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Stoll A, Maier A, Krauss P, Gerum R, Schilling A. Coincidence detection and integration behavior in spiking neural networks. Cogn Neurodyn 2024; 18:1753-1765. [PMID: 39104689 PMCID: PMC11297875 DOI: 10.1007/s11571-023-10038-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 09/11/2023] [Accepted: 11/09/2023] [Indexed: 08/07/2024] Open
Abstract
Recently, the interest in spiking neural networks (SNNs) remarkably increased, as up to now some key advances of biological neural networks are still out of reach. Thus, the energy efficiency and the ability to dynamically react and adapt to input stimuli as observed in biological neurons is still difficult to achieve. One neuron model commonly used in SNNs is the leaky-integrate-and-fire (LIF) neuron. LIF neurons already show interesting dynamics and can be run in two operation modes: coincidence detectors for low and integrators for high membrane decay times, respectively. However, the emergence of these modes in SNNs and the consequence on network performance and information processing ability is still elusive. In this study, we examine the effect of different decay times in SNNs trained with a surrogate-gradient-based approach. We propose two measures that allow to determine the operation mode of LIF neurons: the number of contributing input spikes and the effective integration interval. We show that coincidence detection is characterized by a low number of input spikes as well as short integration intervals, whereas integration behavior is related to many input spikes over long integration intervals. We find the two measures to linearly correlate via a correlation factor that depends on the decay time. Thus, the correlation factor as function of the decay time shows a powerlaw behavior, which could be an intrinsic property of LIF networks. We argue that our work could be a starting point to further explore the operation modes in SNNs to boost efficiency and biological plausibility. Supplementary Information The online version of this article (10.1007/s11571-023-10038-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andreas Stoll
- Pattern Recognition Lab, University Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Maier
- Pattern Recognition Lab, University Erlangen-Nürnberg, Erlangen, Germany
| | - Patrick Krauss
- Pattern Recognition Lab, University Erlangen-Nürnberg, Erlangen, Germany
- Neuroscience Lab, University Hospital Erlangen, Erlangen, Germany
| | - Richard Gerum
- Department of Physics and Astronomy, York University, Toronto, Canada
| | - Achim Schilling
- Pattern Recognition Lab, University Erlangen-Nürnberg, Erlangen, Germany
- Neuroscience Lab, University Hospital Erlangen, Erlangen, Germany
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2
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Sierksma MC, Borst JGG. Developmental fine-tuning of medial superior olive neurons mitigates their predisposition to contralateral sound sources. PLoS Biol 2024; 22:e3002586. [PMID: 38683852 PMCID: PMC11081505 DOI: 10.1371/journal.pbio.3002586] [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: 03/02/2023] [Revised: 05/09/2024] [Accepted: 03/12/2024] [Indexed: 05/02/2024] Open
Abstract
Having two ears enables us to localize sound sources by exploiting interaural time differences (ITDs) in sound arrival. Principal neurons of the medial superior olive (MSO) are sensitive to ITD, and each MSO neuron responds optimally to a best ITD (bITD). In many cells, especially those tuned to low sound frequencies, these bITDs correspond to ITDs for which the contralateral ear leads, and are often larger than the ecologically relevant range, defined by the ratio of the interaural distance and the speed of sound. Using in vivo recordings in gerbils, we found that shortly after hearing onset the bITDs were even more contralaterally leading than found in adult gerbils, and travel latencies for contralateral sound-evoked activity clearly exceeded those for ipsilateral sounds. During the following weeks, both these latencies and their interaural difference decreased. A computational model indicated that spike timing-dependent plasticity can underlie this fine-tuning. Our results suggest that MSO neurons start out with a strong predisposition toward contralateral sounds due to their longer neural travel latencies, but that, especially in high-frequency neurons, this predisposition is subsequently mitigated by differential developmental fine-tuning of the travel latencies.
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Affiliation(s)
- Martijn C. Sierksma
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - J. Gerard G. Borst
- Department of Neuroscience, Erasmus MC, Erasmus University Medical Center, Rotterdam, the Netherlands
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3
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Wang R, Gu H, Zhang X. Dynamics of interaction between IH and IKLT currents to mediate double resonances of medial superior olive neurons related to sound localization. Cogn Neurodyn 2024; 18:715-740. [PMID: 38699604 PMCID: PMC11061090 DOI: 10.1007/s11571-023-10024-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 09/13/2023] [Accepted: 10/12/2023] [Indexed: 05/05/2024] Open
Abstract
Neurons in the medial superior olive (MSO) exhibit high frequency responses such as subthreshold resonance, which is helpful to sensitively detect a small difference in the arrival time of sounds between two ears for precise sound localization. Recently, except for the high frequency depolarization resonance mediated by a low threshold potassium (IKLT) current, a low frequency hyperpolarization resonance mediated by a hyperpolarization-activated cation (IH) current is observed in experiments on the MSO neurons, forming double resonances. The complex dynamics underlying double resonances are studied in an MSO neuron model in the present paper. Firstly, double resonances similar to the experimental observations are simulated as the resting membrane potential is between half-activation voltages of IH and IKLT currents, and stimulation current (IZAP) with large amplitude and exponentially increasing frequency is applied. Secondly, multiple effective factors to modulate double resonances are obtained. Especially, the decrease of time constant of IKLT current and increase of conductance of IH and IKLT currents can enhance the depolarization resonance frequency for precise sound localization. Last, different frequency responses of slow IH and fast IKLT currents in formation of the resonances are acquired. A middle phase difference between IZAP and IKLT currents appears at a high frequency, and the interaction between the positive part of IZAP and the negative IKLT current forms the depolarization resonance. Interaction between the negative part of IZAP and positive IH current with a middle phase difference results in hyperpolarization resonance at a low frequency. Furthermore, the phase difference between IZAP and resonance current can well explain the increase of depolarization resonance frequency modulated by the increase of conductance of IH or IKLT currents. The results present the dynamical and biophysical mechanisms for the double resonances mediated by two currents in the MSO neurons, which is helpful to enhance the depolarization resonance frequency for precise sound localization.
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Affiliation(s)
- Runxia Wang
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai, 200092 China
| | - Huaguang Gu
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai, 200092 China
| | - Xinjing Zhang
- School of Mathematics and Statistics, North China University of Water Resources and Electric Power, Zhengzhou, 450000 China
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Li YH, Joris PX. Case reopened: A temporal basis for harmonic pitch templates in the early auditory system?a). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 154:3986-4003. [PMID: 38149819 DOI: 10.1121/10.0023969] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 12/04/2023] [Indexed: 12/28/2023]
Abstract
A fundamental assumption of rate-place models of pitch is the existence of harmonic templates in the central nervous system (CNS). Shamma and Klein [(2000). J. Acoust. Soc. Am. 107, 2631-2644] hypothesized that these templates have a temporal basis. Coincidences in the temporal fine-structure of neural spike trains, even in response to nonharmonic, stochastic stimuli, would be sufficient for the development of harmonic templates. The physiological plausibility of this hypothesis is tested. Responses to pure tones, low-pass noise, and broadband noise from auditory nerve fibers and brainstem "high-sync" neurons are studied. Responses to tones simulate the output of fibers with infinitely sharp filters: for these responses, harmonic structure in a coincidence matrix comparing pairs of spike trains is indeed found. However, harmonic template structure is not observed in coincidences across responses to broadband noise, which are obtained from nerve fibers or neurons with enhanced synchronization. Using a computer model based on that of Shamma and Klein, it is shown that harmonic templates only emerge when consecutive processing steps (cochlear filtering, lateral inhibition, and temporal enhancement) are implemented in extreme, physiologically implausible form. It is concluded that current physiological knowledge does not support the hypothesis of Shamma and Klein (2000).
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Affiliation(s)
- Yi-Hsuan Li
- Laboratory of Auditory Neurophysiology, Medical School, Campus Gasthuisberg, University of Leuven, B-3000 Leuven, Belgium
| | - Philip X Joris
- Laboratory of Auditory Neurophysiology, Medical School, Campus Gasthuisberg, University of Leuven, B-3000 Leuven, Belgium
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Zhang X, Hedwig B. Sound processing in the cricket brain: evidence for a pulse duration filter. J Neurophysiol 2023; 130:953-966. [PMID: 37701942 PMCID: PMC10649838 DOI: 10.1152/jn.00252.2023] [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: 06/26/2023] [Revised: 08/28/2023] [Accepted: 08/28/2023] [Indexed: 09/14/2023] Open
Abstract
The auditory system of female crickets allows them to specifically recognize and approach the species-specific male calling song, defined by sound pulses and silent intervals. Auditory brain neurons form a delay-line and coincidence detector network tuned to the pulse period of the male song. We analyzed the impact of changes in pulse duration on the behavior and the responses of the auditory neurons and the network. We confirm that the ascending neuron AN1 and the local neuron LN2 copy the temporal structure of the song. During ongoing long sound pulses, the delay-line neuron LN5 shows additional rebound responses and the coincidence detector neuron LN3 can generate additional bursts of activity, indicating that these may be driven by intrinsic oscillations of the network. Moreover, the response of the feature detector neuron LN4 is shaped by a combination of inhibitory and excitatory synaptic inputs, and LN4 responds even to long sound pulses with a short depolarization and burst of spikes, like to a sound pulse of natural duration. This response property of LN4 indicates a selective auditory pulse duration filter mechanism of the pattern recognition network, which is tuned to the duration of natural pulses. Comparing the tuning of the phonotactic behavior with the tuning of the local auditory brain neurons to the same test patterns, we find no evidence that a modulation of the phonotactic behavior is reflected at the level of the feature detector neurons. This rather suggests that steering to nonattractive pulse patterns is organized at the thoracic level.NEW & NOTEWORTHY Pulse period selectivity has been reported for the cricket delay-line and coincidence detector network, whereas pulse duration selectivity is evident from behavioral tests. Pulses of increasing duration elicit responses in the pattern recognition neurons, which do not parallel the behavioral responses and indicate additional processing mechanisms. Long sound pulses elicit rhythmic rebound activity and additional bursts, whereas the feature detector neuron reveals a pulse duration filter, expanding our understanding of the pattern recognition process.
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Affiliation(s)
- Xinyang Zhang
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Berthold Hedwig
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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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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Mackenbach Y, Borst JGG. Somatic Integration of Incoherent Dendritic Inputs in the Gerbil Medial Superior Olive. J Neurosci 2023; 43:4093-4109. [PMID: 37130779 PMCID: PMC10255013 DOI: 10.1523/jneurosci.2215-22.2023] [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: 11/30/2022] [Revised: 04/11/2023] [Accepted: 04/14/2023] [Indexed: 05/04/2023] Open
Abstract
The medial superior olive (MSO) is a binaural nucleus that is specialized in detecting the relative arrival times of sounds at both ears. Excitatory inputs to its neurons originating from either ear are segregated to different dendrites. To study the integration of synaptic inputs both within and between dendrites, we made juxtacellular and whole-cell recordings from the MSO in anesthetized female gerbils, while presenting a "double zwuis" stimulus, in which each ear received its own set of tones, which were chosen in a way that all second-order distortion products (DP2s) could be uniquely identified. MSO neurons phase-locked to multiple tones within the multitone stimulus, and vector strength, a measure for spike phase-locking, generally depended linearly on the size of the average subthreshold response to a tone. Subthreshold responses to tones in one ear depended little on the presence of sound in the other ear, suggesting that inputs from different ears sum linearly without a substantial role for somatic inhibition. The "double zwuis" stimulus also evoked response components in the MSO neuron that were phase-locked to DP2s. Bidendritic subthreshold DP2s were quite rare compared with bidendritic suprathreshold DP2s. We observed that in a small subset of cells, the ability to trigger spikes differed substantially between both ears, which might be explained by a dendritic axonal origin. Some neurons that were driven monaurally by only one of the two ears nevertheless showed decent binaural tuning. We conclude that MSO neurons are remarkably good in finding binaural coincidences even among uncorrelated inputs.SIGNIFICANCE STATEMENT Neurons in the medial superior olive are essential for precisely localizing low-frequency sounds in the horizontal plane. From their soma, only two dendrites emerge, which are innervated by inputs originating from different ears. Using a new sound stimulus, we studied the integration of inputs both within and between these dendrites in unprecedented detail. We found evidence that inputs from different dendrites add linearly at the soma, but that small increases in somatic potentials could lead to large increases in the probability of generating a spike. This basic scheme allowed the MSO neurons to detect the relative arrival time of inputs at both dendrites remarkably efficient, although the relative size of these inputs could differ considerably.
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Affiliation(s)
- Yarmo Mackenbach
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, 3000 CA, The Netherlands
| | - J Gerard G Borst
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, 3000 CA, The Netherlands
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Carr CE, Wang T, Kraemer I, Capshaw G, Ashida G, Koeppl C, Kempter R, Kuokkanen PT. Experience-Dependent Plasticity in Nucleus Laminaris of the Barn Owl. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526884. [PMID: 36778252 PMCID: PMC9915572 DOI: 10.1101/2023.02.02.526884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Barn owls experience increasing interaural time differences (ITDs) during development, because their head width more than doubles in the month after hatching. We therefore hypothesized that their ITD detection circuit might be modified by experience. To test this, we raised owls with unilateral ear inserts that delayed and attenuated the acoustic signal, then measured the ITD representation in the brainstem nucleus laminaris (NL) when they were adult. The ITD circuit is composed of delay line inputs to coincidence detectors, and we predicted that plastic changes would lead to shorter delays in the axons from the manipulated ear, and complementary shifts in ITD representation on the two sides. In owls that received ear inserts starting around P14, the maps of ITD shifted in the predicted direction, but only on the ipsilateral side, and only in those tonotopic regions that had not experienced auditory stimulation prior to insertion. The contralateral map did not change. Experience-dependent plasticity of the ITD circuit occurs in NL, and our data suggest that ipsilateral and contralateral delays are independently regulated. Thus, altered auditory input during development leads to long-lasting changes in the representation of ITD.
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9
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Drucker B, Goldwyn JH. Structure and dynamics that specialize neurons for high-frequency coincidence detection in the barn owl nucleus laminaris. BIOLOGICAL CYBERNETICS 2023; 117:143-162. [PMID: 37129628 DOI: 10.1007/s00422-023-00962-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 03/14/2023] [Indexed: 05/03/2023]
Abstract
A principal cue for sound source localization is the difference in arrival times of sounds at an animal's two ears (interaural time difference, ITD). Neurons that process ITDs are specialized to compare the timing of inputs with submillisecond precision. In the barn owl, ITD processing begins in the nucleus laminaris (NL) region of the auditory brain stem. Remarkably, NL neurons are sensitive to ITDs in high-frequency sounds (kilohertz-range). This contrasts with ITD-based sound localization in analogous regions in mammals where ITD sensitivity is typically restricted to lower-frequency sounds. Guided by previous experiments and modeling studies of tone-evoked responses of NL neurons, we propose NL neurons achieve high-frequency ITD sensitivity if they respond selectively to the small-amplitude, high-frequency oscillations in their inputs, and remain relatively non-responsive to mean input level. We use a biophysically based model to study the effects of soma-axon coupling on dynamics and function in NL neurons. First, we show that electrical separation of the soma from the axon region in the neuron enhances high-frequency ITD sensitivity. This soma-axon coupling configuration promotes linear subthreshold dynamics and rapid spike initiation, making the model more responsive to input oscillations, rather than mean input level. Second, we provide new evidence for the essential role of phasic dynamics for high-frequency neural coincidence detection. Transforming our model to the phasic firing mode further tunes the model to respond selectively to the oscillating inputs that carry ITD information. Similar structural and dynamical mechanisms specialize mammalian auditory brain stem neurons for ITD sensitivity, and thus, our work identifies common principles of ITD processing and neural coincidence detection across species and for sounds at widely different frequencies.
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Affiliation(s)
- Ben Drucker
- Department of Mathematics and Statistics, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA
- Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA, 10587, USA
| | - Joshua H Goldwyn
- Department of Mathematics and Statistics, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA.
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Wang J, Xu J, Wu J, Xu Q. Geometric characterization of dynamical structure for neural firing activities induced by inhibitory pulse. Cogn Neurodyn 2022; 16:1505-1524. [PMID: 36408077 PMCID: PMC9666638 DOI: 10.1007/s11571-022-09799-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 11/25/2022] Open
Abstract
In general, inhibitory stimuli are thought to inhibit neuronal firing, but they may actually enhance firing sometimes, such as post-inhibitory rebound spike (PIR spike) and post-inhibitory facilitation (PIF) phenomena, which play an important role in human neuronal activities. We study responses to inhibitory pulse in a classical neuron model (Quartic adaptive Integrate-and-fire model) well known to reproduce a number of biologically realistic behaviors. The three phenomena that we study are PIR, in which a neuron fires after an inhibitory pulse, and PIF, in which a subthreshold excitatory input can induce a spike if it is applied with proper timing after an inhibitory pulse, as well as period firing after inhibitory pulse. When the system features focus and saddle two equilibriums, the three phenomena will be occurred under the inhibitory pulse, while all three phenomena will not be induced when the system features node and saddle two equilibriums. Using dynamical systems theory, we explain the threshold mechanism of enhancement of neural firing response induced by inhibitory pulse and analyze the origin of these phenomena from several factors. We also describe the geometric characterization of dynamical structures of these three phenomena. This study therefore enrich the paradoxical phenomena that induced by inhibitory input and advance our understanding of its role.
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Affiliation(s)
- Junjie Wang
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
| | - Jieqiong Xu
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
- Scientific Research Center of Engineering Mechanics, Guangxi University, Nanning, 530004 China
| | - Jianmei Wu
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
| | - Qixiang Xu
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
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11
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Mammalian octopus cells are direction selective to frequency sweeps by excitatory synaptic sequence detection. Proc Natl Acad Sci U S A 2022; 119:e2203748119. [PMID: 36279465 PMCID: PMC9636937 DOI: 10.1073/pnas.2203748119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Octopus cells are remarkable projection neurons of the mammalian cochlear nucleus, with extremely fast membranes and wide-frequency tuning. They are considered prime examples of coincidence detectors but are poorly characterized in vivo. We discover that octopus cells are selective to frequency sweep direction, a feature that is absent in their auditory nerve inputs. In vivo intracellular recordings reveal that direction selectivity does not derive from across-frequency coincidence detection but hinges on the amplitudes and activation sequence of auditory nerve inputs tuned to clusters of hot spot frequencies. A simple biophysical octopus cell model excited with real nerve spike trains recreates direction selectivity through interaction of intrinsic membrane conductances with the activation sequence of clustered excitatory inputs. We conclude that octopus cells are sequence detectors, sensitive to temporal patterns across cochlear frequency channels. The detection of sequences rather than coincidences is a much simpler but powerful operation to extract temporal information.
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Pätz C, Console-Meyer L, Felmy F. Structural arrangement of auditory brainstem nuclei in the bats Phyllostomus discolor and Carollia perspicillata. J Comp Neurol 2022; 530:2762-2781. [PMID: 35703441 DOI: 10.1002/cne.25355] [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: 10/06/2021] [Revised: 04/24/2022] [Accepted: 05/14/2022] [Indexed: 11/10/2022]
Abstract
The structure of the mammalian auditory brainstem is evolutionarily highly plastic, and distinct nuclei arrange in a species-dependent manner. Such anatomical variability is present in the superior olivary complex (SOC) and the nuclei of the lateral lemniscus (LL). Due to the structure-function relationship in the auditory brainstem, the identification of individual nuclei supports the understanding of sound processing. Here, we comparatively describe the nucleus arrangement and the expression of functional markers in the auditory brainstem of the two bat species Phyllostomus discolor and Carollia perspicillata. Using immunofluorescent labeling, we describe the arrangement and identity of the SOC and LL nuclei based on the expression of synaptic markers (vesicular glutamate transporter 1 and glycine transporter 2), calcium-binding proteins, as well as the voltage-gated ion channel subunits Kv1.1 and HCN1. The distribution of excitatory and inhibitory synaptic labeling appears similar between both species and matches with that of other mammals. The detection of calcium-binding proteins indicates species-dependent differences and deviations from other mammals. Kv1.1 and HCN1 show largely the same expression pattern in both species, which diverges from other mammals, indicating functional adaptations in the cellular physiology of bat neurons.
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Affiliation(s)
- Christina Pätz
- Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Laura Console-Meyer
- Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Felix Felmy
- Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany
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13
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Yamada R, Kuba H. Cellular Strategies for Frequency-Dependent Computation of Interaural Time Difference. Front Synaptic Neurosci 2022; 14:891740. [PMID: 35602551 PMCID: PMC9120351 DOI: 10.3389/fnsyn.2022.891740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Binaural coincidence detection is the initial step in encoding interaural time differences (ITDs) for sound-source localization. In birds, neurons in the nucleus laminaris (NL) play a central role in this process. These neurons receive excitatory synaptic inputs on dendrites from both sides of the cochlear nucleus and compare their coincidences at the soma. The NL is tonotopically organized, and individual neurons receive a pattern of synaptic inputs that are specific to their tuning frequency. NL neurons differ in their dendritic morphology along the tonotopic axis; their length increases with lower tuning frequency. In addition, our series of studies have revealed several frequency-dependent refinements in the morphological and biophysical characteristics of NL neurons, such as the amount and subcellular distribution of ion channels and excitatory and inhibitory synapses, which enable the neurons to process the frequency-specific pattern of inputs appropriately and encode ITDs at each frequency band. In this review, we will summarize these refinements of NL neurons and their implications for the ITD coding. We will also discuss the similarities and differences between avian and mammalian coincidence detectors.
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14
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Li BZ, Pun SH, Vai MI, Lei TC, Klug A. Predicting the Influence of Axon Myelination on Sound Localization Precision Using a Spiking Neural Network Model of Auditory Brainstem. Front Neurosci 2022; 16:840983. [PMID: 35360169 PMCID: PMC8964079 DOI: 10.3389/fnins.2022.840983] [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: 12/21/2021] [Accepted: 02/18/2022] [Indexed: 01/12/2023] Open
Abstract
Spatial hearing allows animals to rapidly detect and localize auditory events in the surrounding environment. The auditory brainstem plays a central role in processing and extracting binaural spatial cues through microsecond-precise binaural integration, especially for detecting interaural time differences (ITDs) of low-frequency sounds at the medial superior olive (MSO). A series of mechanisms exist in the underlying neural circuits for preserving accurate action potential timing across multiple fibers, synapses and nuclei along this pathway. One of these is the myelination of afferent fibers that ensures reliable and temporally precise action potential propagation in the axon. There are several reports of fine-tuned myelination patterns in the MSO circuit, but how specifically myelination influences the precision of sound localization remains incompletely understood. Here we present a spiking neural network (SNN) model of the Mongolian gerbil auditory brainstem with myelinated axons to investigate whether different axon myelination thicknesses alter the sound localization process. Our model demonstrates that axon myelin thickness along the contralateral pathways can substantially modulate ITD detection. Furthermore, optimal ITD sensitivity is reached when the MSO receives contralateral inhibition via thicker myelinated axons compared to contralateral excitation, a result that is consistent with previously reported experimental observations. Our results suggest specific roles of axon myelination for extracting temporal dynamics in ITD decoding, especially in the pathway of the contralateral inhibition.
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Affiliation(s)
- Ben-Zheng Li
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Electrical Engineering, University of Colorado, Denver, Denver, CO, United States,State Key Laboratory of Analog and Mixed Signal Very-Large-Scale Integration (VLSI), University of Macau, Taipa, Macau SAR, China,Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Taipa, Macau SAR, China
| | - Sio Hang Pun
- State Key Laboratory of Analog and Mixed Signal Very-Large-Scale Integration (VLSI), University of Macau, Taipa, Macau SAR, China
| | - Mang I. Vai
- State Key Laboratory of Analog and Mixed Signal Very-Large-Scale Integration (VLSI), University of Macau, Taipa, Macau SAR, China,Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Taipa, Macau SAR, China
| | - Tim C. Lei
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Electrical Engineering, University of Colorado, Denver, Denver, CO, United States
| | - Achim Klug
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States,*Correspondence: Achim Klug,
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15
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Yamada R, Kuba H. Dendritic synapse geometry optimizes binaural computation in a sound localization circuit. SCIENCE ADVANCES 2021; 7:eabh0024. [PMID: 34818046 PMCID: PMC8612683 DOI: 10.1126/sciadv.abh0024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 10/05/2021] [Indexed: 06/13/2023]
Abstract
Clustering of synapses allows neurons to overcome attenuation of electrical signals at dendrites. However, we show in avian binaural coincidence detectors computing interaural time difference for sound localization that clustering of synapses rather promotes the dendritic attenuation but augments the intensity tolerance of the binaural computations. Using glutamate uncaging, we found in the neurons that synapses were clustered at distal dendritic branches. Modeling revealed that this strengthened sublinear integration within a dendritic tree but enabled the integration of signals from different trees when inputs grow stronger, preventing monoaural output and maintaining the dynamic range of binaural computation. The extent of this clustering differed according to dendritic length and frequency tuning of neurons, being most prominent for long dendrites and low-frequency tuning. This ensures binaural spatial hearing for wide intensity and frequency ranges, highlighting the importance of coupling of synapse geometry with dendritic morphology and input frequency in sensory signal processing.
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16
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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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17
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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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18
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Auditory Brainstem Models: Adapting Cochlear Nuclei Improve Spatial Encoding by the Medial Superior Olive in Reverberation. J Assoc Res Otolaryngol 2021; 22:289-318. [PMID: 33861395 DOI: 10.1007/s10162-021-00797-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/22/2021] [Indexed: 10/21/2022] Open
Abstract
Listeners typically perceive a sound as originating from the direction of its source, even as direct sound is followed milliseconds later by reflected sound from multiple different directions. Early-arriving sound is emphasised in the ascending auditory pathway, including the medial superior olive (MSO) where binaural neurons encode the interaural-time-difference (ITD) cue for spatial location. Perceptually, weighting of ITD conveyed during rising sound energy is stronger at 600 Hz than at 200 Hz, consistent with the minimum stimulus rate for binaural adaptation, and with the longer reverberation times at 600 Hz, compared with 200 Hz, in many natural outdoor environments. Here, we computationally explore the combined efficacy of adaptation prior to the binaural encoding of ITD cues, and excitatory binaural coincidence detection within MSO neurons, in emphasising ITDs conveyed in early-arriving sound. With excitatory inputs from adapting, nonlinear model spherical bushy cells (SBCs) of the bilateral cochlear nuclei, a nonlinear model MSO neuron with low-threshold potassium channels reproduces the rate-dependent emphasis of rising vs. peak sound energy in ITD encoding; adaptation is equally effective in the model MSO. Maintaining adaptation in model SBCs, and adjusting membrane speed in model MSO neurons, 'left' and 'right' populations of computationally efficient, linear model SBCs and MSO neurons reproduce this stronger weighting of ITD conveyed during rising sound energy at 600 Hz compared to 200 Hz. This hemispheric population model demonstrates a link between strong weighting of spatial information during rising sound energy, and correct unambiguous lateralisation of a speech source in reverberation.
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19
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Ma H, Jia B, Li Y, Gu H. Excitability and Threshold Mechanism for Enhanced Neuronal Response Induced by Inhibition Preceding Excitation. Neural Plast 2021; 2021:6692411. [PMID: 33531892 PMCID: PMC7837794 DOI: 10.1155/2021/6692411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/02/2020] [Accepted: 01/06/2021] [Indexed: 11/18/2022] Open
Abstract
Postinhibitory facilitation (PIF) of neural firing presents a paradoxical phenomenon that the inhibitory effect induces enhancement instead of reduction of the firing activity, which plays important roles in sound location of the auditory nervous system, awaited theoretical explanations. In the present paper, excitability and threshold mechanism for the PIF phenomenon is presented in the Morris-Lecar model with type I, II, and III excitabilities. Firstly, compared with the purely excitatory stimulations applied to the steady state, the inhibitory preceding excitatory stimulation to form pairs induces the firing rate increased for type II and III excitabilities instead of type I excitability, when the interval between the inhibitory and excitatory stimulation within each pair is suitable. Secondly, the threshold mechanism for the PIF phenomenon is acquired. For type II and III excitabilities, the inhibitory stimulation induces subthreshold oscillations around the steady state. During the middle and ending phase of the ascending part and the beginning phase of the descending part within a period of the subthreshold oscillations, the threshold to evoke an action potential by an excitatory stimulation becomes weaker, which is the cause for the PIF phenomenon. Last, a theoretical estimation for the range of the interval between the inhibitory and excitatory stimulation for the PIF phenomenon is acquired, which approximates half of the intrinsic period of the subthreshold oscillations for the relatively strong stimulations and becomes narrower for the relatively weak stimulations. The interval for the PIF phenomenon is much shorter for type III excitability, which is closer to the experiment observation, due to the shorter period of the subthreshold oscillations. The results present the excitability and threshold mechanism for the PIF phenomenon, which provide comprehensive and deep explanations to the PIF phenomenon.
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Affiliation(s)
- Hanqing Ma
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
| | - Bing Jia
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
| | - Yuye Li
- College of Mathematics and Computer Science, Chifeng University, Chifeng 024000, China
| | - Huaguang Gu
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
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20
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Arrangement of Excitatory Synaptic Inputs on Dendrites of the Medial Superior Olive. J Neurosci 2021; 41:269-283. [PMID: 33208467 DOI: 10.1523/jneurosci.1055-20.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 11/05/2020] [Accepted: 11/10/2020] [Indexed: 11/21/2022] Open
Abstract
Neurons in the medial superior olive (MSO) detect 10 µs differences in the arrival times of a sound at the two ears. Such acuity requires exquisitely precise integration of binaural synaptic inputs. There is substantial understanding of how neuronal phase locking of afferent MSO structures, and MSO membrane biophysics subserve such high precision. However, we still lack insight into how the entirety of excitatory inputs is integrated along the MSO dendrite under sound stimulation. To understand how the dendrite integrates excitatory inputs as a whole, we combined anatomic quantifications of the afferent innervation in gerbils of both sexes with computational modeling of a single cell. We present anatomic data from confocal and transmission electron microscopy showing that single afferent fibers follow a single dendrite mostly up to the soma and contact it at multiple (median 4) synaptic sites, each containing multiple independent active zones (the overall density of active zones is estimated as 1.375 per μm2). Thus, any presynaptic action potential may elicit temporally highly coordinated synaptic vesicle release at tens of active zones, thereby achieving secure transmission. Computer simulations suggest that such an anatomic arrangement boosts the amplitude and sharpens the time course of excitatory postsynaptic potentials by reducing current sinks and more efficiently recruiting subthreshold potassium channels. Both effects improve binaural coincidence detection compared with single large synapses at the soma. Our anatomic data further allow for estimation of a lower bound of 7 and an upper bound of 70 excitatory fibers per dendrite.SIGNIFICANCE STATEMENT Passive dendritic propagation attenuates the amplitude of postsynaptic potentials and widens their temporal spread. Neurons in the medial superior olive, with their large bilateral dendrites, however, can detect coincidence of binaural auditory inputs with submillisecond precision, a computation that is in stark contrast to passive dendritic processing. Here, we show that dendrites can counteract amplitude attenuation and even decrease the temporal spread of postsynaptic potentials, if active subthreshold potassium conductances are triggered in temporal coordination along the whole dendrite. Our anatomic finding that axons run in parallel to the dendrites and make multiple synaptic contacts support such coordination since incoming action potentials would depolarize the dendrite at multiple sites within a brief time interval.
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21
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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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22
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Mechanisms and Functional Consequences of Presynaptic Homeostatic Plasticity at Auditory Nerve Synapses. J Neurosci 2020; 40:6896-6909. [PMID: 32747441 DOI: 10.1523/jneurosci.1175-19.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 07/24/2020] [Accepted: 07/28/2020] [Indexed: 01/21/2023] Open
Abstract
Multiple forms of homeostasis influence synaptic function under diverse activity conditions. Both presynaptic and postsynaptic forms of homeostasis are important, but their relative impact on fidelity is unknown. To address this issue, we studied auditory nerve synapses onto bushy cells in the cochlear nucleus of mice of both sexes. These synapses undergo bidirectional presynaptic and postsynaptic homeostatic changes with increased and decreased acoustic stimulation. We found that both young and mature synapses exhibit similar activity-dependent changes in short-term depression. Experiments using chelators and imaging both indicated that presynaptic Ca2+ influx decreased after noise exposure, and increased after ligating the ear canal. By contrast, Ca2+ cooperativity was unaffected. Experiments using specific antagonists suggest that occlusion leads to changes in the Ca2+ channel subtypes driving neurotransmitter release. Furthermore, dynamic-clamp experiments revealed that spike fidelity primarily depended on changes in presynaptic depression, with some contribution from changes in postsynaptic intrinsic properties. These experiments indicate that presynaptic Ca2+ influx is homeostatically regulated in vivo to enhance synaptic fidelity.SIGNIFICANCE STATEMENT Homeostatic mechanisms in synapses maintain stable function in the face of different levels of activity. Both juvenile and mature auditory nerve synapses onto bushy cells modify short-term depression in different acoustic environments, which raises the question of what the underlying presynaptic mechanisms are and the relative importance of presynaptic and postsynaptic contributions to the faithful transfer of information. Changes in short-term depression under different acoustic conditions were a result of changes in presynaptic Ca2+ influx. Spike fidelity was affected by both presynaptic and postsynaptic changes after ear occlusion and was only affected by presynaptic changes after noise-rearing. These findings are important for understanding regulation of auditory synapses under normal conditions and also in disorders following noise exposure or conductive hearing loss.
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23
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Spiking network optimized for word recognition in noise predicts auditory system hierarchy. PLoS Comput Biol 2020; 16:e1007558. [PMID: 32559204 PMCID: PMC7329140 DOI: 10.1371/journal.pcbi.1007558] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/01/2020] [Accepted: 11/22/2019] [Indexed: 11/21/2022] Open
Abstract
The auditory neural code is resilient to acoustic variability and capable of recognizing sounds amongst competing sound sources, yet, the transformations enabling noise robust abilities are largely unknown. We report that a hierarchical spiking neural network (HSNN) optimized to maximize word recognition accuracy in noise and multiple talkers predicts organizational hierarchy of the ascending auditory pathway. Comparisons with data from auditory nerve, midbrain, thalamus and cortex reveals that the optimal HSNN predicts several transformations of the ascending auditory pathway including a sequential loss of temporal resolution and synchronization ability, increasing sparseness, and selectivity. The optimal organizational scheme enhances performance by selectively filtering out noise and fast temporal cues such as voicing periodicity, that are not directly relevant to the word recognition task. An identical network arranged to enable high information transfer fails to predict auditory pathway organization and has substantially poorer performance. Furthermore, conventional single-layer linear and nonlinear receptive field networks that capture the overall feature extraction of the HSNN fail to achieve similar performance. The findings suggest that the auditory pathway hierarchy and its sequential nonlinear feature extraction computations enhance relevant cues while removing non-informative sources of noise, thus enhancing the representation of sounds in noise impoverished conditions. The brain’s ability to recognize sounds in the presence of competing sounds or background noise is essential for everyday hearing tasks. How the brain accomplishes noise resiliency, however, is poorly understood. Using neural recordings from the ascending auditory pathway and an auditory spiking network model trained for sound recognition in noise we explore the computational strategies that enable noise robustness. Our results suggest that the hierarchical feature organization of the ascending auditory pathway and the resulting computations are critical for sound recognition in the presence of noise.
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24
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Linneweber GA, Andriatsilavo M, Dutta SB, Bengochea M, Hellbruegge L, Liu G, Ejsmont RK, Straw AD, Wernet M, Hiesinger PR, Hassan BA. A neurodevelopmental origin of behavioral individuality in the Drosophila visual system. Science 2020; 367:1112-1119. [DOI: 10.1126/science.aaw7182] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 09/26/2019] [Accepted: 01/27/2020] [Indexed: 01/10/2023]
Abstract
The genome versus experience dichotomy has dominated understanding of behavioral individuality. By contrast, the role of nonheritable noise during brain development in behavioral variation is understudied. Using Drosophila melanogaster, we demonstrate a link between stochastic variation in brain wiring and behavioral individuality. A visual system circuit called the dorsal cluster neurons (DCN) shows nonheritable, interindividual variation in right/left wiring asymmetry and controls object orientation in freely walking flies. We show that DCN wiring asymmetry instructs an individual’s object responses: The greater the asymmetry, the better the individual orients toward a visual object. Silencing DCNs abolishes correlations between anatomy and behavior, whereas inducing DCN asymmetry suffices to improve object responses.
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25
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Ewert SD, Paraouty N, Lorenzi C. A two‐path model of auditory modulation detection using temporal fine structure and envelope cues. Eur J Neurosci 2020; 51:1265-1278. [DOI: 10.1111/ejn.13846] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Stephan D. Ewert
- Medizinische Physik and Cluster of Excellence Hearing4All Universität Oldenburg 26111 Oldenburg Germany
| | - Nihaad Paraouty
- Laboratoire des systèmes perceptifs Département d’études cognitives, École normale supérieure CNRS PSL Research University Paris France
| | - Christian Lorenzi
- Laboratoire des systèmes perceptifs Département d’études cognitives, École normale supérieure CNRS PSL Research University Paris France
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26
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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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27
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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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28
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Rankin J, Rinzel J. Computational models of auditory perception from feature extraction to stream segregation and behavior. Curr Opin Neurobiol 2019; 58:46-53. [PMID: 31326723 DOI: 10.1016/j.conb.2019.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 06/22/2019] [Indexed: 10/26/2022]
Abstract
Audition is by nature dynamic, from brainstem processing on sub-millisecond time scales, to segregating and tracking sound sources with changing features, to the pleasure of listening to music and the satisfaction of getting the beat. We review recent advances from computational models of sound localization, of auditory stream segregation and of beat perception/generation. A wealth of behavioral, electrophysiological and imaging studies shed light on these processes, typically with synthesized sounds having regular temporal structure. Computational models integrate knowledge from different experimental fields and at different levels of description. We advocate a neuromechanistic modeling approach that incorporates knowledge of the auditory system from various fields, that utilizes plausible neural mechanisms, and that bridges our understanding across disciplines.
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Affiliation(s)
- James Rankin
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Harrison Building, North Park Rd, Exeter EX4 4QF, UK.
| | - John Rinzel
- Center for Neural Science, New York University, 4 Washington Place, 10003 New York, NY, United States; Courant Institute of Mathematical Sciences, New York University, 251 Mercer St, 10012 New York, NY, United States
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29
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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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30
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Kurenkov A, DuttaGupta S, Zhang C, Fukami S, Horio Y, Ohno H. Artificial Neuron and Synapse Realized in an Antiferromagnet/Ferromagnet Heterostructure Using Dynamics of Spin-Orbit Torque Switching. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900636. [PMID: 30989740 DOI: 10.1002/adma.201900636] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/25/2019] [Indexed: 06/09/2023]
Abstract
Efficient information processing in the human brain is achieved by dynamics of neurons and synapses, motivating effective implementation of artificial spiking neural networks. Here, the dynamics of spin-orbit torque switching in antiferromagnet/ferromagnet heterostructures is studied to show the capability of the material system to form artificial neurons and synapses for asynchronous spiking neural networks. The magnetization switching, driven by a single current pulse or trains of pulses, is examined as a function of the pulse width (1 s to 1 ns), amplitude, number, and pulse-to-pulse interval. Based on this dynamics and the unique ability of the system to exhibit binary or analog behavior depending on the device size, key functionalities of a synapse (spike-timing-dependent plasticity) and a neuron (leaky integrate-and-fire) are reproduced in the same material and on the basis of the same working principle. These results open a way toward spintronics-based neuromorphic hardware that executes cognitive tasks with the efficiency of the human brain.
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Affiliation(s)
- Aleksandr Kurenkov
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics (Core Research Cluster), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Samik DuttaGupta
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics (Core Research Cluster), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Chaoliang Zhang
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai, 980-8578, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai, 980-0845, Japan
| | - Shunsuke Fukami
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics (Core Research Cluster), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai, 980-0845, Japan
- WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Yoshihiko Horio
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Hideo Ohno
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics (Core Research Cluster), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai, 980-0845, Japan
- WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
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31
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Kettler L, Carr CE. Neural Maps of Interaural Time Difference in the American Alligator: A Stable Feature in Modern Archosaurs. J Neurosci 2019; 39:3882-3896. [PMID: 30886018 PMCID: PMC6520516 DOI: 10.1523/jneurosci.2989-18.2019] [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: 11/26/2018] [Revised: 02/20/2019] [Accepted: 02/23/2019] [Indexed: 11/21/2022] Open
Abstract
Detection of interaural time differences (ITDs) is crucial for sound localization in most vertebrates. The current view is that optimal computational strategies of ITD detection depend mainly on head size and available frequencies, although evolutionary history should also be taken into consideration. In archosaurs, which include birds and crocodiles, the brainstem nucleus laminaris (NL) developed into the critical structure for ITD detection. In birds, ITDs are mapped in an orderly array or place code, whereas in the mammalian medial superior olive, the analog of NL, maps are not found. As yet, in crocodilians, topographical representations have not been identified. However, nontopographic representations of ITD cannot be excluded due to different anatomical and ethological features of birds and crocodiles. Therefore, we measured ITD-dependent responses in the NL of anesthetized American alligators of either sex and identified the location of the recording sites by lesions made after recording. The measured extracellular field potentials, or neurophonics, were strongly ITD tuned, and their preferred ITDs correlated with the position in NL. As in birds, delay lines, which compensate for external time differences, formed maps of ITD. The broad distributions of best ITDs within narrow frequency bands were not consistent with an optimal coding model. We conclude that the available acoustic cues and the architecture of the acoustic system in early archosaurs led to a stable and similar organization in today's birds and crocodiles, although physical features, such as internally coupled ears, head size, or shape, and audible frequency range, vary among the two groups.SIGNIFICANCE STATEMENT Interaural time difference (ITD) is an important cue for sound localization, and the optimal strategies for encoding ITD in neuronal populations are the subject of ongoing debate. We show that alligators form maps of ITD very similar to birds, suggesting that their common archosaur ancestor reached a stable coding solution different from mammals. Mammals and diapsids evolved tympanic hearing independently, and local optima can be reached in evolution that are not considered by global optimal coding models. Thus, the presence of ITD maps in the brainstem may reflect a local optimum in evolutionary development. Our results underline the importance of comparative animal studies and show that optimal models must be viewed in the light of evolutionary processes.
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Affiliation(s)
- Lutz Kettler
- Lehrstuhl für Zoologie, Technische Universität München, 85354 Freising, Germany, and
| | - Catherine E Carr
- Department of Biology, University of Maryland, College Park, Maryland 20742
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32
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Zorio DAR, Monsma S, Sanes DH, Golding NL, Rubel EW, Wang Y. De novo sequencing and initial annotation of the Mongolian gerbil (Meriones unguiculatus) genome. Genomics 2019; 111:441-449. [PMID: 29526484 PMCID: PMC6129228 DOI: 10.1016/j.ygeno.2018.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/26/2018] [Accepted: 03/01/2018] [Indexed: 12/28/2022]
Abstract
The Mongolian gerbil (Meriones unguiculatus) is a member of the rodent family that displays several features not found in mice or rats, including sensory specializations and social patterns more similar to those in humans. These features have made gerbils a valuable animal for research studies of auditory and visual processing, brain development, learning and memory, and neurological disorders. Here, we report the whole gerbil annotated genome sequence, and identify important similarities and differences to the human and mouse genomes. We further analyze the chromosomal structure of eight genes with high relevance for controlling neural signaling and demonstrate a high degree of homology between these genes in mouse and gerbil. This homology increases the likelihood that individual genes can be rapidly identified in gerbil and used for genetic manipulations. The availability of the gerbil genome provides a foundation for advancing our knowledge towards understanding evolution, behavior and neural function in mammals. ACCESSION NUMBER: The Whole Genome Shotgun sequence data from this project has been deposited at DDBJ/ENA/GenBank under the accession NHTI00000000. The version described in this paper is version NHTI01000000. The fragment reads, and mate pair reads have been deposited in the Sequence Read Archive under BioSample accession SAMN06897401.
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Affiliation(s)
- Diego A R Zorio
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA.
| | | | - Dan H Sanes
- Center for Neural Science, New York University, New York, NY, USA
| | - Nace L Golding
- University of Texas at Austin, Department of Neuroscience, Center for Learning and Memory, Austin, TX, USA
| | - Edwin W Rubel
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, USA
| | - Yuan Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA; Program in Neuroscience, Florida State University, Tallahassee, FL, USA.
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33
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Goldwyn JH, Remme MWH, Rinzel J. Soma-axon coupling configurations that enhance neuronal coincidence detection. PLoS Comput Biol 2019; 15:e1006476. [PMID: 30830905 PMCID: PMC6417746 DOI: 10.1371/journal.pcbi.1006476] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 03/14/2019] [Accepted: 01/28/2019] [Indexed: 11/17/2022] Open
Abstract
Coincidence detector neurons transmit timing information by responding preferentially to concurrent synaptic inputs. Principal cells of the medial superior olive (MSO) in the mammalian auditory brainstem are superb coincidence detectors. They encode sound source location with high temporal precision, distinguishing submillisecond timing differences among inputs. We investigate computationally how dynamic coupling between the input region (soma and dendrite) and the spike-generating output region (axon and axon initial segment) can enhance coincidence detection in MSO neurons. To do this, we formulate a two-compartment neuron model and characterize extensively coincidence detection sensitivity throughout a parameter space of coupling configurations. We focus on the interaction between coupling configuration and two currents that provide dynamic, voltage-gated, negative feedback in subthreshold voltage range: sodium current with rapid inactivation and low-threshold potassium current, IKLT. These currents reduce synaptic summation and can prevent spike generation unless inputs arrive with near simultaneity. We show that strong soma-to-axon coupling promotes the negative feedback effects of sodium inactivation and is, therefore, advantageous for coincidence detection. Furthermore, the feedforward combination of strong soma-to-axon coupling and weak axon-to-soma coupling enables spikes to be generated efficiently (few sodium channels needed) and with rapid recovery that enhances high-frequency coincidence detection. These observations detail the functional benefit of the strongly feedforward configuration that has been observed in physiological studies of MSO neurons. We find that IKLT further enhances coincidence detection sensitivity, but with effects that depend on coupling configuration. For instance, in models with weak soma-to-axon and weak axon-to-soma coupling, IKLT in the axon enhances coincidence detection more effectively than IKLT in the soma. By using a minimal model of soma-to-axon coupling, we connect structure, dynamics, and computation. Although we consider the particular case of MSO coincidence detectors, our method for creating and exploring a parameter space of two-compartment models can be applied to other neurons. Brain cells (neurons) are spatially extended structures. The locations at which neurons receive inputs and generate outputs are often distinct. We formulate and study a minimal mathematical model that describes the dynamical coupling between the input and output regions of a neuron. We construct our model to reflect known properties of neurons in the auditory brainstem that play an important role in our ability to locate sound sources. These neurons are known as coincidence detectors because they are most likely to respond when they receive simultaneous inputs. We use simulations to explore coincidence detection sensitivity throughout the parameter space of input-output coupling and to identify the coupling configurations that are best for neural coincidence detection. We find that strong forward coupling (from input region to output region), enhances coincidence detection sensitivity in our model and that low-threshold potassium current further improves coincidence detection. Our study is significant in that we detail how cell structure affects neuronal dynamics and, consequently, the ability of neurons to perform as temporally-precise coincidence detectors.
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Affiliation(s)
- Joshua H Goldwyn
- Department of Mathematics and Statistics, Swarthmore College, Swarthmore, Pennsylvania, United States of America
| | - Michiel W H Remme
- Institute for Theoretical Biology, Humboldt University Berlin, Berlin, Germany
| | - John Rinzel
- Center for Neural Science, New York University, New York, New York, United States of America.,Courant Institute of Mathematical Sciences, New York University, New York, New York, United States of America
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34
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McColgan T, Kuokkanen PT, Carr CE, Kempter R. Dynamics of synaptic extracellular field potentials in the nucleus laminaris of the barn owl. J Neurophysiol 2019; 121:1034-1047. [PMID: 30575430 DOI: 10.1152/jn.00648.2017] [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] [Indexed: 01/20/2023] Open
Abstract
Synaptic currents are frequently assumed to make a major contribution to the extracellular field potential (EFP). However, in any neuronal population, the explicit separation of synaptic sources from other contributions such as postsynaptic spikes remains a challenge. Here we take advantage of the simple organization of the barn owl nucleus laminaris (NL) in the auditory brain stem to isolate synaptic currents through the iontophoretic application of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-receptor antagonist 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[ f]quinoxaline-7-sulfonamide (NBQX). Responses to auditory stimulation show that the temporal dynamics of the evoked synaptic contributions to the EFP are consistent with synaptic short-term depression (STD). The estimated time constants of an STD model fitted to the data are similar to the fast time constants reported from in vitro experiments in the chick. Overall, the putative synaptic EFPs in the barn owl NL are significant but small (<1% change of the variance by NBQX). This result supports the hypothesis that the EFP in NL is generated mainly by axonal spikes, in contrast to most other neuronal systems. NEW & NOTEWORTHY Synaptic currents are assumed to make a major contribution to the extracellular field potential in the brain, but it is hard to directly isolate these synaptic components. Here we take advantage of the simple organization of the barn owl nucleus laminaris in the auditory brain stem to isolate synaptic currents through the iontophoretic application of a synaptic blocker. We show that the responses are consistent with a simple model of short-term synaptic depression.
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Affiliation(s)
- Thomas McColgan
- Bernstein Center for Computational Neuroscience , Berlin , Germany.,Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin , Germany
| | - Paula T Kuokkanen
- Bernstein Center for Computational Neuroscience , Berlin , Germany.,Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin , Germany.,Department of Biology, University of Maryland , College Park, Maryland
| | - Catherine E Carr
- Department of Biology, University of Maryland , College Park, Maryland
| | - Richard Kempter
- Bernstein Center for Computational Neuroscience , Berlin , Germany.,Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin , Germany.,Einstein Center for Neurosciences , Berlin , Germany
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35
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Joris PX. Neural binaural sensitivity at high sound speeds: Single cell responses in cat midbrain to fast-changing interaural time differences of broadband sounds. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 145:EL45. [PMID: 30710960 PMCID: PMC7112706 DOI: 10.1121/1.5087524] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 12/13/2018] [Accepted: 12/18/2018] [Indexed: 06/09/2023]
Abstract
Relative motion between the body and the outside world is a rich source of information. Neural selectivity to motion is well-established in several sensory systems, but is controversial in hearing. This study examines neural sensitivity to changes in the instantaneous interaural time difference of sounds at the two ears. Midbrain neurons track such changes up to extremely high speeds, show only a coarse dependence of firing rate on speed, and lack directional selectivity. These results argue against the presence of selectivity to auditory motion at the level of the midbrain, but reveal an acuity which enables coding of fast-fluctuating binaural cues in realistic sound environments.
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Affiliation(s)
- Philip X Joris
- Laboratory of Auditory Neurophysiology, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium
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36
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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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37
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Franken TP, Joris PX, Smith PH. Principal cells of the brainstem's interaural sound level detector are temporal differentiators rather than integrators. eLife 2018; 7:33854. [PMID: 29901438 PMCID: PMC6063729 DOI: 10.7554/elife.33854] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 06/10/2018] [Indexed: 11/22/2022] Open
Abstract
The brainstem’s lateral superior olive (LSO) is thought to be crucial for localizing high-frequency sounds by coding interaural sound level differences (ILD). Its neurons weigh contralateral inhibition against ipsilateral excitation, making their firing rate a function of the azimuthal position of a sound source. Since the very first in vivo recordings, LSO principal neurons have been reported to give sustained and temporally integrating ‘chopper’ responses to sustained sounds. Neurons with transient responses were observed but largely ignored and even considered a sign of pathology. Using the Mongolian gerbil as a model system, we have obtained the first in vivo patch clamp recordings from labeled LSO neurons and find that principal LSO neurons, the most numerous projection neurons of this nucleus, only respond at sound onset and show fast membrane features suggesting an importance for timing. These results provide a new framework to interpret previously puzzling features of this circuit.
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Affiliation(s)
- Tom P Franken
- Laboratory of Auditory Neurophysiology, KU Leuven, Leuven, Belgium
| | - Philip X Joris
- Laboratory of Auditory Neurophysiology, KU Leuven, Leuven, Belgium
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38
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Roberts MT. Out of balance: how a binaural coincidence detection circuit responds to unilateral deafferentation. J Physiol 2018; 596:1787-1788. [PMID: 29604080 DOI: 10.1113/jp276121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Michael T Roberts
- Kresge Hearing Research Institute and Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
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39
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Beiderbeck B, Myoga MH, Müller NIC, Callan AR, Friauf E, Grothe B, Pecka M. Precisely timed inhibition facilitates action potential firing for spatial coding in the auditory brainstem. Nat Commun 2018; 9:1771. [PMID: 29720589 PMCID: PMC5932051 DOI: 10.1038/s41467-018-04210-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 04/10/2018] [Indexed: 01/06/2023] Open
Abstract
The integration of excitatory and inhibitory synaptic inputs is fundamental to neuronal processing. In the mammalian auditory brainstem, neurons compare excitatory and inhibitory inputs from the ipsilateral and contralateral ear, respectively, for sound localization. However, the temporal precision and functional roles of inhibition in this integration process are unclear. Here, we demonstrate by in vivo recordings from the lateral superior olive (LSO) that inhibition controls spiking with microsecond precision throughout high frequency click trains. Depending on the relative timing of excitation and inhibition, neuronal spike probability is either suppressed or-unexpectedly-facilitated. In vitro conductance-clamp LSO recordings establish that a reduction in the voltage threshold for spike initiation due to a prior hyperpolarization results in post-inhibitory facilitation of otherwise sub-threshold synaptic events. Thus, microsecond-precise differences in the arrival of inhibition relative to excitation can facilitate spiking in the LSO, thereby promoting spatial sensitivity during the processing of faint sounds.
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Affiliation(s)
- Barbara Beiderbeck
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.,Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany
| | - Michael H Myoga
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.,Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried, 82152, Germany
| | - Nicolas I C Müller
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Kaiserslautern, D-67653, Germany
| | - Alexander R Callan
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.,Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany
| | - Eckhard Friauf
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Kaiserslautern, D-67653, Germany
| | - Benedikt Grothe
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany. .,Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried, 82152, Germany.
| | - Michael Pecka
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.
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40
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Lu Y, Liu Y, Curry RJ. Activity-dependent synaptic integration and modulation of bilateral excitatory inputs in an auditory coincidence detection circuit. J Physiol 2018; 596:1981-1997. [PMID: 29572827 DOI: 10.1113/jp275735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/05/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS Binaural excitatory inputs to coincidence detection neurons in nucleus laminaris (NL) play essential roles in interaural time difference coding for sound localization. Here, we show that the two excitatory inputs are physiologically nearly completely segregated. Synaptic integration shows linear summation of EPSPs, ensuring high efficiency of coincidence detection of the bilateral excitatory inputs. We further show that the two excitatory inputs to single NL neurons are symmetrical in synaptic strength, kinetics and short-term plasticity. Modulation of the EPSCs by metabotropic glutamate receptors (mGluRs) is identical between the two excitatory inputs, maintaining balanced bilateral excitation under neuromodulatory conditions. Unilateral hearing deprivation reduces synaptic excitation and paradoxically strengthens mGluR modulation of EPSCs, suggesting activity-dependent anti-homeostatic regulation, a novel synaptic plasticity in response to sensory manipulations. ABSTRACT Neurons in the avian nucleus laminaris (NL) receive bilateral excitatory inputs from the cochlear nucleus magnocellularis, via morphologically symmetrical dorsal (ipsilateral) and ventral (contralateral) dendrites. Using in vitro whole-cell patch recordings in chicken brainstem slices, we investigated synaptic integration and modulation of the bilateral inputs to NL under normal and hearing deprivation conditions. We found that the two excitatory inputs onto single NL neurons were nearly completely segregated, and integration of the two inputs was linear for EPSPs. The two inputs had similar synaptic strength, kinetics and short-term plasticity. EPSCs in low but not middle and high frequency neurons were suppressed by activation of group I and II metabotropic glutamate receptors (mGluR I and II), with similar modulatory strength between the ipsilateral and contralateral inputs. Unilateral hearing deprivation by cochlea removal reduced the excitatory transmission on the deprived dendritic domain of NL. Interestingly, EPSCs evoked at the deprived domain were modulated more strongly by mGluR II than at the counterpart domain that received intact input in low frequency neurons, suggesting anti-homeostatic regulation. This was supported by a stronger expression of mGluR II protein on the deprived neuropils of NL. Under mGluR II modulation, EPSCs on the deprived input show transient synaptic facilitation, forming a striking contrast with normal hearing conditions under which pure synaptic depression is observed. These results demonstrate physiological symmetry and thus balanced bilateral excitatory inputs to NL neurons. The activity-dependent anti-homeostatic plasticity of mGluR modulation constitutes a novel mechanism regulating synaptic transmission in response to sensory input manipulations.
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Affiliation(s)
- Yong Lu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
| | - Yuwei Liu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Rebecca J Curry
- Hearing Research Group, Department of Anatomy and Neurobiology, 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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41
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Winters BD, Golding NL. Glycinergic Inhibitory Plasticity in Binaural Neurons Is Cumulative and Gated by Developmental Changes in Action Potential Backpropagation. Neuron 2018; 98:166-178.e2. [PMID: 29576388 PMCID: PMC5886803 DOI: 10.1016/j.neuron.2018.03.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 01/09/2018] [Accepted: 02/28/2018] [Indexed: 11/20/2022]
Abstract
Utilization of timing-based sound localization cues by neurons in the medial superior olive (MSO) depends critically on glycinergic inhibitory inputs. After hearing onset, the strength and subcellular location of these inhibitory inputs are dramatically altered, but the cellular processes underlying this experience-dependent refinement are unknown. Here we reveal a form of inhibitory long-term potentiation (iLTP) in MSO neurons that is dependent on spiking and synaptic activation but is not affected by their fine-scale relative timing at higher frequencies prevalent in auditory circuits. We find that iLTP reinforces inhibitory inputs coactive with binaural excitation in a cumulative manner, likely well suited for networks featuring persistent high-frequency activity. We also show that a steep drop in action potential size and backpropagation limits induction of iLTP to the first 2 weeks of hearing. These intrinsic changes would deprive more distal inhibitory synapses of reinforcement, conceivably establishing the mature, soma-biased pattern of inhibition.
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Affiliation(s)
- Bradley D Winters
- The University of Texas at Austin, Department of Neuroscience and Center for Learning and Memory, 1 University Station C7000, Austin TX 78712-0248, USA
| | - Nace L Golding
- The University of Texas at Austin, Department of Neuroscience and Center for Learning and Memory, 1 University Station C7000, Austin TX 78712-0248, USA.
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42
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Encke J, Hemmert W. Extraction of Inter-Aural Time Differences Using a Spiking Neuron Network Model of the Medial Superior Olive. Front Neurosci 2018; 12:140. [PMID: 29559886 PMCID: PMC5845713 DOI: 10.3389/fnins.2018.00140] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/21/2018] [Indexed: 11/13/2022] Open
Abstract
The mammalian auditory system is able to extract temporal and spectral features from sound signals at the two ears. One important cue for localization of low-frequency sound sources in the horizontal plane are inter-aural time differences (ITDs) which are first analyzed in the medial superior olive (MSO) in the brainstem. Neural recordings of ITD tuning curves at various stages along the auditory pathway suggest that ITDs in the mammalian brainstem are not represented in form of a Jeffress-type place code. An alternative is the hemispheric opponent-channel code, according to which ITDs are encoded as the difference in the responses of the MSO nuclei in the two hemispheres. In this study, we present a physiologically-plausible, spiking neuron network model of the mammalian MSO circuit and apply two different methods of extracting ITDs from arbitrary sound signals. The network model is driven by a functional model of the auditory periphery and physiological models of the cochlear nucleus and the MSO. Using a linear opponent-channel decoder, we show that the network is able to detect changes in ITD with a precision down to 10 μs and that the sensitivity of the decoder depends on the slope of the ITD-rate functions. A second approach uses an artificial neuronal network to predict ITDs directly from the spiking output of the MSO and ANF model. Using this predictor, we show that the MSO-network is able to reliably encode static and time-dependent ITDs over a large frequency range, also for complex signals like speech.
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Affiliation(s)
- Jörg Encke
- Bioanaloge-Informationsverarbeitung, Department of Electrical and Computer Engineering, Technical University Munich, Munich, Germany
| | - Werner Hemmert
- Bioanaloge-Informationsverarbeitung, Department of Electrical and Computer Engineering, Technical University Munich, Munich, Germany
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Salminen NH, Jones SJ, Christianson GB, Marquardt T, McAlpine D. A common periodic representation of interaural time differences in mammalian cortex. Neuroimage 2018; 167:95-103. [PMID: 29122721 PMCID: PMC5854251 DOI: 10.1016/j.neuroimage.2017.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/01/2017] [Accepted: 11/04/2017] [Indexed: 11/16/2022] Open
Abstract
Binaural hearing, the ability to detect small differences in the timing and level of sounds at the two ears, underpins the ability to localize sound sources along the horizontal plane, and is important for decoding complex spatial listening environments into separate objects – a critical factor in ‘cocktail-party listening’. For human listeners, the most important spatial cue is the interaural time difference (ITD). Despite many decades of neurophysiological investigations of ITD sensitivity in small mammals, and computational models aimed at accounting for human perception, a lack of concordance between these studies has hampered our understanding of how the human brain represents and processes ITDs. Further, neural coding of spatial cues might depend on factors such as head-size or hearing range, which differ considerably between humans and commonly used experimental animals. Here, using magnetoencephalography (MEG) in human listeners, and electro-corticography (ECoG) recordings in guinea pig—a small mammal representative of a range of animals in which ITD coding has been assessed at the level of single-neuron recordings—we tested whether processing of ITDs in human auditory cortex accords with a frequency-dependent periodic code of ITD reported in small mammals, or whether alternative or additional processing stages implemented in psychoacoustic models of human binaural hearing must be assumed. Our data were well accounted for by a model consisting of periodically tuned ITD-detectors, and were highly consistent across the two species. The results suggest that the representation of ITD in human auditory cortex is similar to that found in other mammalian species, a representation in which neural responses to ITD are determined by phase differences relative to sound frequency rather than, for instance, the range of ITDs permitted by head size or the absolute magnitude or direction of ITD. ITD tuning is studied in human MEG and guinea pig ECoG with identical stimuli. Auditory cortical tuning to ITD is highly consistent across species. Results are consistent with a periodic, frequency-dependent code.
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Affiliation(s)
- Nelli H Salminen
- Brain and Mind Laboratory, Dept. of Neuroscience and Biomedical Engineering, MEG Core, Aalto NeuroImaging, Aalto University School of Science, Espoo, Finland.
| | - Simon J Jones
- UCL Ear Institute, 332 Gray's Inn Road, London, WC1X 8EE, UK
| | | | | | - David McAlpine
- UCL Ear Institute, 332 Gray's Inn Road, London, WC1X 8EE, UK; Dept of Linguistics, Australian Hearing Hub, Macquarie University, Sydney, NSW 2109, Australia
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Chambers AR, Pilati N, Balaram P, Large CH, Kaczmarek LK, Polley DB. Pharmacological modulation of Kv3.1 mitigates auditory midbrain temporal processing deficits following auditory nerve damage. Sci Rep 2017; 7:17496. [PMID: 29235497 PMCID: PMC5727503 DOI: 10.1038/s41598-017-17406-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/20/2017] [Indexed: 12/12/2022] Open
Abstract
Higher stages of central auditory processing compensate for a loss of cochlear nerve synapses by increasing the gain on remaining afferent inputs, thereby restoring firing rate codes for rudimentary sound features. The benefits of this compensatory plasticity are limited, as the recovery of precise temporal coding is comparatively modest. We reasoned that persistent temporal coding deficits could be ameliorated through modulation of voltage-gated potassium (Kv) channels that regulate temporal firing patterns. Here, we characterize AUT00063, a pharmacological compound that modulates Kv3.1, a high-threshold channel expressed in fast-spiking neurons throughout the central auditory pathway. Patch clamp recordings from auditory brainstem neurons and in silico modeling revealed that application of AUT00063 reduced action potential timing variability and improved temporal coding precision. Systemic injections of AUT00063 in vivo improved auditory synchronization and supported more accurate decoding of temporal sound features in the inferior colliculus and auditory cortex in adult mice with a near-complete loss of auditory nerve afferent synapses in the contralateral ear. These findings suggest modulating Kv3.1 in central neurons could be a promising therapeutic approach to mitigate temporal processing deficits that commonly accompany aging, tinnitus, ototoxic drug exposure or noise damage.
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Affiliation(s)
- Anna R Chambers
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA, USA.,Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Nadia Pilati
- Autifony SRL, Verona, Italy; and Autifony Therapeutics Limited, Imperial College Incubator, London, UK
| | - Pooja Balaram
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA, USA.,Department of Otolaryngology, Harvard Medical School, Boston, MA, USA
| | - Charles H Large
- Autifony SRL, Verona, Italy; and Autifony Therapeutics Limited, Imperial College Incubator, London, UK
| | - Leonard K Kaczmarek
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA, USA. .,Department of Otolaryngology, Harvard Medical School, Boston, MA, USA.
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Hambrook DA, Ilievski M, Mosadeghzad M, Tata M. A Bayesian computational basis for auditory selective attention using head rotation and the interaural time-difference cue. PLoS One 2017; 12:e0186104. [PMID: 28982139 PMCID: PMC5629026 DOI: 10.1371/journal.pone.0186104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 09/25/2017] [Indexed: 11/18/2022] Open
Abstract
The process of resolving mixtures of several sounds into their separate individual streams is known as auditory scene analysis and it remains a challenging task for computational systems. It is well-known that animals use binaural differences in arrival time and intensity at the two ears to find the arrival angle of sounds in the azimuthal plane, and this localization function has sometimes been considered sufficient to enable the un-mixing of complex scenes. However, the ability of such systems to resolve distinct sound sources in both space and frequency remains limited. The neural computations for detecting interaural time difference (ITD) have been well studied and have served as the inspiration for computational auditory scene analysis systems, however a crucial limitation of ITD models is that they produce ambiguous or "phantom" images in the scene. This has been thought to limit their usefulness at frequencies above about 1khz in humans. We present a simple Bayesian model and an implementation on a robot that uses ITD information recursively. The model makes use of head rotations to show that ITD information is sufficient to unambiguously resolve sound sources in both space and frequency. Contrary to commonly held assumptions about sound localization, we show that the ITD cue used with high-frequency sound can provide accurate and unambiguous localization and resolution of competing sounds. Our findings suggest that an "active hearing" approach could be useful in robotic systems that operate in natural, noisy settings. We also suggest that neurophysiological models of sound localization in animals could benefit from revision to include the influence of top-down memory and sensorimotor integration across head rotations.
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Affiliation(s)
- Dillon A. Hambrook
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Marko Ilievski
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Mohamad Mosadeghzad
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Matthew Tata
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
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Signatures of Somatic Inhibition and Dendritic Excitation in Auditory Brainstem Field Potentials. J Neurosci 2017; 37:10451-10467. [PMID: 28947575 DOI: 10.1523/jneurosci.0600-17.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 01/20/2023] Open
Abstract
Extracellular voltage recordings (Ve ; field potentials) provide an accessible view of in vivo neural activity, but proper interpretation of field potentials is a long-standing challenge. Computational modeling can aid in identifying neural generators of field potentials. In the auditory brainstem of cats, spatial patterns of sound-evoked Ve can resemble, strikingly, Ve generated by current dipoles. Previously, we developed a biophysically-based model of a binaural brainstem nucleus, the medial superior olive (MSO), that accounts qualitatively for observed dipole-like Ve patterns in sustained responses to monaural tones with frequencies >∼1000 Hz (Goldwyn et al., 2014). We have observed, however, that Ve patterns in cats of both sexes appear more monopole-like for lower-frequency tones. Here, we enhance our theory to accurately reproduce dipole and non-dipole features of Ve responses to monaural tones with frequencies ranging from 600 to 1800 Hz. By applying our model to data, we estimate time courses of paired input currents to MSO neurons. We interpret these inputs as dendrite-targeting excitation and soma-targeting inhibition (the latter contributes non-dipole-like features to Ve responses). Aspects of inferred inputs are consistent with synaptic inputs to MSO neurons including the tendencies of inhibitory inputs to attenuate in response to high-frequency tones and to precede excitatory inputs. Importantly, our updated theory can be tested experimentally by blocking synaptic inputs. MSO neurons perform a critical role in sound localization and binaural hearing. By solving an inverse problem to uncover synaptic inputs from Ve patterns we provide a new perspective on MSO physiology.SIGNIFICANCE STATEMENT Extracellular voltages (field potentials) are a common measure of brain activity. Ideally, one could infer from these data the activity of neurons and synapses that generate field potentials, but this "inverse problem" is not easily solved. We study brainstem field potentials in the region of the medial superior olive (MSO); a critical center in the auditory pathway. These field potentials exhibit distinctive spatial and temporal patterns in response to pure tone sounds. We use mathematical modeling in combination with physiological and anatomical knowledge of MSO neurons to plausibly explain how dendrite-targeting excitation and soma-targeting inhibition generate these field potentials. Inferring putative synaptic currents from field potentials advances our ability to study neural processing of sound in the MSO.
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Wei L, Karino S, Verschooten E, Joris PX. Enhancement of phase-locking in rodents. I. An axonal recording study in gerbil. J Neurophysiol 2017; 118:2009-2023. [PMID: 28701535 DOI: 10.1152/jn.00194.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 07/10/2017] [Accepted: 07/11/2017] [Indexed: 11/22/2022] Open
Abstract
The trapezoid body (TB) contains axons of neurons in the anteroventral cochlear nucleus projecting to monaural and binaural nuclei in the superior olivary complex (SOC). Characterization of these monaural inputs is important for the interpretation of response properties of SOC neurons. In particular, understanding of the sensitivity to interaural time differences (ITDs) in neurons of the medial and lateral superior olive requires knowledge of the temporal firing properties of the monaural excitatory and inhibitory inputs to these neurons. In recent years, studies of ITD sensitivity of SOC neurons have made increasing use of small animal models with good low-frequency hearing, particularly the gerbil. We presented stimuli as used in binaural studies to monaural neurons in the TB and studied their temporal coding. We found that general trends as have been described in the cat are present in gerbil, but with some important differences. Phase-locking to pure tones tends to be higher in TB axons and in neurons of the medial nucleus of the TB (MNTB) than in the auditory nerve for neurons with characteristic frequencies (CFs) below 1 kHz, but this enhancement is quantitatively more modest than in cat. Stronger enhancement is common when TB neurons are stimulated at low frequencies below CF. It is rare for TB neurons in gerbil to entrain to low-frequency stimuli, i.e., to discharge a well-timed spike on every stimulus cycle. Also, complex phase-locking behavior, with multiple modes of increased firing probability per stimulus cycle, is common in response to low frequencies below CF.NEW & NOTEWORTHY Phase-locking is an important property of neurons in the early auditory pathway: it is critical for the sensitivity to time differences between the two ears enabling spatial hearing. Studies in cat have shown an improvement in phase-locking from the peripheral to the central auditory nervous system. We recorded from axons in an output tract of the cochlear nucleus and show that a similar but more limited form of temporal enhancement is present in gerbil.
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Affiliation(s)
- Liting Wei
- Laboratory of Auditory Neurophysiology, KU Leuven, Leuven, Belgium
| | - Shotaro Karino
- 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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A Test of the Stereausis Hypothesis for Sound Localization in Mammals. J Neurosci 2017; 37:7278-7289. [PMID: 28659280 DOI: 10.1523/jneurosci.0233-17.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 05/20/2017] [Accepted: 05/25/2017] [Indexed: 11/21/2022] Open
Abstract
The relative arrival times of sounds at both ears constitute an important cue for localization of low-frequency sounds in the horizontal plane. The binaural neurons of the medial superior olive (MSO) act as coincidence detectors that fire when inputs from both ears arrive near simultaneously. Each principal neuron in the MSO is tuned to its own best interaural time difference (ITD), indicating the presence of an internal delay, a difference in the travel times from either ear to the MSO. According to the stereausis hypothesis, differences in wave propagation along the cochlea could provide the delays necessary for coincidence detection if the ipsilateral and contralateral inputs originated from different cochlear positions, with different frequency tuning. We therefore investigated the relation between interaural mismatches in frequency tuning and ITD tuning during in vivo loose-patch (juxtacellular) recordings from principal neurons of the MSO of anesthetized female gerbils. Cochlear delays can be bypassed by directly stimulating the auditory nerve; in agreement with the stereausis hypothesis, tuning for timing differences during bilateral electrical stimulation of the round windows differed markedly from ITD tuning in the same cells. Moreover, some neurons showed a frequency tuning mismatch that was sufficiently large to have a potential impact on ITD tuning. However, we did not find a correlation between frequency tuning mismatches and best ITDs. Our data thus suggest that axonal delays dominate ITD tuning.SIGNIFICANCE STATEMENT Neurons in the medial superior olive (MSO) play a unique role in sound localization because of their ability to compare the relative arrival time of low-frequency sounds at both ears. They fire maximally when the difference in sound arrival time exactly compensates for the internal delay: the difference in travel time from either ear to the MSO neuron. We tested whether differences in cochlear delay systematically contribute to the total travel time by comparing for individual MSO neurons the best difference in arrival times, as predicted from the frequency tuning for either ear, and the actual best difference. No systematic relation was observed, emphasizing the dominant contribution of axonal delays to the internal delay.
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Tolnai S, Beutelmann R, Klump GM. Exploring binaural hearing in gerbils (Meriones unguiculatus) using virtual headphones. PLoS One 2017; 12:e0175142. [PMID: 28394906 PMCID: PMC5386270 DOI: 10.1371/journal.pone.0175142] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/21/2017] [Indexed: 11/19/2022] Open
Abstract
The Mongolian gerbil (Meriones unguiculatus) has become a key species in investigations of the neural processing of sound localization cues in mammals. While its sound localization has been tested extensively under free-field stimulation, many neurophysiological studies use headphones to present signals with binaural localization cues. The gerbil's behavioral sensitivity to binaural cues, however, is unknown for the lack of appropriate stimulation paradigms in awake behaving gerbils. We close this gap in knowledge by mimicking a headphone stimulation; we use free-field loudspeakers and apply cross-talk cancellation techniques to present pure tones with binaural cues via “virtual headphones” to gerbils trained in a sound localization task. All gerbils were able to lateralize sounds depending on the interaural time or level difference (ITD and ILD, respectively). For ITD stimuli, reliable responses were seen for frequencies ≤2.9 kHz, the highest frequency tested with ITD stimuli. ITD sensitivity was frequency-dependent with the highest sensitivity observed at 1 kHz. For stimuli with ITD outside the gerbil's physiological range, responses were cyclic indicating the use of phase information when lateralizing narrow-band sounds. For ILD stimuli, reliable responses were obtained for frequencies ≥2 kHz. The comparison of ITD and ILD thresholds with ITD and ILD thresholds derived from gerbils’ free-field performance suggests that ongoing ITD information is the main cue for sound localization at frequencies <2 kHz. At 2 kHz, ITD and ILD cues are likely used in a complementary way. Verification of the use of the virtual headphones suggests that they can serve as a suitable substitute for conventional headphones particularly at frequencies ≤2 kHz.
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Affiliation(s)
- Sandra Tolnai
- Cluster of Excellence “Hearing4all”, Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
- * E-mail:
| | - Rainer Beutelmann
- Cluster of Excellence “Hearing4all”, Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Georg M. Klump
- Cluster of Excellence “Hearing4all”, Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
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Clinard CG, Hodgson SL, Scherer ME. Neural Correlates of the Binaural Masking Level Difference in Human Frequency-Following Responses. J Assoc Res Otolaryngol 2017; 18:355-369. [PMID: 27896486 PMCID: PMC5352611 DOI: 10.1007/s10162-016-0603-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 11/02/2016] [Indexed: 11/30/2022] Open
Abstract
The binaural masking level difference (BMLD) is an auditory phenomenon where binaural tone-in-noise detection is improved when the phase of either signal or noise is inverted in one of the ears (SπNo or SoNπ, respectively), relative to detection when signal and noise are in identical phase at each ear (SoNo). Processing related to BMLDs and interaural time differences has been confirmed in the auditory brainstem of non-human mammals; in the human auditory brainstem, phase-locked neural responses elicited by BMLD stimuli have not been systematically examined across signal-to-noise ratio. Behavioral and physiological testing was performed in three binaural stimulus conditions: SoNo, SπNo, and SoNπ. BMLDs at 500 Hz were obtained from 14 young, normal-hearing adults (ages 21-26). Physiological BMLDs used the frequency-following response (FFR), a scalp-recorded auditory evoked potential dependent on sustained phase-locked neural activity; FFR tone-in-noise detection thresholds were used to calculate physiological BMLDs. FFR BMLDs were significantly smaller (poorer) than behavioral BMLDs, and FFR BMLDs did not reflect a physiological release from masking, on average. Raw FFR amplitude showed substantial reductions in the SπNo condition relative to SoNo and SoNπ conditions, consistent with negative effects of phase summation from left and right ear FFRs. FFR amplitude differences between stimulus conditions (e.g., SoNo amplitude-SπNo amplitude) were significantly predictive of behavioral SπNo BMLDs; individuals with larger amplitude differences had larger (better) behavioral B MLDs and individuals with smaller amplitude differences had smaller (poorer) behavioral B MLDs. These data indicate a role for sustained phase-locked neural activity in BMLDs of humans and are the first to show predictive relationships between behavioral BMLDs and human brainstem responses.
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Affiliation(s)
- Christopher G. Clinard
- Department of Communication Sciences and Disorders, James Madison University, 235 Martin Luther King Jr. Way, MSC 4304, Harrisonburg, VA 22807 USA
| | - Sarah L. Hodgson
- Department of Communication Sciences and Disorders, James Madison University, 235 Martin Luther King Jr. Way, MSC 4304, Harrisonburg, VA 22807 USA
| | - Mary Ellen Scherer
- Department of Communication Sciences and Disorders, James Madison University, 235 Martin Luther King Jr. Way, MSC 4304, Harrisonburg, VA 22807 USA
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