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Barri A, Wiechert MT, Jazayeri M, DiGregorio DA. Synaptic basis of a sub-second representation of time in a neural circuit model. Nat Commun 2022; 13:7902. [PMID: 36550115 PMCID: PMC9780315 DOI: 10.1038/s41467-022-35395-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022] Open
Abstract
Temporal sequences of neural activity are essential for driving well-timed behaviors, but the underlying cellular and circuit mechanisms remain elusive. We leveraged the well-defined architecture of the cerebellum, a brain region known to support temporally precise actions, to explore theoretically whether the experimentally observed diversity of short-term synaptic plasticity (STP) at the input layer could generate neural dynamics sufficient for sub-second temporal learning. A cerebellar circuit model equipped with dynamic synapses produced a diverse set of transient granule cell firing patterns that provided a temporal basis set for learning precisely timed pauses in Purkinje cell activity during simulated delay eyelid conditioning and Bayesian interval estimation. The learning performance across time intervals was influenced by the temporal bandwidth of the temporal basis, which was determined by the input layer synaptic properties. The ubiquity of STP throughout the brain positions it as a general, tunable cellular mechanism for sculpting neural dynamics and fine-tuning behavior.
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Affiliation(s)
- A. Barri
- grid.508487.60000 0004 7885 7602Institut Pasteur, Université Paris Cité, Synapse and Circuit Dynamics Laboratory, CNRS UMR 3571 Paris, France
| | - M. T. Wiechert
- grid.508487.60000 0004 7885 7602Institut Pasteur, Université Paris Cité, Synapse and Circuit Dynamics Laboratory, CNRS UMR 3571 Paris, France
| | - M. Jazayeri
- grid.116068.80000 0001 2341 2786McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA USA ,grid.116068.80000 0001 2341 2786Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA USA
| | - D. A. DiGregorio
- grid.508487.60000 0004 7885 7602Institut Pasteur, Université Paris Cité, Synapse and Circuit Dynamics Laboratory, CNRS UMR 3571 Paris, France
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Tamás LT, Obrist D, Avan P, Büki B. Biasing the semicircular canal cupula in excitatory direction decreases the gain of the vestibuloocular reflex for head impulses. J Vestib Res 2020; 29:281-286. [DOI: 10.3233/ves-190681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- László T. Tamás
- Department of Otolaryngology, Petz Aladár Teaching Hospital, Györ, Hungary
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Paul Avan
- Laboratoire de Biophysique Neurosensorielle, Faculté de Médecine, Université Clermont Auvergne, Clermont Ferrand, Auvergne, France
| | - Béla Büki
- Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria
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Manca M, Glowatzki E, Roberts DC, Fridman GY, Aplin FP. Ionic direct current modulation evokes spike-rate adaptation in the vestibular periphery. Sci Rep 2019; 9:18924. [PMID: 31831760 PMCID: PMC6908704 DOI: 10.1038/s41598-019-55045-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/20/2019] [Indexed: 12/28/2022] Open
Abstract
Recent studies have shown that ionic direct current (iDC) can modulate the vestibular system in-vivo, with potential benefits over conventional pulsed stimulation. In this study, the effects of iDC stimulation on vestibular nerve fiber firing rate was investigated using loose-patch nerve fiber recordings in the acutely excised mouse crista ampullaris of the semicircular canals. Cathodic and anodic iDC steps instantaneously reduced and increased afferent spike rate, with the polarity of this effect dependent on the position of the stimulating electrode. A sustained constant anodic or cathodic current resulted in an adaptation to the stimulus and a return to spontaneous spike rate. Post-adaptation spike rate responses to iDC steps were similar to pre-adaptation controls. At high intensities spike rate response sensitivities were modified by the presence of an adaptation step. Benefits previously observed in behavioral responses to iDC steps delivered after sustained current may be due to post-adaptation changes in afferent sensitivity. These results contribute to an understanding of peripheral spike rate relationships for iDC vestibular stimulation and validate an ex-vivo model for future investigation of cellular mechanisms. In conjunction with previous in-vivo studies, these data help to characterize iDC stimulation as a potential therapy to restore vestibular function after bilateral vestibulopathy.
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Affiliation(s)
- Marco Manca
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States
| | - Elisabeth Glowatzki
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States.,Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland, 21205, United States
| | - Dale C Roberts
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States
| | - Gene Y Fridman
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States. .,Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, 21205, United States. .,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, 21205, United States.
| | - Felix P Aplin
- Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, 21205, United States
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Rabbitt RD. Semicircular canal biomechanics in health and disease. J Neurophysiol 2019; 121:732-755. [PMID: 30565972 PMCID: PMC6520623 DOI: 10.1152/jn.00708.2018] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.
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Affiliation(s)
- R. D. Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah
- Otolaryngology-Head Neck Surgery, University of Utah, Salt Lake City, Utah
- Neuroscience Program, University of Utah, Salt Lake City, Utah
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Abstract
OBJECTIVES During head rotations, neuronal firing rates increase in ipsilateral and decrease in contralateral vestibular afferents. At low accelerations, this "push-pull mechanism" is linear. At high accelerations, however, the change of firing rates is nonlinear in that the ipsilateral increase of firing rate is larger than the contralateral decrease. This mechanism of stronger ipsilateral excitation than contralateral inhibition during high-acceleration head rotation, known as Ewald's second law, is implemented within the nonlinear pathways. The authors asked whether caloric stimulation could provide an acceleration signal high enough to influence the contribution of the nonlinear pathway to the rotational vestibulo-ocular reflex gain (rVOR gain) during head impulses. DESIGN Caloric warm (44°C) and cold (24, 27, and 30°C) water irrigations of the left ear were performed in 7 healthy human subjects with the lateral semicircular canals oriented approximately earth-vertical (head inclined 30° from supine) and earth-horizontal (head inclined 30° from upright). RESULTS With the lateral semicircular canal oriented earth-vertical, the strongest cold caloric stimulus (24°C) significantly decreased the rVOR gain during ipsilateral head impulses, while all other irrigations, irrespective of head position, had no significant effect on rVOR gains during head impulses to either side. CONCLUSIONS Strong caloric irrigation, which can only be achieved with cold water, reduces the rVOR gain during ipsilateral head impulses and thus demonstrates Ewald's second law in healthy subjects. This unilateral gain reduction suggests that cold-water caloric irritation shifts the set point of the nonlinear relation between head acceleration and the vestibular firing rate toward a less acceleration-sensitive zone.
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Core Body Temperature Effects on the Mouse Vestibulo-ocular Reflex. J Assoc Res Otolaryngol 2017; 18:827-835. [PMID: 28755310 DOI: 10.1007/s10162-017-0639-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 07/17/2017] [Indexed: 01/12/2023] Open
Abstract
Core body temperature has been shown to affect vestibular end-organ and nerve afferents so that their resting discharge rate and sensitivity increase with temperature. Our aim was to determine whether these changes observed in extracellular nerve recordings of anaesthetized C57BL/6 mice corresponded to changes in the behavioural vestibulo-ocular reflex (VOR) of alert mice. The VOR drives eye rotations to keep images stable on the retina during head movements. We measured the VOR gain (eye velocity/head velocity) and phase (delay between vestibular stimulus and response) during whole-body sinusoidal rotations ranging 0.5-12 Hz with peak velocity 50 or 100 °/s in nine adult C57BL/6 mice. We also measured the VOR during whole-body transient rotations with acceleration 3000 or 6000 °/s2 reaching a plateau of 150 or 300 °/s. These measures were obtained while the mouse's core body temperature was held at either 32 or 37 °C for at least 35 min before recording. The temperature presentation order and timing were pseudo-randomized. We found that a temperature increase from 32 to 37 °C caused a significant increase in sinusoidal VOR gain of 17 % (P < 0.001). Temperature had no other effects on the behavioural VOR. Our data suggest that temperature effects on regularly firing afferents best correspond to the changes that we observed in the VOR gain.
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Iversen MM, Christensen DA, Parker DL, Holman HA, Chen J, Frerck MJ, Rabbitt RD. Low-intensity ultrasound activates vestibular otolith organs through acoustic radiation force. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:4209. [PMID: 28618821 PMCID: PMC5552392 DOI: 10.1121/1.4984287] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 05/11/2017] [Accepted: 05/15/2017] [Indexed: 06/03/2023]
Abstract
The present study examined the efficacy of 5 MHz low-intensity focused ultrasound (LiFU) as a stimulus to remotely activate inner ear vestibular otolith organs. The otolith organs are the primary sensory apparati responsible for detecting orientation of the head relative to gravity and linear acceleration in three-dimensional space. These organs also respond to loud sounds and vibration of the temporal bone. The oyster toadfish, Opsanus tau, was used to facilitate unobstructed acoustic access to the otolith organs in vivo. Single-unit responses to amplitude-modulated LiFU were recorded in afferent neurons identified as innervating the utricle or the saccule. Neural responses were equivalent to direct mechanical stimulation, and arose from the nonlinear acoustic radiation force acting on the otolithic mass. The magnitude of the acoustic radiation force acting on the otolith was measured ex vivo. Results demonstrate that LiFU stimuli can be tuned to mimic directional forces occurring naturally during physiological movements of the head, loud air conducted sound, or bone conducted vibration.
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Affiliation(s)
- M M Iversen
- Department of Bioengineering, University of Utah, 36 South Wasatch Drive, Salt Lake City, Utah 84112, USA
| | - D A Christensen
- Department of Bioengineering, University of Utah, 36 South Wasatch Drive, Salt Lake City, Utah 84112, USA
| | - D L Parker
- Department of Radiology, University of Utah, 30 North 1900 East, Salt Lake City, Utah 84132, USA
| | - H A Holman
- Department of Bioengineering, University of Utah, 36 South Wasatch Drive, Salt Lake City, Utah 84112, USA
| | - J Chen
- Communication Sciences and Disorders, University of Utah, 390 South 1530 East, Salt Lake City, Utah 84112, USA
| | - M J Frerck
- Department of Bioengineering, University of Utah, 36 South Wasatch Drive, Salt Lake City, Utah 84112, USA
| | - R D Rabbitt
- Department of Bioengineering, University of Utah, 36 South Wasatch Drive, Salt Lake City, Utah 84112, USA
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Rabbitt RD, Brichta AM, Tabatabaee H, Boutros PJ, Ahn J, Della Santina CC, Poppi LA, Lim R. Heat pulse excitability of vestibular hair cells and afferent neurons. J Neurophysiol 2016; 116:825-43. [PMID: 27226448 DOI: 10.1152/jn.00110.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 05/24/2016] [Indexed: 11/22/2022] Open
Abstract
In the present study we combined electrophysiology with optical heat pulse stimuli to examine thermodynamics of membrane electrical excitability in mammalian vestibular hair cells and afferent neurons. We recorded whole cell currents in mammalian type II vestibular hair cells using an excised preparation (mouse) and action potentials (APs) in afferent neurons in vivo (chinchilla) in response to optical heat pulses applied to the crista (ΔT ≈ 0.25°C per pulse). Afferent spike trains evoked by heat pulse stimuli were diverse and included asynchronous inhibition, asynchronous excitation, and/or phase-locked APs synchronized to each infrared heat pulse. Thermal responses of membrane currents responsible for APs in ganglion neurons were strictly excitatory, with Q10 ≈ 2. In contrast, hair cells responded with a mix of excitatory and inhibitory currents. Excitatory hair cell membrane currents included a thermoelectric capacitive current proportional to the rate of temperature rise (dT/dt) and an inward conduction current driven by ΔT An iberiotoxin-sensitive inhibitory conduction current was also evoked by ΔT, rising in <3 ms and decaying with a time constant of ∼24 ms. The inhibitory component dominated whole cell currents in 50% of hair cells at -68 mV and in 67% of hair cells at -60 mV. Responses were quantified and described on the basis of first principles of thermodynamics. Results identify key molecular targets underlying heat pulse excitability in vestibular sensory organs and provide quantitative methods for rational application of optical heat pulses to examine protein biophysics and manipulate cellular excitability.
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Affiliation(s)
- Richard D Rabbitt
- Departments of Bioengineering and Otolaryngology, University of Utah, Salt Lake City, Utah;
| | - Alan M Brichta
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia; and
| | - Hessam Tabatabaee
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia; and
| | - Peter J Boutros
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - JoongHo Ahn
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Charles C Della Santina
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Lauren A Poppi
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia; and
| | - Rebecca Lim
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia; and
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Synaptic diversity enables temporal coding of coincident multisensory inputs in single neurons. Nat Neurosci 2015; 18:718-27. [PMID: 25821914 PMCID: PMC4413433 DOI: 10.1038/nn.3974] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/12/2015] [Indexed: 02/08/2023]
Abstract
The ability of the brain to rapidly process information from multiple pathways is critical for reliable execution of complex sensory-motor behaviors, yet the cellular mechanisms underlying a neuronal representation of multimodal stimuli are poorly understood. Here we explored the possibility that the physiological diversity of mossy fiber (MF) to granule cell (GC) synapses within the mouse vestibulocerebellum may contribute to the processing of coincident multisensory information at the level of individual GCs. We found that the strength and short-term dynamics of individual MF-GC synapses can act as biophysical signatures for primary vestibular, secondary vestibular and visual input pathways. The majority of GCs receive inputs from different modalities, which when co-activated, produced enhanced GC firing rates and distinct first spike latencies. Thus, pathway-specific synaptic response properties permit temporal coding of correlated multisensory input by single GCs, thereby enriching sensory representation and facilitating pattern separation.
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Kim KS, Minor LB, Della Santina CC, Lasker DM. Variation in response dynamics of regular and irregular vestibular-nerve afferents during sinusoidal head rotations and currents in the chinchilla. Exp Brain Res 2011; 210:643-9. [PMID: 21369854 DOI: 10.1007/s00221-011-2600-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 02/08/2011] [Indexed: 01/09/2023]
Abstract
In mammals, vestibular-nerve afferents that innervate only type I hair cells (calyx-only afferents) respond nearly in phase with head acceleration for high-frequency motion, whereas afferents that innervate both type I and type II (dimorphic) or only type II (bouton-only) hair cells respond more in phase with head velocity. Afferents that exhibit irregular background discharge rates have a larger phase lead re-head velocity than those that fire more regularly. The goal of this study was to investigate the cause of the variation in phase lead between regular and irregular afferents at high-frequency head rotations. Under the assumption that externally applied galvanic currents act directly on the nerve, we derived a transfer function describing the dynamics of a semicircular canal and its hair cells through comparison of responses to sinusoidally modulated head velocity and currents. Responses of all afferents were fit well with a transfer function with one zero (lead term). Best-fit lead terms describing responses to current for each group of afferents were similar to the lead term describing responses to head velocity for regular afferents (0.006 s + 1). This finding indicated that the pre-synaptic and synaptic inputs to regular afferents were likely to be pure velocity transducers. However, the variation in phase lead between regular and irregular afferents could not be explained solely by the ratio of type I to II hair cells (Baird et al 1988), suggesting that the variation was caused by a combination of pre- (type of hair cell) and post-synaptic properties.
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Affiliation(s)
- Kyu-Sung Kim
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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