101
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Gao M, Yu Y, Zhao H, Li G, Jiang H, Wang C, Cai F, Chan LLH, Chiu B, Qian W, Qiu W, Zheng H. Simulation Study of an Ultrasound Retinal Prosthesis With a Novel Contact-Lens Array for Noninvasive Retinal Stimulation. IEEE Trans Neural Syst Rehabil Eng 2017; 25:1605-1611. [PMID: 28320674 DOI: 10.1109/tnsre.2017.2682923] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Millions of people around the world suffer from varying degrees of vision loss (including complete blindness) because of retinal degenerative diseases. Artificial retinal prosthesis, which is usually based on electrical neurostimulation, is the most advanced technology for different types of retinal degeneration. However, this technology involves placing a device into the eyeball, and such a highly invasive procedure is inevitably highly risk and expensive. Ultrasound has been demonstrated to be a promising technology for noninvasive neurostimulation, making it possible to stimulate the retina and induce action potentials similar to those elicited by light stimulation. However, the technology of ultrasound retinal stimulation still requires considerable developments before it could be applied clinically. This paper proposes a novel contact-lens array transducer for use in an ultrasound retinal prosthesis (USRP). The transducer was designed in the shape of a contact lens so as to facilitate acoustic coupling with the eye liquid. The key parameters of the ultrasound transducer were simulated, and results are presented that indicate the achievement of 2-D pattern generation and that the proposed contact-lens array is suitable for multiple-focus neurostimulation, and can be used in a USRP.
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102
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Zhang BJ, Chamanzar M, Alam MR. Suppression of epileptic seizures via Anderson localization. J R Soc Interface 2017; 14:rsif.2016.0872. [PMID: 28179547 DOI: 10.1098/rsif.2016.0872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 01/16/2017] [Indexed: 11/12/2022] Open
Abstract
Here we show that brain seizures can be effectively suppressed through random modulation of the brain medium. We use an established mesoscale cortical model in the form of a system of coupled stochastic partial differential equations. We show that by temporal and spatial randomization of parameters governing the firing rates of the excitatory and inhibitory neuron populations, seizure waves can be significantly suppressed. We find that the attenuation is the most effective when applied to the mean threshold potential. The proposed technique can serve as a non-invasive paradigm to mitigate epileptic seizures without knowing the location of the epileptic foci.
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Affiliation(s)
- Benjamin J Zhang
- Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA
| | - Maysamreza Chamanzar
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720, USA.,Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Mohammad-Reza Alam
- Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA
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103
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Hynynen K, Jones RM. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy. Phys Med Biol 2016; 61:R206-48. [PMID: 27494561 PMCID: PMC5022373 DOI: 10.1088/0031-9155/61/17/r206] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.
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Affiliation(s)
- Kullervo Hynynen
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada. Department of Medical Biophysics, University of Toronto, Toronto, Canada. Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
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104
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Goetz GA, Palanker DV. Electronic approaches to restoration of sight. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:096701. [PMID: 27502748 PMCID: PMC5031080 DOI: 10.1088/0034-4885/79/9/096701] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Retinal prostheses are a promising means for restoring sight to patients blinded by the gradual atrophy of photoreceptors due to retinal degeneration. They are designed to reintroduce information into the visual system by electrically stimulating surviving neurons in the retina. This review outlines the concepts and technologies behind two major approaches to retinal prosthetics: epiretinal and subretinal. We describe how the visual system responds to electrical stimulation. We highlight major differences between direct encoding of the retinal output with epiretinal stimulation, and network-mediated response with subretinal stimulation. We summarize results of pre-clinical evaluation of prosthetic visual functions in- and ex vivo, as well as the outcomes of current clinical trials of various retinal implants. We also briefly review alternative, non-electronic, approaches to restoration of sight to the blind, and conclude by suggesting some perspectives for future advancement in the field.
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Affiliation(s)
- G A Goetz
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA. Neurosurgery, Stanford University, Stanford, CA 94305, USA
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105
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Ha S, Khraiche ML, Akinin A, Jing Y, Damle S, Kuang Y, Bauchner S, Lo YH, Freeman WR, Silva GA, Cauwenberghs G. Towards high-resolution retinal prostheses with direct optical addressing and inductive telemetry. J Neural Eng 2016; 13:056008. [PMID: 27529371 DOI: 10.1088/1741-2560/13/5/056008] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. APPROACH The hybrid optical addressability and electronic powering scheme provides separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high-throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for common voltage stimulation. MAIN RESULTS A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. SIGNIFICANCE Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.
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Affiliation(s)
- Sohmyung Ha
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093 USA. Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, 92093 USA
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106
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Yuan Y, Yan J, Ma Z, Li X. Noninvasive Focused Ultrasound Stimulation Can Modulate Phase-Amplitude Coupling between Neuronal Oscillations in the Rat Hippocampus. Front Neurosci 2016; 10:348. [PMID: 27499733 PMCID: PMC4956652 DOI: 10.3389/fnins.2016.00348] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 07/11/2016] [Indexed: 11/13/2022] Open
Abstract
Noninvasive focused ultrasound stimulation (FUS) can be used to modulate neural activity with high spatial resolution. Phase-amplitude coupling (PAC) between neuronal oscillations is tightly associated with cognitive processes, including learning, attention, and memory. In this study, we investigated the effect of FUS on PAC between neuronal oscillations and established the relationship between the PAC index and ultrasonic intensity. The rat hippocampus was stimulated using focused ultrasound at different spatial-average pulse-average ultrasonic intensities (3.9, 9.6, and 19.2 W/cm(2)). The local field potentials (LFPs) in the rat hippocampus were recorded before and after FUS. Then, we analyzed PAC between neuronal oscillations using a PAC calculation algorithm. Our results showed that FUS significantly modulated PAC between the theta (4-8 Hz) and gamma (30-80 Hz) bands and between the alpha (9-13 Hz) and ripple (81-200 Hz) bands in the rat hippocampus, and PAC increased with incremental increases in ultrasonic intensity.
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Affiliation(s)
- Yi Yuan
- Institute of Electrical Engineering, Yanshan University Qinhuangdao, China
| | - Jiaqing Yan
- School of Electrical and Control Engineering, North China University of Technology Beijing, China
| | - Zhitao Ma
- Institute of Electrical Engineering, Yanshan University Qinhuangdao, China
| | - Xiaoli Li
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal UniversityBeijing, China; Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal UniversityBeijing, China
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107
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Ye PP, Brown JR, Pauly KB. Frequency Dependence of Ultrasound Neurostimulation in the Mouse Brain. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:1512-30. [PMID: 27090861 PMCID: PMC4899295 DOI: 10.1016/j.ultrasmedbio.2016.02.012] [Citation(s) in RCA: 158] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/15/2016] [Accepted: 02/16/2016] [Indexed: 05/04/2023]
Abstract
Ultrasound neuromodulation holds promise as a non-invasive technique for neuromodulation of the central nervous system. However, much remains to be determined about how the technique can be transformed into a useful technology, including the effect of ultrasound frequency. Previous studies have demonstrated neuromodulation in vivo using frequencies <1 MHz, with a trend toward improved efficacy with lower frequency. However, using higher frequencies could offer improved ultrasound spatial resolution. We investigate the ultrasound neuromodulation effects in mice at various frequencies both below and above 1 MHz. We find that frequencies up to 2.9 MHz can still be effective for generating motor responses, but we also confirm that as frequency increases, sonications require significantly more intensity to achieve equivalent efficacy. We argue that our results provide evidence that favors either a particle displacement or a cavitation-based mechanism for the phenomenon of ultrasound neuromodulation.
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Affiliation(s)
| | - Julian R Brown
- Howard Hughes Medical Institute, Department of Neurobiology, Stanford University, Stanford, CA, USA
| | - Kim Butts Pauly
- Department of Radiology, Stanford University, Stanford, CA, USA
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108
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Yue L, Weiland JD, Roska B, Humayun MS. Retinal stimulation strategies to restore vision: Fundamentals and systems. Prog Retin Eye Res 2016; 53:21-47. [DOI: 10.1016/j.preteyeres.2016.05.002] [Citation(s) in RCA: 173] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 05/13/2016] [Accepted: 05/21/2016] [Indexed: 11/28/2022]
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109
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Cell-Type-Selective Effects of Intramembrane Cavitation as a Unifying Theoretical Framework for Ultrasonic Neuromodulation. eNeuro 2016; 3:eN-NWR-0136-15. [PMID: 27390775 PMCID: PMC4917736 DOI: 10.1523/eneuro.0136-15.2016] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 04/30/2016] [Accepted: 05/10/2016] [Indexed: 11/21/2022] Open
Abstract
Diverse translational and research applications could benefit from the noninvasive ability to reversibly modulate (excite or suppress) CNS activity using ultrasound pulses, however, without clarifying the underlying mechanism, advanced design-based ultrasonic neuromodulation remains elusive. Recently, intramembrane cavitation within the bilayer membrane was proposed to underlie both the biomechanics and the biophysics of acoustic bio-effects, potentially explaining cortical stimulation results through a neuronal intramembrane cavitation excitation (NICE) model. Here, NICE theory is shown to provide a detailed predictive explanation for the ability of ultrasonic (US) pulses to also suppress neural circuits through cell-type-selective mechanisms: according to the predicted mechanism T-type calcium channels boost charge accumulation between short US pulses selectively in low threshold spiking interneurons, promoting net cortical network inhibition. The theoretical results fit and clarify a wide array of earlier empirical observations in both the cortex and thalamus regarding the dependence of ultrasonic neuromodulation outcomes (excitation-suppression) on stimulation and network parameters. These results further support a unifying hypothesis for ultrasonic neuromodulation, highlighting the potential of advanced waveform design for obtaining cell-type-selective network control.
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110
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Abstract
Ultrasonic waves can be non-invasively steered and focused into mm-scale regions across the human body and brain, and their application in generating controlled artificial modulation of neuronal activity could therefore potentially have profound implications for neural science and engineering. Ultrasonic neuro-modulation phenomena were experimentally observed and studied for nearly a century, with recent discoveries on direct neural excitation and suppression sparking a new wave of investigations in models ranging from rodents to humans. In this paper we review the physics, engineering and scientific aspects of ultrasonic fields, their control in both space and time, and their effect on neuronal activity, including a survey of both the field's foundational history and of recent findings. We describe key constraints encountered in this field, as well as key engineering systems developed to surmount them. In closing, the state of the art is discussed, with an emphasis on emerging research and clinical directions.
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Affiliation(s)
- Omer Naor
- Department of Biomedical Engineering, The Technion-Israel Institute of Technology Haifa 32000, Israel. The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91220, Israel
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111
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Kubanek J, Shi J, Marsh J, Chen D, Deng C, Cui J. Ultrasound modulates ion channel currents. Sci Rep 2016; 6:24170. [PMID: 27112990 PMCID: PMC4845013 DOI: 10.1038/srep24170] [Citation(s) in RCA: 198] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 03/22/2016] [Indexed: 12/15/2022] Open
Abstract
Transcranial focused ultrasound (US) has been demonstrated to stimulate neurons in animals and humans, but the mechanism of this effect is unknown. It has been hypothesized that US, a mechanical stimulus, may mediate cellular discharge by activating mechanosensitive ion channels embedded within cellular membranes. To test this hypothesis, we expressed potassium and sodium mechanosensitive ion channels (channels of the two-pore-domain potassium family (K2P) including TREK-1, TREK-2, TRAAK; NaV1.5) in the Xenopus oocyte system. Focused US (10 MHz, 0.3-4.9 W/cm(2)) modulated the currents flowing through the ion channels on average by up to 23%, depending on channel and stimulus intensity. The effects were reversible upon repeated stimulation and were abolished when a channel blocker (ranolazine to block NaV1.5, BaCl2 to block K2P channels) was applied to the solution. These data reveal at the single cell level that focused US modulates the activity of specific ion channels to mediate transmembrane currents. These findings open doors to investigations of the effects of US on ion channels expressed in neurons, retinal cells, or cardiac cells, which may lead to important medical applications. The findings may also pave the way to the development of sonogenetics: a non-invasive, US-based analogue of optogenetics.
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Affiliation(s)
- Jan Kubanek
- Department of Molecular and Cellular Physiology, 279 Campus Drive, Stanford University, Stanford, CA 94305, USA
- Department of Biomedical Engineering, One Brookings Dr., Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, One Brookings Dr., Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Jon Marsh
- Department of Internal Medicine, 4320 Forest Park Ave, Washington University, St. Louis, MO 63110, USA
| | - Di Chen
- Department of Biomedical Engineering, 2200 Bonisteel Blvd.,University of Michigan, Ann Arbor, MI 48109, USA
| | - Cheri Deng
- Department of Biomedical Engineering, 2200 Bonisteel Blvd.,University of Michigan, Ann Arbor, MI 48109, USA
| | - Jianmin Cui
- Department of Biomedical Engineering, One Brookings Dr., Washington University in St. Louis, St. Louis, MO 63130, USA
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112
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Abstract
Optogenetic methodology enables direct targeting of specific neural circuit elements for inhibition or excitation while spanning timescales from the acute (milliseconds) to the chronic (many days or more). Although the impact of this temporal versatility and cellular specificity has been greater for basic science than clinical research, it is natural to ask whether the dynamic patterns of neural circuit activity discovered to be causal in adaptive or maladaptive behaviors could become targets for treatment of neuropsychiatric diseases. Here, we consider the landscape of ideas related to therapeutic targeting of circuit dynamics. Specifically, we highlight optical, ultrasonic, and magnetic concepts for the targeted control of neural activity, preclinical/clinical discovery opportunities, and recently reported optogenetically guided clinical outcomes.
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Affiliation(s)
| | - Emily Ferenczi
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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113
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Abstract
Neural stimulation is a critical technique in treating neurological diseases and investigating brain functions. Traditional electrical stimulation uses electrodes to directly create intervening electric fields in the immediate vicinity of neural tissues. Second-generation stimulation techniques directly use light, magnetic fields or ultrasound in a non-contact manner. An emerging generation of non- or minimally invasive neural stimulation techniques is enabled by nanotechnology to achieve a high spatial resolution and cell-type specificity. In these techniques, a nanomaterial converts a remotely transmitted primary stimulus such as a light, magnetic or ultrasonic signal to a localized secondary stimulus such as an electric field or heat to stimulate neurons. The ease of surface modification and bio-conjugation of nanomaterials facilitates cell-type-specific targeting, designated placement and highly localized membrane activation. This review focuses on nanomaterial-enabled neural stimulation techniques primarily involving opto-electric, opto-thermal, magneto-electric, magneto-thermal and acousto-electric transduction mechanisms. Stimulation techniques based on other possible transduction schemes and general consideration for these emerging neurotechnologies are also discussed.
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Affiliation(s)
- Yongchen Wang
- Department of Biomedical Engineering, The Ohio State University Columbus, OH, USA
| | - Liang Guo
- Department of Electrical and Computer Engineering, The Ohio State UniversityColumbus, OH, USA; Department of Neuroscience, The Ohio State UniversityColumbus, OH, USA
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114
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Sonogenetics is a non-invasive approach to activating neurons in Caenorhabditis elegans. Nat Commun 2015; 6:8264. [PMID: 26372413 PMCID: PMC4571289 DOI: 10.1038/ncomms9264] [Citation(s) in RCA: 206] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 08/04/2015] [Indexed: 12/30/2022] Open
Abstract
A major challenge in neuroscience is to reliably activate individual neurons, particularly those in deeper brain regions. Current optogenetic approaches require invasive surgical procedures to deliver light of specific wavelengths to target cells to activate or silence them. Here, we demonstrate the use of low-pressure ultrasound as a non-invasive trigger to activate specific ultrasonically sensitized neurons in the nematode, Caenorhabditis elegans. We first show that wild-type animals are insensitive to low-pressure ultrasound and require gas-filled microbubbles to transduce the ultrasound wave. We find that neuron-specific misexpression of TRP-4, the pore-forming subunit of a mechanotransduction channel, sensitizes neurons to ultrasound stimulus, resulting in behavioural outputs. Furthermore, we use this approach to manipulate the function of sensory neurons and interneurons and identify a role for PVD sensory neurons in modifying locomotory behaviours. We suggest that this method can be broadly applied to manipulate cellular functions in vivo. Common optogenetic approaches require surgical procedures to deliver light of specific wavelengths to the target cells. Here the authors demonstrate the use of low-pressure ultrasound as a non-invasive trigger to activate specific neurons in Caenorhabditis elegans and find that the mechanotransduction channel TRP-4 sensitizes cells to the ultrasound stimulus.
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115
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Ghezzi D. Retinal prostheses: progress toward the next generation implants. Front Neurosci 2015; 9:290. [PMID: 26347602 PMCID: PMC4542462 DOI: 10.3389/fnins.2015.00290] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 07/30/2015] [Indexed: 12/18/2022] Open
Abstract
In the last decade, various clinical trials proved the capability of visual prostheses, in particular retinal implants, to restore a useful form of vision. These encouraging results promoted the emerging of several strategies for neuronal stimulation aiming at the restoration of sight. Besides the traditional approach based on electrical stimulation through metal electrodes in the different areas of the visual path (e.g., the visual cortex, the lateral geniculate nucleus, the optic nerve, and the retina), novel concepts for neuronal stimulation have been mostly exploited as building blocks of the next generation of retinal implants. This review is focused on critically discussing recent major advancements in the field of retinal stimulation with particular attention to the findings in the application of novel concepts and materials. Last, the major challenges in the field and their clinical implications will be outlined.
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Affiliation(s)
- Diego Ghezzi
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics, Interfaculty Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne Lausanne, Switzerland
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116
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Nightingale KR, Church CC, Harris G, Wear KA, Bailey MR, Carson PL, Jiang H, Sandstrom KL, Szabo TL, Ziskin MC. Conditionally Increased Acoustic Pressures in Nonfetal Diagnostic Ultrasound Examinations Without Contrast Agents: A Preliminary Assessment. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2015; 34:1-41. [PMID: 26112617 PMCID: PMC4822701 DOI: 10.7863/ultra.34.7.15.13.0001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The mechanical index (MI) has been used by the US Food and Drug Administration (FDA) since 1992 for regulatory decisions regarding the acoustic output of diagnostic ultrasound equipment. Its formula is based on predictions of acoustic cavitation under specific conditions. Since its implementation over 2 decades ago, new imaging modes have been developed that employ unique beam sequences exploiting higher-order acoustic phenomena, and, concurrently, studies of the bioeffects of ultrasound under a range of imaging scenarios have been conducted. In 2012, the American Institute of Ultrasound in Medicine Technical Standards Committee convened a working group of its Output Standards Subcommittee to examine and report on the potential risks and benefits of the use of conditionally increased acoustic pressures (CIP) under specific diagnostic imaging scenarios. The term "conditionally" is included to indicate that CIP would be considered on a per-patient basis for the duration required to obtain the necessary diagnostic information. This document is a result of that effort. In summary, a fundamental assumption in the MI calculation is the presence of a preexisting gas body. For tissues not known to contain preexisting gas bodies, based on theoretical predications and experimentally reported cavitation thresholds, we find this assumption to be invalid. We thus conclude that exceeding the recommended maximum MI level given in the FDA guidance could be warranted without concern for increased risk of cavitation in these tissues. However, there is limited literature assessing the potential clinical benefit of exceeding the MI guidelines in these tissues. The report proposes a 3-tiered approach for CIP that follows the model for employing elevated output in magnetic resonance imaging and concludes with summary recommendations to facilitate Institutional Review Board (IRB)-monitored clinical studies investigating CIP in specific tissues.
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Affiliation(s)
- Kathryn R Nightingale
- Department of Biomedical Engineering, Duke University, PO Box 90281, Durham, NC 27708 USA
| | - Charles C Church
- National Center for Physical Acoustics and Department of Physics and Astronomy, The University of Mississippi, University, MS 38677 USA
| | - Gerald Harris
- US Food and Drug Administration (Retired), Current Address: 132 S Van Buren St, Rockville, MD 20850 USA
| | - Keith A Wear
- US Food and Drug Administration, 10903 New Hampshire Ave, Building 62, Room 2104, Silver Spring, MD 20993-0002 USA
| | - Michael R Bailey
- Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th St, Seattle WA 98105 USA
| | - Paul L Carson
- Department of Radiology, University of Michigan Health System, 3218C Med Sci I, B Wing SPC 5667, Ann Arbor, MI 48109-5667 USA
| | - Hui Jiang
- Fujifilm SonoSite, 21919 30th Dr SE, Bothell, WA 98021 USA
| | - Kurt L Sandstrom
- Samsung Medison Co, Ltd, Building, 42, Teheran-ro, 108-gil, Gangnam-gu, Seoul 135-851, Korea
| | - Thomas L Szabo
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215 USA
| | - Marvin C Ziskin
- Emeritus Professor of Radiology and Medical Physics, Temple University School of Medicine, Philadelphia, PA 19140 USA
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117
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Emerging neural stimulation technologies for bladder dysfunctions. Int Neurourol J 2015; 19:3-11. [PMID: 25833475 PMCID: PMC4386488 DOI: 10.5213/inj.2015.19.1.3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 03/10/2015] [Indexed: 01/16/2023] Open
Abstract
In the neural engineering field, physiological dysfunctions are approached by identifying the target nerves and providing artificial stimulation to restore the function. Neural stimulation and recording technologies play a central role in this approach, and various engineering devices and stimulation techniques have become available to the medical community. For bladder control problems, electrical stimulation has been used as one of the treatments, while only a few emerging neurotechnologies have been used to tackle these problems. In this review, we introduce some recent developments in neural stimulation technologies including microelectrode array, closed-loop neural stimulation, optical stimulation, and ultrasound stimulation.
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118
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Mueller JK, Tyler WJ. A quantitative overview of biophysical forces impinging on neural function. Phys Biol 2014; 11:051001. [DOI: 10.1088/1478-3975/11/5/051001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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119
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Luan S, Williams I, Nikolic K, Constandinou TG. Neuromodulation: present and emerging methods. FRONTIERS IN NEUROENGINEERING 2014; 7:27. [PMID: 25076887 PMCID: PMC4097946 DOI: 10.3389/fneng.2014.00027] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 06/24/2014] [Indexed: 12/21/2022]
Abstract
Neuromodulation has wide ranging potential applications in replacing impaired neural function (prosthetics), as a novel form of medical treatment (therapy), and as a tool for investigating neurons and neural function (research). Voltage and current controlled electrical neural stimulation (ENS) are methods that have already been widely applied in both neuroscience and clinical practice for neuroprosthetics. However, there are numerous alternative methods of stimulating or inhibiting neurons. This paper reviews the state-of-the-art in ENS as well as alternative neuromodulation techniques-presenting the operational concepts, technical implementation and limitations-in order to inform system design choices.
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Affiliation(s)
- Song Luan
- Department of Electrical and Electronic Engineering, Imperial College LondonLondon, UK
- Center for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College LondonLondon, UK
| | - Ian Williams
- Department of Electrical and Electronic Engineering, Imperial College LondonLondon, UK
- Center for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College LondonLondon, UK
| | - Konstantin Nikolic
- Department of Electrical and Electronic Engineering, Imperial College LondonLondon, UK
- Center for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College LondonLondon, UK
| | - Timothy G. Constandinou
- Department of Electrical and Electronic Engineering, Imperial College LondonLondon, UK
- Center for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College LondonLondon, UK
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Kastner DB, Baccus SA. Insights from the retina into the diverse and general computations of adaptation, detection, and prediction. Curr Opin Neurobiol 2014; 25:63-9. [DOI: 10.1016/j.conb.2013.11.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/24/2013] [Accepted: 11/28/2013] [Indexed: 01/26/2023]
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Transcranial focused ultrasound modulates the activity of primary somatosensory cortex in humans. Nat Neurosci 2014; 17:322-9. [PMID: 24413698 DOI: 10.1038/nn.3620] [Citation(s) in RCA: 539] [Impact Index Per Article: 53.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 12/04/2013] [Indexed: 01/26/2023]
Abstract
Improved methods of noninvasively modulating human brain function are needed. Here we probed the influence of transcranial focused ultrasound (tFUS) targeted to the human primary somatosensory cortex (S1) on sensory-evoked brain activity and sensory discrimination abilities. The lateral and axial spatial resolution of the tFUS beam implemented were 4.9 mm and 18 mm, respectively. Electroencephalographic recordings showed that tFUS significantly attenuated the amplitudes of somatosensory evoked potentials elicited by median nerve stimulation. We also found that tFUS significantly modulated the spectral content of sensory-evoked brain oscillations. The changes produced by tFUS on sensory-evoked brain activity were abolished when the acoustic beam was focused 1 cm anterior or posterior to S1. Behavioral investigations showed that tFUS targeted to S1 enhanced performance on sensory discrimination tasks without affecting task attention or response bias. We conclude that tFUS can be used to focally modulate human cortical function.
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Abstract
PURPOSE OF REVIEW Outer retinal degenerations such as retinitis pigmentosa can cause profound vision loss. Various treatment strategies are being pursued to potentially restore functional vision in these patients. RECENT FINDINGS Advances in retinal prostheses have restored some vision in patients previously blind from retinitis pigmentosa. Optogenetics is another area that shows promise for restoration of vision. Transcorneal electrostimulation shows some efficacy to treat these patients as well. SUMMARY We review recent advances in optogenetics, visual prosthesis and electrostimulation to treat outer retinal degenerations.
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Dynamic response of model lipid membranes to ultrasonic radiation force. PLoS One 2013; 8:e77115. [PMID: 24194863 PMCID: PMC3806737 DOI: 10.1371/journal.pone.0077115] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/29/2013] [Indexed: 12/14/2022] Open
Abstract
Low-intensity ultrasound can modulate action potential firing in neurons in vitro and in vivo. It has been suggested that this effect is mediated by mechanical interactions of ultrasound with neural cell membranes. We investigated whether these proposed interactions could be reproduced for further study in a synthetic lipid bilayer system. We measured the response of protein-free model membranes to low-intensity ultrasound using electrophysiology and laser Doppler vibrometry. We find that ultrasonic radiation force causes oscillation and displacement of lipid membranes, resulting in small (<1%) changes in membrane area and capacitance. Under voltage-clamp, the changes in capacitance manifest as capacitive currents with an exponentially decaying sinusoidal time course. The membrane oscillation can be modeled as a fluid dynamic response to a step change in pressure caused by ultrasonic radiation force, which disrupts the balance of forces between bilayer tension and hydrostatic pressure. We also investigated the origin of the radiation force acting on the bilayer. Part of the radiation force results from the reflection of the ultrasound from the solution/air interface above the bilayer (an effect that is specific to our experimental configuration) but part appears to reflect a direct interaction of ultrasound with the bilayer, related to either acoustic streaming or scattering of sound by the bilayer. Based on these results, we conclude that synthetic lipid bilayers can be used to study the effects of ultrasound on cell membranes and membrane proteins.
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