, Macquarie University, Macquarie Park, New South Wales Australia
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18
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Mellott JG, Dhar M, Mafi A, Tokar N, Winters BD. Tonotopic distribution and inferior colliculus projection pattern of inhibitory and excitatory cell types in the lateral superior olive of Mongolian gerbils. J Comp Neurol 2022; 530:506-517. [PMID: 34338321 PMCID: PMC8716415 DOI: 10.1002/cne.25226] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 07/27/2021] [Accepted: 07/29/2021] [Indexed: 02/03/2023]
Abstract
Sound localization critically relies on brainstem neurons that compare information from the two ears. The conventional role of the lateral superior olive (LSO) is extraction of intensity differences; however, it is increasingly clear that relative timing, especially of transients, is also an important function. Cellular diversity within the LSO that is not well understood may underlie its multiple roles. There are glycinergic inhibitory and glutamatergic excitatory principal neurons in the LSO, however, there is some disagreement regarding their relative distribution and projection pattern. Here we employ in situ hybridization to definitively identify transmitter types combined with retrograde labeling of projections to the inferior colliculus (IC) to address these questions. Excitatory LSO neurons were more numerous (76%) than inhibitory ones. A smaller proportion of inhibitory neurons were IC-projecting (45% vs. 64% for excitatory) suggesting that inhibitory LSO neurons may have more projections to other regions such the lateral lemniscus or more distributed IC projections. Inhibitory LSO neurons almost exclusively projected ipsilaterally making up a sizeable proportion (41%) of the transmitter type-labeled ipsilateral IC projection from LSO and exhibited a moderate low frequency bias (10% difference H-L). Two thirds of excitatory neurons projected contralaterally and had a slight high frequency bias (4%). One third of excitatory LSO neurons projected ipsilaterally to the IC and these cells were strongly biased toward the low frequency limb of the LSO (37%). This projection appears to be species specific in animals with good low frequency hearing suggesting that it may be a specialization for such ability.
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Affiliation(s)
- Jeffrey G. Mellott
- Department of Anatomy and Neurobiology, Hearing Research Group, Northeast Ohio Medical University, Hearing Research Group, Rootstown, OH, United States,Brain Health Research Institute, Kent State University, Kent, OH, United States
| | - Matasha Dhar
- Department of Anatomy and Neurobiology, Hearing Research Group, Northeast Ohio Medical University, Hearing Research Group, Rootstown, OH, United States
| | - Amir Mafi
- Department of Anatomy and Neurobiology, Hearing Research Group, Northeast Ohio Medical University, Hearing Research Group, Rootstown, OH, United States
| | - Nick Tokar
- Department of Anatomy and Neurobiology, Hearing Research Group, Northeast Ohio Medical University, Hearing Research Group, Rootstown, OH, United States
| | - Bradley D. Winters
- Department of Anatomy and Neurobiology, Hearing Research Group, Northeast Ohio Medical University, Hearing Research Group, Rootstown, OH, United States,Brain Health Research Institute, Kent State University, Kent, OH, United States
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19
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Jing Z, Pecka M, Grothe B. Ketamine-xylazine anesthesia depth affects auditory neuronal responses in the lateral superior olive complex of the gerbil. J Neurophysiol 2021; 126:1660-1669. [PMID: 34644166 DOI: 10.1152/jn.00217.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Studies of in vivo neuronal responses to auditory inputs in the superior olive complex (SOC) are usually done under anesthesia. However, little attention has been paid to the effect of anesthesia itself on response properties. Here, we assessed the effect of anesthesia depth under ketamine-xylazine anesthetics on auditory evoked response properties of lateral SOC neurons. Anesthesia depth was tracked by monitoring EEG spectral peak frequencies. An increase in anesthesia depth led to a decrease of spontaneous discharge activities and an elevated response threshold. The temporal responses to suprathreshold tones were also affected, with adapted responses reduced but peak responses unaffected. Deepening the anesthesia depth also increased first spike latency. However, spike jitter was not affected. Auditory brainstem responses to clicks confirmed that ketamine-xylazine anesthesia depth affects auditory neuronal activities and the effect on spike rate and spike timing persists through the auditory pathway. We concluded from those observations that ketamine-xylazine affects lateral SOC response properties depending on the anesthesia depth.NEW & NOTEWORTHY We studied how the depth of ketamine-xylazine anesthesia altered response properties of lateral superior olive complex neurons, and auditory brainstem evoked responses. Our results provide direct evidence that anesthesia depth affects auditory neuronal responses and reinforce the notion that both the anesthetics and the anesthesia depth should be considered when interpreting/comparing in vivo neuronal recordings.
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Affiliation(s)
- Zhizi Jing
- Division of Neurobiology, Department of Biology II, Ludwig Maximilian University of Munich, Martinsried, Germany
| | - Michael Pecka
- Division of Neurobiology, Department of Biology II, Ludwig Maximilian University of Munich, Martinsried, Germany
| | - Benedikt Grothe
- Division of Neurobiology, Department of Biology II, Ludwig Maximilian University of Munich, Martinsried, Germany
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20
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Bondy BJ, Haimes DB, Golding NL. Physiological Diversity Influences Detection of Stimulus Envelope and Fine Structure in Neurons of the Medial Superior Olive. J Neurosci 2021; 41:6234-6245. [PMID: 34083255 PMCID: PMC8287997 DOI: 10.1523/jneurosci.2354-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 01/10/2023] Open
Abstract
The neurons of the medial superior olive (MSO) of mammals extract azimuthal information from the delays between sounds reaching the two ears [interaural time differences (ITDs)]. Traditionally, all models of sound localization have assumed that MSO neurons represent a single population of cells with specialized and homogeneous intrinsic and synaptic properties that enable the detection of synaptic coincidence on a timescale of tens to hundreds of microseconds. Here, using patch-clamp recordings from large populations of anatomically labeled neurons in brainstem slices from male and female Mongolian gerbils (Meriones unguiculatus), we show that MSO neurons are far more physiologically diverse than previously appreciated, with properties that depend regionally on cell position along the topographic map of frequency. Despite exhibiting a similar morphology, neurons in the MSO exhibit subthreshold oscillations of differing magnitudes that drive action potentials at rates between 100 and 800 Hz. These oscillations are driven primarily by voltage-gated sodium channels and are distinct from resonant properties derived from other active membrane properties. We show that graded differences in these and other physiological properties across the MSO neuron population enable the MSO to duplex the encoding of ITD information in both fast, submillisecond time-varying signals as well as in slower envelopes.SIGNIFICANCE STATEMENT Neurons in the medial superior olive (MSO) encode sound localization cues by detecting microsecond differences in the arrival times of inputs from the left and right ears, and it has been assumed that this computation is made possible by highly stereotyped structural and physiological specializations. Here we report using a large (>400) sample size in which MSO neurons show a strikingly large continuum of functional properties despite exhibiting similar morphologies. We demonstrate that subthreshold oscillations mediated by voltage-gated Na+ channels play a key role in conferring graded differences in firing properties. This functional diversity likely confers capabilities of processing both fast, submillisecond-scale synaptic activity (acoustic "fine structure"), and slow-rising envelope information that is found in amplitude-modulated sounds and speech patterns.
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Affiliation(s)
- Brian J Bondy
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
| | - David B Haimes
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
| | - Nace L Golding
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
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21
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Ashida G, Tollin DJ, Kretzberg J. Robustness of neuronal tuning to binaural sound localization cues against age-related loss of inhibitory synaptic inputs. PLoS Comput Biol 2021; 17:e1009130. [PMID: 34242210 PMCID: PMC8270189 DOI: 10.1371/journal.pcbi.1009130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 05/30/2021] [Indexed: 11/19/2022] Open
Abstract
Sound localization relies on minute differences in the timing and intensity of sound arriving at both ears. Neurons of the lateral superior olive (LSO) in the brainstem process these interaural disparities by precisely detecting excitatory and inhibitory synaptic inputs. Aging generally induces selective loss of inhibitory synaptic transmission along the entire auditory pathways, including the reduction of inhibitory afferents to LSO. Electrophysiological recordings in animals, however, reported only minor functional changes in aged LSO. The perplexing discrepancy between anatomical and physiological observations suggests a role for activity-dependent plasticity that would help neurons retain their binaural tuning function despite loss of inhibitory inputs. To explore this hypothesis, we use a computational model of LSO to investigate mechanisms underlying the observed functional robustness against age-related loss of inhibitory inputs. The LSO model is an integrate-and-fire type enhanced with a small amount of low-voltage activated potassium conductance and driven with (in)homogeneous Poissonian inputs. Without synaptic input loss, model spike rates varied smoothly with interaural time and level differences, replicating empirical tuning properties of LSO. By reducing the number of inhibitory afferents to mimic age-related loss of inhibition, overall spike rates increased, which negatively impacted binaural tuning performance, measured as modulation depth and neuronal discriminability. To simulate a recovery process compensating for the loss of inhibitory fibers, the strength of remaining inhibitory inputs was increased. By this modification, effects of inhibition loss on binaural tuning were considerably weakened, leading to an improvement of functional performance. These neuron-level observations were further confirmed by population modeling, in which binaural tuning properties of multiple LSO neurons were varied according to empirical measurements. These results demonstrate the plausibility that homeostatic plasticity could effectively counteract known age-dependent loss of inhibitory fibers in LSO and suggest that behavioral degradation of sound localization might originate from changes occurring more centrally.
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Affiliation(s)
- Go Ashida
- Cluster of Excellence "Hearing4all", Department of Neuroscience, University of Oldenburg, Oldenburg, Germany
- * E-mail:
| | - Daniel J. Tollin
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Jutta Kretzberg
- Cluster of Excellence "Hearing4all", Department of Neuroscience, University of Oldenburg, Oldenburg, Germany
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22
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Franken TP, Bondy BJ, Haimes DB, Goldwyn JH, Golding NL, Smith PH, Joris PX. Glycinergic axonal inhibition subserves acute spatial sensitivity to sudden increases in sound intensity. eLife 2021; 10:62183. [PMID: 34121662 PMCID: PMC8238506 DOI: 10.7554/elife.62183] [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: 08/17/2020] [Accepted: 06/12/2021] [Indexed: 11/20/2022] Open
Abstract
Locomotion generates adventitious sounds which enable detection and localization of predators and prey. Such sounds contain brisk changes or transients in amplitude. We investigated the hypothesis that ill-understood temporal specializations in binaural circuits subserve lateralization of such sound transients, based on different time of arrival at the ears (interaural time differences, ITDs). We find that Lateral Superior Olive (LSO) neurons show exquisite ITD-sensitivity, reflecting extreme precision and reliability of excitatory and inhibitory postsynaptic potentials, in contrast to Medial Superior Olive neurons, traditionally viewed as the ultimate ITD-detectors. In vivo, inhibition blocks LSO excitation over an extremely short window, which, in vitro, required synaptically evoked inhibition. Light and electron microscopy revealed inhibitory synapses on the axon initial segment as the structural basis of this observation. These results reveal a neural vetoing mechanism with extreme temporal and spatial precision and establish the LSO as the primary nucleus for binaural processing of sound transients.
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Affiliation(s)
- Tom P Franken
- Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Systems Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Brian J Bondy
- Department of Neuroscience, University of Texas at Austin, Austin, United States
| | - David B Haimes
- Department of Neuroscience, University of Texas at Austin, Austin, United States
| | - Joshua H Goldwyn
- Department of Mathematics and Statistics, Swarthmore College, Swarthmore, United States
| | - Nace L Golding
- Department of Neuroscience, University of Texas at Austin, Austin, United States
| | - Philip H Smith
- Department of Neuroscience, University of Wisconsin-Madison, Madison, United States
| | - Philip X Joris
- Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
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23
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Wu C, Peng Y, Liu Y, Wei J, Xiao Z. Synaptic excitation underlies processing of paired stimulation in the mouse inferior colliculus. Eur J Neurosci 2021; 53:2511-2531. [PMID: 33595869 DOI: 10.1111/ejn.15149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 02/09/2021] [Accepted: 02/11/2021] [Indexed: 11/28/2022]
Abstract
The inferior colliculus (IC) receives inputs from the ascending auditory pathway and helps localize the sound source by shaping neurons' responses. However, the contributions of excitatory or inhibitory synaptic inputs evoked by paired binaural stimuli with different inter-stimulus intervals to auditory responses of IC neurons remain unclear. Here, we firstly investigated the IC neuronal response to the paired binaural stimuli with different inter-stimulus intervals using in vivo loose-patch recordings in anesthetized C57BL/6 mice. It was found that the total acoustic evoked spikes remained unchanged under microsecond interval conditions, but persistent suppression would be observed when the time intervals were extended. We further studied the paired binaural stimuli evoked excitatory/inhibitory inputs using in vivo whole-cell voltage-clamp techniques and blockage of the auditory nerve. The amplitudes of the contralateral excitatory inputs could be suppressed, unaffected or facilitated as the interaural delay varied. In contrast, contralateral inhibitory inputs and ipsilateral synaptic inputs remained almost unchanged. Most IC neurons exhibited the suppression of contralateral excitatory inputs over the interval range of dozens of milliseconds. The facilitative effect was generated by the summation of contralateral and ipsilateral excitation. Suppression and facilitation were completely abolished when ipsilateral auditory nerve was blocked pharmacologically, indicating that these effects were exerted by ipsilateral stimulation. These results suggested that the IC would inherit the binaural inputs integrated at the brainstem as well as within the IC and synaptic excitations, modulated by ipsilateral stimulation, underlie the binaural acoustic response.
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Affiliation(s)
- Chaochen Wu
- Department of Physiology, School of Basic Medical Sciences, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Yunyi Peng
- Department of Physiology, School of Basic Medical Sciences, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Yun Liu
- Department of Physiology, School of Basic Medical Sciences, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Jinxing Wei
- Department of Physiology, School of Basic Medical Sciences, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Zhongju Xiao
- Department of Physiology, School of Basic Medical Sciences, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
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Curry RJ, Lu Y. Intrinsic properties of avian interaural level difference sound localizing neurons. Brain Res 2021; 1752:147258. [PMID: 33422536 DOI: 10.1016/j.brainres.2020.147258] [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: 10/15/2020] [Revised: 12/02/2020] [Accepted: 12/19/2020] [Indexed: 11/15/2022]
Abstract
Intrinsic properties of neurons are one major determinant for how neurons respond to their synaptic inputs and shape their outputs in neural circuits. Here, we studied the intrinsic properties of neurons in the chicken posterior portion of the dorsal nucleus of the lateral lemniscus (LLDp), the first interaural level difference (ILD) encoder of the avian auditory pathway. Using whole-cell recordings in brain slices, we revealed that the LLDp is composed of a heterogeneous neuron population based on their firing patterns. LLDp neurons were broadly classified as either phasic or tonic firing neurons, with further classification applied to tonic firing neurons, such as regular (most dominant, n = 82 out of 125 cells, 65.6%), pauser, or adaptive firing. Neurons with different firing patterns were distributed about evenly across the dorsoventral as well as mediolateral axis of LLDp. Phasic firing neurons were of faster membrane time constant, and lower excitability than tonic firing neurons. The action potentials (APs) elicited at the current thresholds displayed significant differences in first spike latency, AP peak amplitude, half-width, and maximal rising and falling rates. Interestingly, for APs elicited at suprathreshold currents (400 pA above thresholds), some of the differences diminished while a few others emerged. Remarkably, most parameters of the APs at thresholds were significantly different from those of APs at suprathresholds. Combined with our previous study (Curry and Lu, 2016), the results lend support to the two-cell type model for ILD coding in the avian system.
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Affiliation(s)
- Rebecca J Curry
- Department of Anatomy and Neurobiology, Hearing Research Group, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA
| | - Yong Lu
- Department of Anatomy and Neurobiology, Hearing Research Group, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA.
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25
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Haqqee Z, Valdizón-Rodríguez R, Faure PA. High frequency sensitivity to interaural onset time differences in the bat inferior colliculus. Hear Res 2020; 400:108133. [PMID: 33340969 DOI: 10.1016/j.heares.2020.108133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 11/20/2020] [Accepted: 11/25/2020] [Indexed: 02/02/2023]
Abstract
Many neurons in the auditory midbrain are tuned to binaural cues. Two prominent binaural cues are the interaural level difference (ILD) and the interaural time difference (ITD). The ITD cue can further be subdivided into the ongoing envelope ITD cues and transient onset ITD cues. More is known about the sensitivity of single neurons to ongoing envelope ITDs compared to transient onset ITDs in the mammalian auditory system, particularly in bats. The current study examines the response properties of single neurons in the inferior colliculus (IC) of the big brown bat, Eptesicus fuscus, to onset ITDs in response to high frequency pure tones. Measures of neurons' dynamic ITD response revealed an average change of 36% of its maximum response within the behaviorally relevant range of ITDs (±50 µs). Across all IC neurons, we measured an average time-intensity trading ratio of 30 µs/dB in the sensitivity of the ITD response function to changing ILDs. Minimum and maximum ITD responses were clustered within a narrow range of ITDs. The average peak in the ITD response function was at 268 µs, a finding that is consistent with other non-echolocating mammals. Some ITD-sensitive neurons also showed weak facilitation of maximum response during binaural stimulation, compared to monaural stimulation. These results suggest that echolocating bats possess the potential to use onset ITD cues to assist in the azimuthal sound localization of ultrasonic frequencies.
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Affiliation(s)
- Zeeshan Haqqee
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | | | - Paul A Faure
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, L8S 4K1, Canada.
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26
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Haragopal H, Dorkoski R, Pollard AR, Whaley GA, Wohl TR, Stroud NC, Day ML. Specific loss of neural sensitivity to interaural time difference of unmodulated noise stimuli following noise-induced hearing loss. J Neurophysiol 2020; 124:1165-1182. [PMID: 32845200 DOI: 10.1152/jn.00349.2020] [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] [Indexed: 11/22/2022] Open
Abstract
Sensorineural hearing loss (SNHL) causes an overall deficit in binaural hearing, including the abilities to localize sound sources, discriminate interaural time and level differences (ITDs and ILDs, respectively), and utilize binaural cues to aid signal detection and comprehension in noisy environments. Few studies have examined the effect of SNHL on binaural coding in the central auditory system, and those that have focused on age-related hearing loss. We induced hearing loss in male and female Dutch-belted rabbits via noise overexposure and compared unanesthetized single-unit responses of their inferior colliculi [hearing loss (HL) neurons] with those of unexposed rabbits. Sound-level thresholds of HL neurons to diotic noise were elevated by 75 dB, on average. Sensitivity of firing rates of HL neurons to the azimuth of a broadband noise stimulus was reduced, on average, but was confounded by differences in sound level with respect to detection threshold between groups. We independently manipulated ITD and ILD in virtual acoustic space and found directional sensitivity in binaurally sensitive HL neurons was entirely due to ILD sensitivity and no different than that for unexposed rabbits. However, ITD sensitivity was completely absent in binaurally sensitive HL neurons for noise stimuli both in virtual acoustic space and with ITDs extending to ±3 ms. HL neurons also had weaker spike-timing precision and slightly increased spontaneous rates. Overall, ILD sensitivity was uncompromised, whereas ITD sensitivity was completely lost, implying a specific inability to use information in the timing or correlation of acoustic noise waveforms between the two ears following severe SNHL.NEW & NOTEWORTHY Sensorineural hearing loss compromises perceptual abilities that arise from hearing with two ears, yet its effects on binaural aspects of neural responses are largely unknown. We found that, following severe hearing loss because of acoustic trauma, auditory midbrain neurons specifically lost the ability to encode time differences between the arrival of a broadband noise stimulus to the two ears, whereas the encoding of sound level differences between the two ears remained uncompromised.
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Affiliation(s)
| | - Ryan Dorkoski
- Department of Biological Sciences, Ohio University, Athens, Ohio
| | - Austin R Pollard
- Department of Biological Sciences, Ohio University, Athens, Ohio
| | - Gareth A Whaley
- Department of Biological Sciences, Ohio University, Athens, Ohio
| | - Timothy R Wohl
- Department of Biological Sciences, Ohio University, Athens, Ohio
| | - Noelle C Stroud
- Department of Biological Sciences, Ohio University, Athens, Ohio
| | - Mitchell L Day
- Department of Biological Sciences, Ohio University, Athens, Ohio.,Quantitative Biology Institute, Ohio University, Athens, Ohio
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27
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Choudhury N, Linley D, Richardson A, Anderson M, Robinson SW, Marra V, Ciampani V, Walter SM, Kopp‐Scheinpflug C, Steinert JR, Forsythe ID. Kv3.1 and Kv3.3 subunits differentially contribute to Kv3 channels and action potential repolarization in principal neurons of the auditory brainstem. J Physiol 2020; 598:2199-2222. [DOI: 10.1113/jp279668] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- Nasreen Choudhury
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Deborah Linley
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Amy Richardson
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Michelle Anderson
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Susan W. Robinson
- Neurotoxicity at the Synaptic Interface MRC Toxicology Unit University of Leicester, UK
| | - Vincenzo Marra
- Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Victoria Ciampani
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Sophie M. Walter
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Conny Kopp‐Scheinpflug
- Division of Neurobiology Department Biology II Ludwig‐Maximilians‐University Munich Großhaderner Strasse 2 Planegg‐Martinsried D‐82152 Germany
| | - Joern R. Steinert
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Ian D. Forsythe
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
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28
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Strelcyk O, Zahorik P, Shehorn J, Patro C, Derleth RP. Sensitivity to Interaural Phase in Older Hearing-Impaired Listeners Correlates With Nonauditory Trail Making Scores and With a Spatial Auditory Task of Unrelated Peripheral Origin. Trends Hear 2020; 23:2331216519864499. [PMID: 31455167 PMCID: PMC6755865 DOI: 10.1177/2331216519864499] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Interaural phase difference (IPD) discrimination upper frequency limits and just-noticeable differences (JNDs), interaural level difference (ILD) JNDs, and diotic intensity JNDs were measured for 20 older hearing-impaired listeners with matched moderate sloping to severe sensorineural hearing losses. The JNDs were measured using tone stimuli at 500 Hz. In addition to these auditory tests, the participants completed a cognitive test (Trail Making Test). Significant performance improvements in IPD discrimination were observed across test sessions. Strong correlations were found between IPD and ILD discrimination performance. Very strong correlations were observed between IPD discrimination and Trail Making performance as well as strong correlations between ILD discrimination and Trail Making performance. These relationships indicate that interindividual variability in IPD discrimination performance did not exclusively reflect deficits specific to any auditory processing, including early auditory processing of temporal information. The observed relationships between spatial audition and cognition may instead be attributable to a modality-general spatial processing deficit and/or individual differences in global processing speed.
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Affiliation(s)
- Olaf Strelcyk
- 1 Sonova U.S. Corporate Services, Warrenville, IL, USA
| | - Pavel Zahorik
- 2 Department of Otolaryngology and Communicative Disorders, University of Louisville, Louisville, KY, USA.,3 Department of Psychological and Brain Sciences, University of Louisville, Louisville, KY, USA.,4 Heuser Hearing Research Center, Louisville, KY, USA
| | - James Shehorn
- 4 Heuser Hearing Research Center, Louisville, KY, USA
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29
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Zhou M, Yuan J, Yan Z, Dai J, Wang X, Xu T, Xu Z, Wang N, Liu J. Intrinsic and Miniature Postsynaptic Current Changes in Rat Principal Neurons of the Lateral Superior Olive after Unilateral Auditory Deprivation at an Early Age. Neuroscience 2019; 428:2-12. [PMID: 31866557 DOI: 10.1016/j.neuroscience.2019.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 11/30/2019] [Accepted: 12/02/2019] [Indexed: 01/13/2023]
Abstract
Unilateral auditory deprivation results in lateralization changes in the central auditory system, interfering with the integration of binaural information and thereby leading to a decrease in binaural auditory functions such as sound localization. Principal neurons of the lateral superior olive (LSO) are responsible for computing the interaural intensity differences that are critical for sound localization in the horizontal plane. To investigate changes caused by unilateral auditory deprivation, electrophysiological activity was recorded from LSO principal neurons in control rats and rats with unilateral cochlear ablation. At one week after unilateral cochlear ablation, the excitability of LSO principal neurons on the side ipsilateral to the ablation (the ablated side) was greater than that on the side contralateral to the ablation (the intact side); however, the input resistance increased on both sides. Furthermore, by analysing the miniature inhibitory postsynaptic currents and miniature excitatory postsynaptic currents, we found that unilateral auditory deprivation weakened the inhibitory driving force on the intact side, whereas it strengthened the excitatory driving force on the ablated side. In summary, asymmetric changes in the electrophysiological activity of LSO principal neurons were found on both sides at postnatal day 19, one week after unilateral cochlear ablation.
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Affiliation(s)
- Mo Zhou
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Jingjing Yuan
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Zhanfeng Yan
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Jinsheng Dai
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Xing Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Tao Xu
- Department of Neurobiology, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Laboratory of Brain Disorders (Ministry of Science and Technology), Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
| | - Zhiqing Xu
- Department of Neurobiology, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Laboratory of Brain Disorders (Ministry of Science and Technology), Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
| | - Ningyu Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
| | - Jinfeng Liu
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
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30
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Kuenzel T. Modulatory influences on time-coding neurons in the ventral cochlear nucleus. Hear Res 2019; 384:107824. [DOI: 10.1016/j.heares.2019.107824] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 09/10/2019] [Accepted: 10/14/2019] [Indexed: 02/07/2023]
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31
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Abstract
The neural coding metaphor is so ubiquitous that we tend to forget its metaphorical nature. What do we mean when we assert that neurons encode and decode? What kind of causal and representational model of the brain does the metaphor entail? What lies beneath the neural coding metaphor, I argue, is a bureaucratic model of the brain.
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32
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Yin TC, Smith PH, Joris PX. Neural Mechanisms of Binaural Processing in the Auditory Brainstem. Compr Physiol 2019; 9:1503-1575. [DOI: 10.1002/cphy.c180036] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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33
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Brown AD, Anbuhl KL, Gilmer JI, Tollin DJ. Between-ear sound frequency disparity modulates a brain stem biomarker of binaural hearing. J Neurophysiol 2019; 122:1110-1122. [PMID: 31314646 PMCID: PMC6766741 DOI: 10.1152/jn.00057.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 11/22/2022] Open
Abstract
The auditory brain stem response (ABR) is an evoked potential that indexes a cascade of neural events elicited by sound. In the present study we evaluated the influence of sound frequency on a derived component of the ABR known as the binaural interaction component (BIC). Specifically, we evaluated the effect of acoustic interaural (between-ear) frequency mismatch on BIC amplitude. Goals were to 1) increase basic understanding of sound features that influence this long-studied auditory potential and 2) gain insight about the persistence of the BIC with interaural electrode mismatch in human users of bilateral cochlear implants, presently a limitation on the prospective utility of the BIC in audiological settings. Data were collected in an animal model that is audiometrically similar to humans, the chinchilla (Chinchilla lanigera; 6 females). Frequency disparities and amplitudes of acoustic stimuli were varied over broad ranges, and associated variation of BIC amplitude was quantified. Subsequently, responses were simulated with the use of established models of the brain stem pathway thought to underlie the BIC. Collectively, the data demonstrate that at high sound intensities (≥85 dB SPL), the acoustically elicited BIC persisted with interaurally disparate stimulation (click frequencies ≥1.5 octaves apart). However, sharper tuning emerged at moderate sound intensities (65 dB SPL), with the largest BIC occurring for stimulus frequencies within ~0.8 octaves, equivalent to ±1 mm in cochlear place. Such responses were consistent with simulated responses of the presumed brain stem generator of the BIC, the lateral superior olive. The data suggest that leveraging focused electrical stimulation strategies could improve BIC-based bilateral cochlear implant fitting outcomes.NEW & NOTEWORTHY Traditional hearing tests evaluate each ear independently. Diagnosis and treatment of binaural hearing dysfunction remains a basic challenge for hearing clinicians. We demonstrate in an animal model that the prospective utility of a noninvasive electrophysiological signature of binaural function, the binaural interaction component (BIC), depends strongly on the intensity of auditory stimulation. Data suggest that more informative BIC measurements could be obtained with clinical protocols leveraging stimuli restricted in effective bandwidth.
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Affiliation(s)
- Andrew D Brown
- Department of Speech and Hearing Sciences, University of Washington, Seattle, Washington
| | - Kelsey L Anbuhl
- Center for Neural Science, New York University, New York, New York
| | - Jesse I Gilmer
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado
- Neuroscience Training Program, University of Colorado School of Medicine, Aurora, Colorado
| | - Daniel J Tollin
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado
- Neuroscience Training Program, University of Colorado School of Medicine, Aurora, Colorado
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado
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34
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Brill SE, Janz K, Singh A, Friauf E. Considerable differences between auditory medulla, auditory midbrain, and hippocampal synapses during sustained high-frequency stimulation: Exceptional vesicle replenishment restricted to sound localization circuit. Hear Res 2019; 381:107771. [PMID: 31394425 DOI: 10.1016/j.heares.2019.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 07/11/2019] [Accepted: 07/14/2019] [Indexed: 11/25/2022]
Abstract
Reliable synaptic transmission is essential for interneuronal communication. Synaptic inputs to auditory brainstem neurons, particularly those involved in sound localization, are characterized by resilience during sustained activity and temporal precision in the sub-millisecond range. Both features are obtained by synchronous release of a high number of synaptic vesicles following a single action potential. Here, we compare transmission behavior of three heterogeneous types of inputs in the auditory midbrain and medulla. The first terminate in the central inferior colliculus (ICc) and are glutamatergic (activated from the lateral lemniscus, LL). The medullary inputs terminate in the lateral superior olive (LSO) and are glutamatergic (from the cochlear nuclear complex, CN) or glycinergic (from the medial nucleus of the trapezoid body, MNTB). LSO neurons are the first to integrate binaural information and compute interaural level differences, whereas ICc neurons receive information from almost all auditory brainstem nuclei and construct an initial auditory image used for reflexive behavior. We hypothesized that CN-LSO and MNTB-LSO inputs are more resilient to synaptic fatigue during sustained stimulation than LL-ICc inputs. To test the hypothesis, we performed whole-cell patch-clamp recordings in acute brainstem slices of juvenile mice. We investigated the synaptic performance during prolonged periods of high-frequency stimulation (60 s, up to 200 Hz) and assessed several features, e.g. depression, recovery, latency, temporal precision, quantal size and content, readily releasable pool size, release probability, and replenishment rate. Overall, LL-ICc inputs performed less robustly and temporally precisely than CN-LSO and MNTB-LSO inputs. When stimulated at ≥50 Hz, the former depressed completely within a few seconds. In contrast, CN-LSO and MNTB-LSO inputs transmitted faithfully up to 200 Hz, indicative of very efficient replenishment mechanisms. LSO inputs also displayed considerably lower latency jitter than LL-ICc inputs. The latter behaved similarly to two types of input in the hippocampus for which we performed a meta-analysis. Mechanistically, the high-fidelity behavior of LSO inputs, particularly MNTB-LSO synapses, is based on exceptional release properties not present at auditory midbrain or hippocampal inputs. We conclude that robustness and temporal precision are hallmarks of auditory synapses in the medullary brainstem. These key features are less eminent at higher stations, such as the ICc, and they are also absent outside the central auditory system, namely the hippocampal formation.
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Affiliation(s)
- Sina E Brill
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Katrin Janz
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany
| | - Abhyudai Singh
- Electrical & Computer Engineering, University of Delaware, Newark, DE, USA
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, D-67663, Kaiserslautern, Germany.
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35
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Joris PX, van der Heijden M. Early Binaural Hearing: The Comparison of Temporal Differences at the Two Ears. Annu Rev Neurosci 2019; 42:433-457. [DOI: 10.1146/annurev-neuro-080317-061925] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many mammals, including humans, are exquisitely sensitive to tiny time differences between sounds at the two ears. These interaural time differences are an important source of information for sound detection, for sound localization in space, and for environmental awareness. Two brainstem circuits are involved in the initial temporal comparisons between the ears, centered on the medial and lateral superior olive. Cells in these nuclei, as well as their afferents, display a large number of striking physiological and anatomical specializations to enable submillisecond sensitivity. As such, they provide an important model system to study temporal processing in the central nervous system. We review the progress that has been made in characterizing these primary binaural circuits as well as the variety of mechanisms that have been proposed to underlie their function.
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Affiliation(s)
- Philip X. Joris
- Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
| | - Marcel van der Heijden
- Department of Neuroscience, Erasmus University Medical Center, 3000 CA Rotterdam, Netherlands
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36
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Brown DH, Hyson RL. Intrinsic physiological properties underlie auditory response diversity in the avian cochlear nucleus. J Neurophysiol 2019; 121:908-927. [PMID: 30649984 DOI: 10.1152/jn.00459.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sensory systems exploit parallel processing of stimulus features to enable rapid, simultaneous extraction of information. Mechanisms that facilitate this differential extraction of stimulus features can be intrinsic or synaptic in origin. A subdivision of the avian cochlear nucleus, nucleus angularis (NA), extracts sound intensity information from the auditory nerve and contains neurons that exhibit diverse responses to sound and current injection. NA neurons project to multiple regions ascending the auditory brain stem including the superior olivary nucleus, lateral lemniscus, and avian inferior colliculus, with functional implications for inhibitory gain control and sound localization. Here we investigated whether the diversity of auditory response patterns in NA can be accounted for by variation in intrinsic physiological features. Modeled sound-evoked auditory nerve input was applied to NA neurons with dynamic clamp during in vitro whole cell recording at room temperature. Temporal responses to auditory nerve input depended on variation in intrinsic properties, and the low-threshold K+ current was implicated as a major contributor to temporal response diversity and neuronal input-output functions. An auditory nerve model of acoustic amplitude modulation produced synchrony coding of modulation frequency that depended on the intrinsic physiology of the individual neuron. In Primary-Like neurons, varying low-threshold K+ conductance with dynamic clamp altered temporal modulation tuning bidirectionally. Taken together, these data suggest that intrinsic physiological properties play a key role in shaping auditory response diversity to both simple and more naturalistic auditory stimuli in the avian cochlear nucleus. NEW & NOTEWORTHY This article addresses the question of how the nervous system extracts different information in sounds. Neurons in the cochlear nucleus show diverse responses to acoustic stimuli that may allow for parallel processing of acoustic features. The present studies suggest that diversity in intrinsic physiological features of individual neurons, including levels of a low voltage-activated K+ current, play a major role in regulating the diversity of auditory responses.
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Affiliation(s)
- David H Brown
- Program in Neuroscience, Department of Psychology, Florida State University , Tallahassee, Florida
| | - Richard L Hyson
- Program in Neuroscience, Department of Psychology, Florida State University , Tallahassee, Florida
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37
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Joris PX, Trussell LO. The Calyx of Held: A Hypothesis on the Need for Reliable Timing in an Intensity-Difference Encoder. Neuron 2018; 100:534-549. [PMID: 30408442 PMCID: PMC6263157 DOI: 10.1016/j.neuron.2018.10.026] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 08/16/2018] [Accepted: 10/15/2018] [Indexed: 12/18/2022]
Abstract
The calyx of Held is the preeminent model for the study of synaptic function in the mammalian CNS. Despite much work on the synapse and associated circuit, its role in hearing remains enigmatic. We propose that the calyx is one of the key adaptations that enables an animal to lateralize transient sounds. The calyx is part of a binaural circuit that is biased toward high sound frequencies and is sensitive to intensity differences between the ears. This circuit also shows marked sensitivity to interaural time differences, but only for brief sound transients ("clicks"). In a natural environment, such transients are rare except as adventitious sounds generated by other animals moving at close range. We argue that the calyx, and associated temporal specializations, evolved to enable spatial localization of sound transients, through a neural code congruent with the circuit's sensitivity to interaural intensity differences, thereby conferring a key benefit to survival.
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Affiliation(s)
- Philip X Joris
- Laboratory of Auditory Neurophysiology, Department of Neurosciences, University of Leuven, Leuven B-3000, Belgium.
| | - Laurence O Trussell
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
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38
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Benichoux V, Tollin DJ. These are not the neurons you are looking for. eLife 2018; 7:39244. [PMID: 30052196 PMCID: PMC6063726 DOI: 10.7554/elife.39244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 07/18/2018] [Indexed: 11/13/2022] Open
Abstract
Studies that looked into how the auditory brainstem processes the difference in the intensity of a sound as it reaches each ear may have wrongly assumed which neurons were being recorded.
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Affiliation(s)
- Victor Benichoux
- Unit of Genetics and Physiology of Hearing, Department of Neuroscience, Institut Pasteur, Paris, France
| | - Daniel J Tollin
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, United States
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