1
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Kwon J, Lee S, Jo Y, Choi M. All-optical observation on activity-dependent nanoscale dynamics of myelinated axons. NEUROPHOTONICS 2023; 10:015003. [PMID: 36699624 PMCID: PMC9868287 DOI: 10.1117/1.nph.10.1.015003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
SIGNIFICANCE In the mammalian brain, rapid conduction of neural information is supported by the myelin, the functional efficacy of which shows steep dependence on its nanoscale cytoarchitecture. Although previous in vitro studies have suggested that neural activity accompanies nanometer-scale cellular deformations, whether neural activity can dynamically remodel the myelinated axon has remained unexplored due to the technical challenge in observing its nanostructural dynamics in living tissues. AIM We aim to observe activity-dependent nanostructural dynamics of myelinated axons in a living brain tissue. APPROACH We introduced a novel all-optical approach combining a nanoscale dynamic readout based on spectral interferometry and optogenetic control of neural excitation in an acute brain slice preparation. RESULTS In response to optogenetically evoked neuronal burst firing, the myelinated axons exhibited progressive and reversible spectral redshifts, corresponding to the transient swelling at a subnanometer scale. We further revealed that the activity-dependent nanostructural dynamics was localized to the paranode. CONCLUSIONS Our all-optical studies substantiate that myelinated axon exhibits activity-dependent nanoscale swelling, which potentially serves to dynamically tune the transmission speed of neural information.
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Affiliation(s)
- Junhwan Kwon
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
| | - Sungho Lee
- Seoul National University, School of Biological Sciences, Seoul, Republic of Korea
- Seoul National University, The Institute of Molecular Biology and Genetics, Seoul, Republic of Korea
| | - Yongjae Jo
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
| | - Myunghwan Choi
- Seoul National University, School of Biological Sciences, Seoul, Republic of Korea
- Seoul National University, The Institute of Molecular Biology and Genetics, Seoul, Republic of Korea
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2
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Rabbitt RD. Analysis of outer hair cell electromechanics reveals power delivery at the upper-frequency limits of hearing. J R Soc Interface 2022; 19:20220139. [PMID: 35673856 PMCID: PMC9174718 DOI: 10.1098/rsif.2022.0139] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/11/2022] [Indexed: 11/12/2022] Open
Abstract
Outer hair cells are the cellular motors in the mammalian inner ear responsible for sensitive high-frequency hearing. Motor function over the frequency range of human hearing requires expression of the protein prestin in the OHC lateral membrane, which imparts piezoelectric properties to the cell membrane. In the present report, electrical power consumption and mechanical power output of the OHC membrane-motor complex are determined using previously published voltage-clamp data from isolated OHCs and membrane patches. Results reveal that power output peaks at a best frequency much higher than implied by the low-pass character of nonlinear capacitance, and much higher than the whole-cell resistive-capacitive corner frequency. High frequency power output is enabled by a -90° shift in the phase of electrical charge displacement in the membrane, manifested electrically as emergence of imaginary-valued nonlinear capacitance.
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Affiliation(s)
- Richard D. Rabbitt
- Biomedical Engineering, Otolaryngology, and Neuroscience Program, University of Utah, 36 S. Wasatch Drive, SMBB 3100, Salt Lake City, UT 84112, USA
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3
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Iyer RR, Liu YZ, Renteria CA, Tibble BE, Choi H, Žurauskas M, Boppart SA. Ultra-parallel label-free optophysiology of neural activity. iScience 2022; 25:104307. [PMID: 35602935 PMCID: PMC9114528 DOI: 10.1016/j.isci.2022.104307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 02/18/2022] [Accepted: 04/22/2022] [Indexed: 01/21/2023] Open
Abstract
The electrical activity of neurons has a spatiotemporal footprint that spans three orders of magnitude. Traditional electrophysiology lacks the spatial throughput to image the activity of an entire neural network; besides, labeled optical imaging using voltage-sensitive dyes and tracking Ca2+ ion dynamics lack the versatility and speed to capture fast-spiking activity, respectively. We present a label-free optical imaging technique to image the changes to the optical path length and the local birefringence caused by neural activity, at 4,000 Hz, across a 200 × 200 μm2 region, and with micron-scale spatial resolution and 300-pm displacement sensitivity using Superfast Polarization-sensitive Off-axis Full-field Optical Coherence Microscopy (SPoOF OCM). The undulations in the optical responses from mammalian neuronal activity were matched with field-potential electrophysiology measurements and validated with channel blockers. By directly tracking the widefield neural activity at millisecond timescales and micrometer resolution, SPoOF OCM provides a framework to progress from low-throughput electrophysiology to high-throughput ultra-parallel label-free optophysiology.
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Affiliation(s)
- Rishyashring R. Iyer
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Yuan-Zhi Liu
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Carlos A. Renteria
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Brian E. Tibble
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Honggu Choi
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Mantas Žurauskas
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Stephen A. Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, IL, USA,Corresponding author
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4
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Galassi VV, Wilke N. On the Coupling between Mechanical Properties and Electrostatics in Biological Membranes. MEMBRANES 2021; 11:478. [PMID: 34203412 PMCID: PMC8306103 DOI: 10.3390/membranes11070478] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/18/2021] [Accepted: 06/22/2021] [Indexed: 12/24/2022]
Abstract
Cell membrane structure is proposed as a lipid matrix with embedded proteins, and thus, their emerging mechanical and electrostatic properties are commanded by lipid behavior and their interconnection with the included and absorbed proteins, cytoskeleton, extracellular matrix and ionic media. Structures formed by lipids are soft, dynamic and viscoelastic, and their properties depend on the lipid composition and on the general conditions, such as temperature, pH, ionic strength and electrostatic potentials. The dielectric constant of the apolar region of the lipid bilayer contrasts with that of the polar region, which also differs from the aqueous milieu, and these changes happen in the nanometer scale. Besides, an important percentage of the lipids are anionic, and the rest are dipoles or higher multipoles, and the polar regions are highly hydrated, with these water molecules forming an active part of the membrane. Therefore, electric fields (both, internal and external) affects membrane thickness, density, tension and curvature, and conversely, mechanical deformations modify membrane electrostatics. As a consequence, interfacial electrostatics appears as a highly important parameter, affecting the membrane properties in general and mechanical features in particular. In this review we focus on the electromechanical behavior of lipid and cell membranes, the physicochemical origin and the biological implications, with emphasis in signal propagation in nerve cells.
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Affiliation(s)
- Vanesa Viviana Galassi
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza M5500, Argentina;
- Instituto Interdisciplinario de Ciencias Básicas (ICB), Universidad Nacional de Cuyo, CONICET, Mendoza M5500, Argentina
| | - Natalia Wilke
- Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Universidad Nacional de Córdoba, CONICET, Córdoba X5000HUA, Argentina
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5
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Pandiyan VP, Maloney-Bertelli A, Kuchenbecker JA, Boyle KC, Ling T, Chen ZC, Park BH, Roorda A, Palanker D, Sabesan R. The optoretinogram reveals the primary steps of phototransduction in the living human eye. SCIENCE ADVANCES 2020; 6:6/37/eabc1124. [PMID: 32917686 PMCID: PMC9222118 DOI: 10.1126/sciadv.abc1124] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/24/2020] [Indexed: 05/05/2023]
Abstract
Photoreceptors initiate vision by converting photons to electrical activity. The onset of the phototransduction cascade is marked by the isomerization of photopigments upon light capture. We revealed that the onset of phototransduction is accompanied by a rapid (<5 ms), nanometer-scale electromechanical deformation in individual human cone photoreceptors. Characterizing this biophysical phenomenon associated with phototransduction in vivo was enabled by high-speed phase-resolved optical coherence tomography in a line-field configuration that allowed sufficient spatiotemporal resolution to visualize the nanometer/millisecond-scale light-induced shape change in photoreceptors. The deformation was explained as the optical manifestation of electrical activity, caused due to rapid charge displacement following isomerization, resulting in changes of electrical potential and surface tension within the photoreceptor disc membranes. These all-optical recordings of light-induced activity in the human retina constitute an optoretinogram and hold remarkable potential to reveal the biophysical correlates of neural activity in health and disease.
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Affiliation(s)
| | | | | | - Kevin C Boyle
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Tong Ling
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Zhijie Charles Chen
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - B Hyle Park
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Austin Roorda
- School of Optometry, University of California, Berkeley, CA 94720, USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA.
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6
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Ling T, Boyle KC, Zuckerman V, Flores T, Ramakrishnan C, Deisseroth K, Palanker D. High-speed interferometric imaging reveals dynamics of neuronal deformation during the action potential. Proc Natl Acad Sci U S A 2020; 117:10278-10285. [PMID: 32341158 PMCID: PMC7229674 DOI: 10.1073/pnas.1920039117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neurons undergo nanometer-scale deformations during action potentials, and the underlying mechanism has been actively debated for decades. Previous observations were limited to a single spot or the cell boundary, while movement across the entire neuron during the action potential remained unclear. Here we report full-field imaging of cellular deformations accompanying the action potential in mammalian neuron somas (-1.8 to 1.4 nm) and neurites (-0.7 to 0.9 nm), using high-speed quantitative phase imaging with a temporal resolution of 0.1 ms and an optical path length sensitivity of <4 pm per pixel. The spike-triggered average, synchronized to electrical recording, demonstrates that the time course of the optical phase changes closely matches the dynamics of the electrical signal. Utilizing the spatial and temporal correlations of the phase signals across the cell, we enhance the detection and segmentation of spiking cells compared to the shot-noise-limited performance of single pixels. Using three-dimensional (3D) cellular morphology extracted via confocal microscopy, we demonstrate that the voltage-dependent changes in the membrane tension induced by ionic repulsion can explain the magnitude, time course, and spatial features of the phase imaging. Our full-field observations of the spike-induced deformations shed light upon the electromechanical coupling mechanism in electrogenic cells and open the door to noninvasive label-free imaging of neural signaling.
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Affiliation(s)
- Tong Ling
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305;
- Department of Ophthalmology, Stanford University, Stanford, CA 94305
| | - Kevin C Boyle
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305;
| | - Valentina Zuckerman
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305
| | - Thomas Flores
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305
| | | | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305;
- Department of Ophthalmology, Stanford University, Stanford, CA 94305
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7
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Tang P, Li Y, Rakymzhan A, Xie Z, Wang RK. Measurement and visualization of stimulus-evoked tissue dynamics in mouse barrel cortex using phase-sensitive optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2020; 11:699-710. [PMID: 32206393 PMCID: PMC7041479 DOI: 10.1364/boe.381332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/04/2019] [Accepted: 01/02/2020] [Indexed: 05/24/2023]
Abstract
We describe a method to measure tissue dynamics in mouse barrel cortex during functional activation via phase-sensitive optical coherence tomography (PhS-OCT). The method measures the phase changes in OCT signals, which are induced by the tissue volume change, upon which to localize the activated tissue region. Phase unwrapping, compensation and normalization are applied to increase the dynamic range of the OCT phase detection. To guide the OCT scanning, intrinsic optical signal imaging (IOSI) system equipped with a green light laser source (532 nm) is integrated with the PhS-OCT system to provide a full field time-lapsed images of the reflectance that is used to identify the transversal 2D localized tissue response in the mouse brain. The OCT results show a localized decrease in the OCT phase signal in the activated region of the mouse brain tissue. The decrease in the phase signal may be originated from the brain tissue compression caused by the vasodilatation in the activated region. The activated region revealed in the cross-sectional OCT image is consistent with that identified by the IOSI imaging, indicating the phase change in the OCT signals may associate with the changes in the corresponding hemodynamics. In vivo localized tissue dynamics in the barrel cortex at depth during whisker stimulation is observed and monitored in this study.
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8
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Jerusalem A, Al-Rekabi Z, Chen H, Ercole A, Malboubi M, Tamayo-Elizalde M, Verhagen L, Contera S. Electrophysiological-mechanical coupling in the neuronal membrane and its role in ultrasound neuromodulation and general anaesthesia. Acta Biomater 2019; 97:116-140. [PMID: 31357005 DOI: 10.1016/j.actbio.2019.07.041] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 07/20/2019] [Accepted: 07/23/2019] [Indexed: 01/23/2023]
Abstract
The current understanding of the role of the cell membrane is in a state of flux. Recent experiments show that conventional models, considering only electrophysiological properties of a passive membrane, are incomplete. The neuronal membrane is an active structure with mechanical properties that modulate electrophysiology. Protein transport, lipid bilayer phase, membrane pressure and stiffness can all influence membrane capacitance and action potential propagation. A mounting body of evidence indicates that neuronal mechanics and electrophysiology are coupled, and together shape the membrane potential in tight coordination with other physical properties. In this review, we summarise recent updates concerning electrophysiological-mechanical coupling in neuronal function. In particular, we aim at making the link with two relevant yet often disconnected fields with strong clinical potential: the use of mechanical vibrations-ultrasound-to alter the electrophysiogical state of neurons, e.g., in neuromodulation, and the theories attempting to explain the action of general anaesthetics. STATEMENT OF SIGNIFICANCE: General anaesthetics revolutionised medical practice; now an apparently unrelated technique, ultrasound neuromodulation-aimed at controlling neuronal activity by means of ultrasound-is poised to achieve a similar level of impact. While both technologies are known to alter the electrophysiology of neurons, the way they achieve it is still largely unknown. In this review, we argue that in order to explain their mechanisms/effects, the neuronal membrane must be considered as a coupled mechano-electrophysiological system that consists of multiple physical processes occurring concurrently and collaboratively, as opposed to sequentially and independently. In this framework the behaviour of the cell membrane is not the result of stereotypical mechanisms in isolation but instead emerges from the integrative behaviour of a complexly coupled multiphysics system.
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Affiliation(s)
- Antoine Jerusalem
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
| | - Zeinab Al-Rekabi
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Haoyu Chen
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Ari Ercole
- Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Majid Malboubi
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Miren Tamayo-Elizalde
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Lennart Verhagen
- Wellcome Centre for Integrative Neuroimaging (WIN), Department of Experimental Psychology, University of Oxford, Oxford OX1 3TA, UK; WIN, Centre for Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Sonia Contera
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
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9
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Chen H, Garcia-Gonzalez D, Jérusalem A. Computational model of the mechanoelectrophysiological coupling in axons with application to neuromodulation. Phys Rev E 2019; 99:032406. [PMID: 30999419 DOI: 10.1103/physreve.99.032406] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Indexed: 02/06/2023]
Abstract
For more than half a century, the action potential (AP) has been considered a purely electrical phenomenon. However, experimental observations of membrane deformations occurring during APs have revealed that this process also involves mechanical features. This discovery has recently fuelled a controversy on the real nature of APs: whether they are mechanical or electrical. In order to examine some of the modern hypotheses regarding APs, we propose here a coupled mechanoelectrophysiological membrane finite-element model for neuronal axons. The axon is modeled as an axisymmetric thin-wall cylindrical tube. The electrophysiology of the membrane is modeled using the classic Hodgkin-Huxley (H-H) equations for the Nodes of Ranvier or unmyelinated axons and the cable theory for the internodal regions, whereas the axonal mechanics is modeled by means of viscoelasticity theory. Membrane potential changes induce a strain gradient field via reverse flexoelectricity, whereas mechanical pulses result in an electrical self-polarization field following the direct flexoelectric effect, in turn influencing the membrane potential. Moreover, membrane deformation also alters the values of membrane capacitance and resistance in the H-H equation. These three effects serve as the fundamental coupling mechanisms between the APs and mechanical pulses in the model. A series of numerical studies was systematically conducted to investigate the consequences of interaction between the APs and mechanical waves on both myelinated and unmyelinated axons. Simulation results illustrate that the AP is always accompanied by an in-phase propagating membrane displacement of ≈1nm, whereas mechanical pulses with enough magnitude can also trigger APs. The model demonstrates that mechanical vibrations, such as the ones arising from ultrasound stimulations, can either annihilate or enhance axonal electrophysiology depending on their respective directionality and frequency. It also shows that frequency of pulse repetition can also enhance signal propagation independently of the amplitude of the signal. This result not only reconciles the mechanical and electrical natures of the APs but also provides an explanation for the experimentally observed mechanoelectrophysiological phenomena in axons, especially in the context of ultrasound neuromodulation.
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Affiliation(s)
- Haoyu Chen
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, United Kingdom
| | | | - Antoine Jérusalem
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, United Kingdom
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10
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Troiani F, Nikolic K, Constandinou TG. Simulating optical coherence tomography for observing nerve activity: A finite difference time domain bi-dimensional model. PLoS One 2018; 13:e0200392. [PMID: 29990346 PMCID: PMC6039043 DOI: 10.1371/journal.pone.0200392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 06/24/2018] [Indexed: 11/19/2022] Open
Abstract
We present a finite difference time domain (FDTD) model for computation of A line scans in time domain optical coherence tomography (OCT). The OCT output signal is created using two different simulations for the reference and sample arms, with a successive computation of the interference signal with external software. In this paper we present the model applied to two different samples: a glass rod filled with water-sucrose solution at different concentrations and a peripheral nerve. This work aims to understand to what extent time domain OCT can be used for non-invasive, direct optical monitoring of peripheral nerve activity.
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Affiliation(s)
- Francesca Troiani
- Centre for Bio-Inspired Technology, Imperial College London, London, United Kingdom
| | - Konstantin Nikolic
- Centre for Bio-Inspired Technology, Imperial College London, London, United Kingdom
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11
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Ling T, Boyle KC, Goetz G, Zhou P, Quan Y, Alfonso FS, Huang TW, Palanker D. Full-field interferometric imaging of propagating action potentials. LIGHT, SCIENCE & APPLICATIONS 2018; 7:107. [PMID: 30564313 PMCID: PMC6290013 DOI: 10.1038/s41377-018-0107-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/24/2018] [Accepted: 11/24/2018] [Indexed: 05/15/2023]
Abstract
Currently, cellular action potentials are detected using either electrical recordings or exogenous fluorescent probes that sense the calcium concentration or transmembrane voltage. Ca imaging has a low temporal resolution, while voltage indicators are vulnerable to phototoxicity, photobleaching, and heating. Here, we report full-field interferometric imaging of individual action potentials by detecting movement across the entire cell membrane. Using spike-triggered averaging of movies synchronized with electrical recordings, we demonstrate deformations up to 3 nm (0.9 mrad) during the action potential in spiking HEK-293 cells, with a rise time of 4 ms. The time course of the optically recorded spikes matches the electrical waveforms. Since the shot noise limit of the camera (~2 mrad/pix) precludes detection of the action potential in a single frame, for all-optical spike detection, images are acquired at 50 kHz, and 50 frames are binned into 1 ms steps to achieve a sensitivity of 0.3 mrad in a single pixel. Using a self-reinforcing sensitivity enhancement algorithm based on iteratively expanding the region of interest for spatial averaging, individual spikes can be detected by matching the previously extracted template of the action potential with the optical recording. This allows all-optical full-field imaging of the propagating action potentials without exogeneous labels or electrodes.
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Affiliation(s)
- Tong Ling
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305 USA
| | - Kevin C. Boyle
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Georges Goetz
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 USA
| | - Peng Zhou
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305 USA
| | - Yi Quan
- Department of Ophthalmology, Stanford University, Stanford, CA 94305 USA
| | - Felix S. Alfonso
- Department of Chemistry, Stanford University, Stanford, CA 94305 USA
| | - Tiffany W. Huang
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305 USA
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12
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Batabyal S, Satpathy S, Bui L, Kim YT, Mohanty S, Bachoo R, Davé DP. Label-free optical detection of action potential in mammalian neurons. BIOMEDICAL OPTICS EXPRESS 2017; 8:3700-3713. [PMID: 28856044 PMCID: PMC5560835 DOI: 10.1364/boe.8.003700] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 05/08/2023]
Abstract
We describe an optical technique for label-free detection of the action potential in cultured mammalian neurons. Induced morphological changes due to action potential propagation in neurons are optically interrogated with a phase sensitive interferometric technique. Optical recordings composed of signal pulses mirror the electrical spike train activity of individual neurons in a network. The optical pulses are transient nanoscale oscillatory changes in the optical path length of varying peak magnitude and temporal width. Exogenous application of glutamate to cortical neuronal cultures produced coincident increase in the electrical and optical activity; both were blocked by application of a Na-channel blocker, Tetrodotoxin. The observed transient change in optical path length in a single optical pulse is primarily due to physical fluctuations of the neuronal cell membrane mediated by a yet unknown electromechanical transduction phenomenon. Our analysis suggests a traveling surface wave in the neuronal cell membrane is responsible for the measured optical signal pulses.
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Affiliation(s)
- Subrata Batabyal
- Nanoscope Technologies, Arlington, TX, USA
- Nanoscope Technologies, Arlington, TX, USA
- Equal Contribution
| | - Sarmishtha Satpathy
- Department of Electrical Engineering, University of Texas at Arlington, TX, USA
- Equal Contribution
| | - Loan Bui
- Department of Bioengineering, University of Texas at Arlington, TX, USA
| | - Young-Tae Kim
- Department of Bioengineering, University of Texas at Arlington, TX, USA
| | | | - Robert Bachoo
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Digant P Davé
- Department of Bioengineering, University of Texas at Arlington, TX, USA
- Advance Imaging Research Centre, University of Texas Southwestern Medical Center, Dallas, TX, USA
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13
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Tong MQ, Hasan MM, Lee SS, Haque MR, Kim DH, Islam MS, Adams ME, Park BH. OCT intensity and phase fluctuations correlated with activity-dependent neuronal calcium dynamics in the Drosophila CNS [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:726-735. [PMID: 28270979 PMCID: PMC5330578 DOI: 10.1364/boe.8.000726] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/04/2017] [Accepted: 01/06/2017] [Indexed: 05/09/2023]
Abstract
Phase-resolved OCT and fluorescence microscopy were used simultaneously to examine stereotypic patterns of neural activity in the isolated Drosophila central nervous system. Both imaging modalities were focused on individually identified bursicon neurons known to be involved in a fixed action pattern initiated by ecdysis-triggering hormone. We observed clear correspondence of OCT intensity, phase fluctuations, and activity-dependent calcium-induced fluorescence.
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Affiliation(s)
- Minh Q. Tong
- Graduate Program in Neuroscience, University of California, Riverside, CA 92521, USA
| | - Md. Monirul Hasan
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - Sang Soo Lee
- Graduate Program in Neuroscience, University of California, Riverside, CA 92521, USA
| | - Md. Rezuanul Haque
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - Do-Hyoung Kim
- Department of Entomology, University of California, 900 University Ave, Riverside, CA 92521, USA
- Current Affiliation Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea
| | - Md. Shahidul Islam
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - Michael E. Adams
- Graduate Program in Neuroscience, University of California, Riverside, CA 92521, USA
- Department of Entomology, University of California, 900 University Ave, Riverside, CA 92521, USA
- Department of Cell Biology & Neuroscience, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - B. Hyle Park
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
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14
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Men J, Huang Y, Solanki J, Zeng X, Alex A, Jerwick J, Zhang Z, Tanzi RE, Li A, Zhou C. Optical Coherence Tomography for Brain Imaging and Developmental Biology. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS : A PUBLICATION OF THE IEEE LASERS AND ELECTRO-OPTICS SOCIETY 2016; 22:6803213. [PMID: 27721647 PMCID: PMC5049888 DOI: 10.1109/jstqe.2015.2513667] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography (OCT) is a promising research tool for brain imaging and developmental biology. Serving as a three-dimensional optical biopsy technique, OCT provides volumetric reconstruction of brain tissues and embryonic structures with micrometer resolution and video rate imaging speed. Functional OCT enables label-free monitoring of hemodynamic and metabolic changes in the brain in vitro and in vivo in animal models. Due to its non-invasiveness nature, OCT enables longitudinal imaging of developing specimens in vivo without potential damage from surgical operation, tissue fixation and processing, and staining with exogenous contrast agents. In this paper, various OCT applications in brain imaging and developmental biology are reviewed, with a particular focus on imaging heart development. In addition, we report findings on the effects of a circadian gene (Clock) and high-fat-diet on heart development in Drosophila melanogaster. These findings contribute to our understanding of the fundamental mechanisms connecting circadian genes and obesity to heart development and cardiac diseases.
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Affiliation(s)
- Jing Men
- Department of Electrical and Computer Engineering, Center for Photonics and Nanoelectronics, and Bioengineering Program, Lehigh University, Bethlehem, PA, USA, 18015
| | - Yongyang Huang
- Department of Electrical and Computer Engineering, Center for Photonics and Nanoelectronics, and Bioengineering Program, Lehigh University, Bethlehem, PA, USA, 18015
| | - Jitendra Solanki
- Department of Electrical and Computer Engineering, Center for Photonics and Nanoelectronics, and Bioengineering Program, Lehigh University, Bethlehem, PA, USA, 18015
| | - Xianxu Zeng
- Department of Electrical and Computer Engineering, Center for Photonics and Nanoelectronics, and Bioengineering Program, Lehigh University, Bethlehem, PA, USA, 18015
- Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China, 450000
| | - Aneesh Alex
- Department of Electrical and Computer Engineering, Center for Photonics and Nanoelectronics, and Bioengineering Program, Lehigh University, Bethlehem, PA, USA, 18015
| | - Jason Jerwick
- Department of Electrical and Computer Engineering, Center for Photonics and Nanoelectronics, and Bioengineering Program, Lehigh University, Bethlehem, PA, USA, 18015
| | - Zhan Zhang
- Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China, 450000
| | - Rudolph E. Tanzi
- Genetics and Aging Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA, 02129
| | - Airong Li
- Genetics and Aging Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA, 02129
| | - Chao Zhou
- Department of Electrical and Computer Engineering, Center for Photonics and Nanoelectronics, and Bioengineering Program, Lehigh University, Bethlehem, PA, USA, 18015
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15
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Sassaroli E, Vykhodtseva N. Acoustic neuromodulation from a basic science prospective. J Ther Ultrasound 2016; 4:17. [PMID: 27213044 PMCID: PMC4875658 DOI: 10.1186/s40349-016-0061-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 05/11/2016] [Indexed: 12/11/2022] Open
Abstract
We present here biophysical models to gain deeper insights into how an acoustic stimulus might influence or modulate neuronal activity. There is clear evidence that neural activity is not only associated with electrical and chemical changes but that an electro-mechanical coupling is also involved. Currently, there is no theory that unifies the electrical, chemical, and mechanical aspects of neuronal activity. Here, we discuss biophysical models and hypotheses that can explain some of the mechanical aspects associated with neuronal activity: the soliton model, the neuronal intramembrane cavitation excitation model, and the flexoelectricity hypothesis. We analyze these models and discuss their implications on stimulation and modulation of neuronal activity by ultrasound.
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Affiliation(s)
- Elisabetta Sassaroli
- Department of Radiology, Brigham and Women’s Hospital, Focused Ultrasound Lab, 221 Longwood Ave., Boston, MA 02115 USA
| | - Natalia Vykhodtseva
- Department of Radiology, Brigham and Women’s Hospital, Focused Ultrasound Lab, 221 Longwood Ave., Boston, MA 02115 USA
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16
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Uttam S, Liu Y. Fourier phase in Fourier-domain optical coherence tomography. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2015; 32:2286-306. [PMID: 26831383 PMCID: PMC4741112 DOI: 10.1364/josaa.32.002286] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Phase of an electromagnetic wave propagating through a sample-of-interest is well understood in the context of quantitative phase imaging in transmission-mode microscopy. In the past decade, Fourier-domain optical coherence tomography has been used to extend quantitative phase imaging to the reflection-mode. Unlike transmission-mode electromagnetic phase, however, the origin and characteristics of reflection-mode Fourier phase are poorly understood, especially in samples with a slowly varying refractive index. In this paper, the general theory of Fourier phase from first principles is presented, and it is shown that Fourier phase is a joint estimate of subresolution offset and mean spatial frequency of the coherence-gated sample refractive index. It is also shown that both spectral-domain phase microscopy and depth-resolved spatial-domain low-coherence quantitative phase microscopy are special cases of this general theory. Analytical expressions are provided for both, and simulations are presented to explain and support the theoretical results. These results are further used to show how Fourier phase allows the estimation of an axial mean spatial frequency profile of the sample, along with depth-resolved characterization of localized optical density change and sample heterogeneity. Finally, a Fourier phase-based explanation of Doppler optical coherence tomography is also provided.
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17
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Yeh YJ, Black AJ, Landowne D, Akkin T. Optical coherence tomography for cross-sectional imaging of neural activity. NEUROPHOTONICS 2015. [PMID: 26217674 PMCID: PMC4509668 DOI: 10.1117/1.nph.2.3.035001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We report a functional optical coherence tomography cross-sectional scanner to detect neural activity using unmyelinated nerves dissected from squid. The nerves, unstained or stained with a voltage-sensitive dye, were imaged in a nerve chamber. Transient phase changes from backscattered light were detected during action potential propagation. The results show that the scanner can provide high spatiotemporal resolution cross-sectional images of neural activity ([Formula: see text]; [Formula: see text]; [Formula: see text] in [Formula: see text]). The advantage of this method compared to monitoring a single depth profile [Formula: see text] is a dramatic increase in the number of available sites that can be measured in two spatial dimensions [Formula: see text] with lateral scanning; therefore, the study demonstrates that two-dimensional monitoring of small-scale functional activity would also be feasible.
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Affiliation(s)
- Yi-Jou Yeh
- University of Minnesota, Department of Electrical and Computer Engineering, Minneapolis, Minnesota 55455, United States
- University of Minnesota, Department of Biomedical Engineering, 312 Church Street S.E., Minneapolis, Minnesota 55455, United States
| | - Adam J. Black
- University of Minnesota, Department of Biomedical Engineering, 312 Church Street S.E., Minneapolis, Minnesota 55455, United States
| | - David Landowne
- University of Miami, Department of Physiology and Biophysics, Miami, Florida 33101, United States
| | - Taner Akkin
- University of Minnesota, Department of Biomedical Engineering, 312 Church Street S.E., Minneapolis, Minnesota 55455, United States
- Address all correspondence to: Taner Akkin, E-mail:
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18
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Cell adhesion promotion strategies for signal transduction enhancement in microelectrode array in vitro electrophysiology: An introductory overview and critical discussion. Curr Opin Colloid Interface Sci 2013. [DOI: 10.1016/j.cocis.2013.07.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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19
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Fields RD. Imaging single photons and intrinsic optical signals for studies of vesicular and non-vesicular ATP release from axons. Front Neuroanat 2011; 5:32. [PMID: 21852965 PMCID: PMC3151621 DOI: 10.3389/fnana.2011.00032] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 05/26/2011] [Indexed: 12/12/2022] Open
Abstract
The temporal and spatial dynamics of neurotransmitter release are fundamental to understanding activity-dependent signaling between axons and other cells, including neurons, glia, and vascular cells. A microscopic imaging technique is described that enables studying release of the neurotransmitter ATP from axons in response to action potentials. The method combines imaging single-photons, intrinsic optical signal imaging, and high magnification time-lapse microcopy to enable investigations of action potential-induced ATP release together with cell morphology and activity-dependent axon swelling. ATP released from axons catalyzes a chemiluminescent reaction between luciferin and luciferase that generates single photons that can be imaged individually. In addition to vesicular release, ATP release through membrane channels activated by axon swelling was monitored simultaneously with intrinsic optical signals. Repeated emissions of photons were observed from localized 15 μm regions of axons, with a frequency distribution that differed from a normal distribution and from the frequency of emissions outside these localized regions.
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Affiliation(s)
- R. Douglas Fields
- Nervous Systems Development and Plasticity Section, National Institute of Child Health and Human Development, National Institutes of HealthBethesda, MD, USA
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20
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Fields RD. Nonsynaptic and nonvesicular ATP release from neurons and relevance to neuron-glia signaling. Semin Cell Dev Biol 2011; 22:214-9. [PMID: 21320624 PMCID: PMC3163842 DOI: 10.1016/j.semcdb.2011.02.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 01/11/2011] [Accepted: 02/07/2011] [Indexed: 12/22/2022]
Abstract
Studies on the release of ATP from neurons began with the earliest investigations of quantal neurotransmitter release in the 1950s, but in contrast to ATP release from other cells, studies of ATP release from neurons have been narrowly constrained to one mechanism, vesicular release. This is a consequence of the prominence of synaptic transmission in neuronal communication, but nonvesicular mechanisms for ATP release from neurons are likely to have a broader range of functions than synaptic release. Investigations of activity-dependent communication between axons and myelinating glia have stimulated a search for mechanisms that could release ATP from axons and other nonsynaptic regions in response to action potential firing. This has identified volume-activated anion channels as an important mechanism in activity-dependent ATP release from axons, and renewed interest in micromechanical changes in axons that accompany action potential firing.
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Affiliation(s)
- R Douglas Fields
- Nervous Systems Development and Plasticity Section, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States.
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21
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Abstract
Several physical phenomena accompany the firing of electrical impulses by axons. Some of these, such as the microscopic swelling of axons, alter the transmission of light through axons. This produces what are called "intrinsic optical signals" because optical methods can be used to see axons fire without adding voltage-sensitive dyes or using electronic amplifiers. These physical changes allow neurons tocommunicate through nonsynaptic signals to adjacent cells, such as other neurons or glia. Two of the three videos in this Teaching Resource show the optical manifestations of the microscopic swelling of axons that accompanies the firing of action potentials in cultured neurons, and one shows the nonsynaptic release of ATP that occurs through membrane channels that are stimulated by neuronal swelling.
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Affiliation(s)
- R Douglas Fields
- National Institute of Child Health and Human Development, NIH, Building 35, Room 2A211, MSC3713, Bethesda, MD 20892, USA.
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22
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Li YC, Cui WX, Wang XJ, Amthor F, Lu RW, Thompson A, Yao XC. Intrinsic optical signal imaging of glucose-stimulated insulin secreting β-cells. OPTICS EXPRESS 2011; 19:99-106. [PMID: 21263546 PMCID: PMC3090649 DOI: 10.1364/oe.19.000099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Simultaneous monitoring of many functioning β-cells is essential for understanding β-cell dysfunction as an early event in the progression to diabetes. Intrinsic optical signal (IOS) imaging has been shown to allow high resolution detection of stimulus-evoked physiological responses in the retina and other neural tissues. In this paper, we demonstrate the feasibility of using IOS imaging for functional examination of insulin secreting INS-1 cells, a popular model for investigating diabetes associated β-cell dysfunction. Our experiments indicate that IOS imaging permits simultaneous monitoring of glucose-stimulated physiological responses in multiple cells with high spatial (sub-cellular) and temporal (sub-second) resolution. Rapid IOS image sequences revealed transient optical responses that had time courses tightly correlated with the glucose stimulation.
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Affiliation(s)
- Yi-Chao Li
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294,
USA
- These authors have equivalent contributions
| | - Wan-Xing Cui
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL 35294,
USA
- These authors have equivalent contributions
| | - Xu-Jing Wang
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294,
USA
| | - Franklin Amthor
- Department of Psychology, University of Alabama at Birmingham, Birmingham, AL 35294,
USA
| | - Rong-Wen Lu
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294,
USA
| | - Anthony Thompson
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL 35294,
USA
| | - Xin-Cheng Yao
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294,
USA
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23
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Brownell WE, Qian F, Anvari B. Cell membrane tethers generate mechanical force in response to electrical stimulation. Biophys J 2010; 99:845-52. [PMID: 20682262 PMCID: PMC3297770 DOI: 10.1016/j.bpj.2010.05.025] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 03/25/2010] [Accepted: 05/10/2010] [Indexed: 11/22/2022] Open
Abstract
Living cells maintain a huge transmembrane electric field across their membranes. This electric field exerts a force on the membrane because the membrane surfaces are highly charged. We have measured electromechanical force generation by cell membranes using optically trapped beads to detach the plasma membrane from the cytoskeleton and form long thin cylinders (tethers). Hyperpolarizing potentials increased and depolarizing potentials decreased the force required to pull a tether. The membrane tether force in response to sinusoidal voltage signals was a function of holding potential, tether diameter, and tether length. Membrane electromechanical force production can occur at speeds exceeding those of ATP-based protein motors. By harnessing the energy in the transmembrane electric field, cell membranes may contribute to processes as diverse as outer hair cell electromotility, ion channel gating, and transport.
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Affiliation(s)
- William E Brownell
- Bobby R. Alford Department of Otolaryngology, Head & Neck Surgery, and Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA.
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