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Lu G, Gong C, Sun Y, Qian X, Rajendran Nair DS, Li R, Zeng Y, Ji J, Zhang J, Kang H, Jiang L, Chen J, Chang CF, Thomas BB, Humayun MS, Zhou Q. Noninvasive imaging-guided ultrasonic neurostimulation with arbitrary 2D patterns and its application for high-quality vision restoration. Nat Commun 2024; 15:4481. [PMID: 38802397 PMCID: PMC11130148 DOI: 10.1038/s41467-024-48683-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 05/09/2024] [Indexed: 05/29/2024] Open
Abstract
Retinal degeneration, a leading cause of irreversible low vision and blindness globally, can be partially addressed by retina prostheses which stimulate remaining neurons in the retina. However, existing electrode-based treatments are invasive, posing substantial risks to patients and healthcare providers. Here, we introduce a completely noninvasive ultrasonic retina prosthesis, featuring a customized ultrasound two-dimensional array which allows for simultaneous imaging and stimulation. With synchronous three-dimensional imaging guidance and auto-alignment technology, ultrasonic retina prosthesis can generate programmed ultrasound waves to dynamically and precisely form arbitrary wave patterns on the retina. Neuron responses in the brain's visual center mirrored these patterns, evidencing successful artificial vision creation, which was further corroborated in behavior experiments. Quantitative analysis of the spatial-temporal resolution and field of view demonstrated advanced performance of ultrasonic retina prosthesis and elucidated the biophysical mechanism of retinal stimulation. As a noninvasive blindness prosthesis, ultrasonic retina prosthesis could lead to a more effective, widely acceptable treatment for blind patients. Its real-time imaging-guided stimulation strategy with a single ultrasound array, could also benefit ultrasound neurostimulation in other diseases.
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Affiliation(s)
- Gengxi Lu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Chen Gong
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Yizhe Sun
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Xuejun Qian
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Deepthi S Rajendran Nair
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Runze Li
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Yushun Zeng
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Jie Ji
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Junhang Zhang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Haochen Kang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Laiming Jiang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Jiawen Chen
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Chi-Feng Chang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Biju B Thomas
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Mark S Humayun
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA, USA
| | - Qifa Zhou
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.
- Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA, USA.
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Stoddart PR, Begeng JM, Tong W, Ibbotson MR, Kameneva T. Nanoparticle-based optical interfaces for retinal neuromodulation: a review. Front Cell Neurosci 2024; 18:1360870. [PMID: 38572073 PMCID: PMC10987880 DOI: 10.3389/fncel.2024.1360870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 03/04/2024] [Indexed: 04/05/2024] Open
Abstract
Degeneration of photoreceptors in the retina is a leading cause of blindness, but commonly leaves the retinal ganglion cells (RGCs) and/or bipolar cells extant. Consequently, these cells are an attractive target for the invasive electrical implants colloquially known as "bionic eyes." However, after more than two decades of concerted effort, interfaces based on conventional electrical stimulation approaches have delivered limited efficacy, primarily due to the current spread in retinal tissue, which precludes high-acuity vision. The ideal prosthetic solution would be less invasive, provide single-cell resolution and an ability to differentiate between different cell types. Nanoparticle-mediated approaches can address some of these requirements, with particular attention being directed at light-sensitive nanoparticles that can be accessed via the intrinsic optics of the eye. Here we survey the available known nanoparticle-based optical transduction mechanisms that can be exploited for neuromodulation. We review the rapid progress in the field, together with outstanding challenges that must be addressed to translate these techniques to clinical practice. In particular, successful translation will likely require efficient delivery of nanoparticles to stable and precisely defined locations in the retinal tissues. Therefore, we also emphasize the current literature relating to the pharmacokinetics of nanoparticles in the eye. While considerable challenges remain to be overcome, progress to date shows great potential for nanoparticle-based interfaces to revolutionize the field of visual prostheses.
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Affiliation(s)
- Paul R. Stoddart
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - James M. Begeng
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
| | - Wei Tong
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC, Australia
| | - Michael R. Ibbotson
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
| | - Tatiana Kameneva
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
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Lu JY, Lu G, Thomas BB, Humayun MS, Zhou Q. Ultrasound Concave 2-D Ring Array for Retinal Stimulation. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2023; 70:1527-1535. [PMID: 37792653 PMCID: PMC10657748 DOI: 10.1109/tuffc.2023.3321871] [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: 10/06/2023]
Abstract
An ultrasound concave 2-D ring array transducer was designed for applications in visual stimulation of the retina with a long-term goal to restore vision in individuals with intact neurons but suffering blindness due to retinopathies. The array was synthesized and has a frequency of 20 MHz (0.075-mm wavelengths in water), 18-mm focal length (the curvature of the concave array), 1004 elements (with a pitch of 4.0 wavelengths), and inner and outer diameters of 9 and 14 mm, respectively. Wave patterns produced with the array at the focal distance were simulated. Results show that the wave patterns obtained can achieve a full-width-at-half-maximum (FWHM) resolution of 0.147 mm that is very close to the FWHM diffraction limit (0.136 mm). In addition, a scaled experiment at a lower frequency of 2.5 MHz was performed. The result is very close to those obtained with the simulations.
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Zhong YX, Liao JC, Liu X, Tian H, Deng LR, Long L. Low intensity focused ultrasound: a new prospect for the treatment of Parkinson's disease. Ann Med 2023; 55:2251145. [PMID: 37634059 PMCID: PMC10461511 DOI: 10.1080/07853890.2023.2251145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/17/2023] [Accepted: 08/20/2023] [Indexed: 08/28/2023] Open
Abstract
Background: As a chronic and progressive neurodegenerative disease, Parkinson's disease (PD) still lacks effective and safe targeted drug therapy. Low-intensity focused ultrasound (LIFU), a new method to stimulate the brain and open the blood-brain barrier (BBB), has been widely concerned by PD researchers due to its non-invasive characteristics.Methods: PubMed was searched for the past 10 years using the terms 'focused ultrasound', 'transcranial ultrasound', 'pulse ultrasound', and 'Parkinson's disease'. Relevant citations were selected from the authors' references. After excluding articles describing high-intensity focused ultrasound or non-Parkinson's disease applications, we found more than 100 full-text analyses for pooled analysis.Results: Current preclinical studies have shown that LIFU could improve PD motor symptoms by regulating microglia activation, increasing neurotrophic factors, reducing oxidative stress, and promoting nerve repair and regeneration, while LIFU combined with microbubbles (MBs) can promote drugs to cross the BBB, which may become a new direction of PD treatment. Therefore, finding an efficient drug carrier system is the top priority of applying LIFU with MBs to deliver drugs.Conclusions: This article aims to review neuro-modulatory effect of LIFU and the possible biophysical mechanism in the treatment of PD, summarize the latest progress in delivering vehicles with MBs, and discuss its advantages and limitations.
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Affiliation(s)
- Yun-Xiao Zhong
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jin-Chi Liao
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xv Liu
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Hao Tian
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Li-Ren Deng
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ling Long
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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Lee MH, Lew HM, Youn S, Kim T, Hwang JY. Deep Learning-Based Framework for Fast and Accurate Acoustic Hologram Generation. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 69:3353-3366. [PMID: 36331635 DOI: 10.1109/tuffc.2022.3219401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Acoustic holography has been gaining attention for various applications, such as noncontact particle manipulation, noninvasive neuromodulation, and medical imaging. However, only a few studies on how to generate acoustic holograms have been conducted, and even conventional acoustic hologram algorithms show limited performance in the fast and accurate generation of acoustic holograms, thus hindering the development of novel applications. We here propose a deep learning-based framework to achieve fast and accurate acoustic hologram generation. The framework has an autoencoder-like architecture; thus, the unsupervised training is realized without any ground truth. For the framework, we demonstrate a newly developed hologram generator network, the holographic ultrasound generation network (HU-Net), which is suitable for unsupervised learning of hologram generation, and a novel loss function that is devised for energy-efficient holograms. Furthermore, for considering various hologram devices (i.e., ultrasound transducers), we propose a physical constraint (PC) layer. Simulation and experimental studies were carried out for two different hologram devices, such as a 3-D printed lens, attached to a single element transducer, and a 2-D ultrasound array. The proposed framework was compared with the iterative angular spectrum approach (IASA) and the state-of-the-art (SOTA) iterative optimization method, Diff-PAT. In the simulation study, our framework showed a few hundred times faster generation speed, along with comparable or even better reconstruction quality, than those of IASA and Diff-PAT. In the experimental study, the framework was validated with 3-D printed lenses fabricated based on different methods, and the physical effect of the lenses on the reconstruction quality was discussed. The outcomes of the proposed framework in various cases (i.e., hologram generator networks, loss functions, and hologram devices) suggest that our framework may become a very useful alternative tool for other existing acoustic hologram applications, and it can expand novel medical applications.
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Lu G, Qian X, Gong C, Ji J, Thomas BB, Humayun MS, Zhou Q. Ultrasound Retinal Stimulation: A Mini-Review of Recent Developments. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 69:3224-3231. [PMID: 36343006 PMCID: PMC10424795 DOI: 10.1109/tuffc.2022.3220568] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Ultrasound neuromodulation is an emerging technology. A significant amount of effort has been devoted to investigating the feasibility of noninvasive ultrasound retinal stimulation. Recent studies have shown that ultrasound can activate neurons in healthy and degenerated retinas. Specifically, high-frequency ultrasound can evoke localized neuron responses and generate patterns in visual circuits. In this review, we recapitulate pilot studies on ultrasound retinal stimulation, compare it with other neuromodulation technologies, and discuss its advantages and limitations. An overview of the opportunities and challenges to develop a noninvasive retinal prosthesis using high-frequency ultrasound is also provided.
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Xu C, Lu G, Kang H, Humayun MS, Zhou Q. Design and Simulation of a Ring Transducer Array for Ultrasound Retinal Stimulation. MICROMACHINES 2022; 13:1536. [PMID: 36144157 PMCID: PMC9503310 DOI: 10.3390/mi13091536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/22/2022] [Accepted: 09/10/2022] [Indexed: 06/16/2023]
Abstract
Argus II retinal prosthesis is the US Food and Drug Administration (FDA) approved medical device intended to restore sight to a patient's blind secondary to retinal degeneration (i.e., retinitis pigmentosa). However, Argus II and most reported retinal prostheses require invasive surgery to implant electrodes in the eye. Recent studies have shown that focused ultrasound can be developed into a non-invasive retinal prosthesis technology. Ultrasound energy focused on retinal neurons can trigger the activities of retinal neurons with high spatial-temporal resolution. This paper introduces a novel design and simulation of a ring array transducer that could be used as non-invasive ultrasonic retinal stimulation. The array transducer is designed in the shape of a racing ring with a hemisphere surface that mimics a contact lens to acoustically couple with the eye via the tear film and directs the ultrasound to avoid the high acoustic absorption from the crystalline lens. We will describe the design methods and simulation of the two-dimensional pattern stimulation. Finally, compared with other existing retinal prostheses, we show that the ultrasound ring array is practical and safe and could be potentially used as a non-invasive retinal prosthesis.
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Affiliation(s)
- Chenlin Xu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Gengxi Lu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Haochen Kang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Mark S. Humayun
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
| | - Qifa Zhou
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
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Badadhe JD, Roh H, Lee BC, Kim JH, Im M. Ultrasound stimulation for non-invasive visual prostheses. Front Cell Neurosci 2022; 16:971148. [PMID: 35990889 PMCID: PMC9382087 DOI: 10.3389/fncel.2022.971148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 07/18/2022] [Indexed: 12/04/2022] Open
Abstract
Globally, it is estimated there are more than 2.2 billion visually impaired people. Visual diseases such as retinitis pigmentosa, age-related macular degeneration, glaucoma, and optic neuritis can cause irreversible profound vision loss. Many groups have investigated different approaches such as microelectronic prostheses, optogenetics, stem cell therapy, and gene therapy to restore vision. However, these methods have some limitations such as invasive implantation surgery and unknown long-term risk of genetic manipulation. In addition to the safety of ultrasound as a medical imaging modality, ultrasound stimulation can be a viable non-invasive alternative approach for the sight restoration because of its ability to non-invasively control neuronal activities. Indeed, recent studies have demonstrated ultrasound stimulation can successfully modulate retinal/brain neuronal activities without causing any damage to the nerve cells. Superior penetration depth and high spatial resolution of focused ultrasound can open a new avenue in neuromodulation researches. This review summarizes the latest research results about neural responses to ultrasound stimulation. Also, this work provides an overview of technical viewpoints in the future design of a miniaturized ultrasound transducer for a non-invasive acoustic visual prosthesis for non-surgical and painless restoration of vision.
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Affiliation(s)
- Jaya Dilip Badadhe
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
| | - Hyeonhee Roh
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- School of Electrical Engineering, College of Engineering, Korea University, Seoul, South Korea
| | - Byung Chul Lee
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul, South Korea
| | - Jae Hun Kim
- Sensor System Research Center, Korea Institute of Science and Technology (KIST), Seoul, South Korea
| | - Maesoon Im
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
- *Correspondence: Maesoon Im, ;
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Zhuo SY, Li GF, Gong HQ, Qiu WB, Zheng HR, Liang PJ. Low-frequency, low-intensity ultrasound modulates light responsiveness of mouse retinal ganglion cells. J Neural Eng 2022; 19. [PMID: 35772385 DOI: 10.1088/1741-2552/ac7d75] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/30/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Ultrasound modulates the firing activity of retinal ganglion cells (RGCs), but the effects of lower-frequency, lower-intensity ultrasound on RGCs and underlying mechanism(s) remain poorly understood. This study aims to address these questions. APPROACH Multi-electrode recordings were used in this study to record the firing sequences of RGCs in isolated mouse retinas. RGCs' background firing activities as well as their light responses were recorded with or without ultrasound stimulation. Cross-correlation analyses were performed to investigate the possible cellular/circuitry mechanism(s) underlying ultrasound modulation. MAIN RESULTS It was found that ultrasound stimulation of isolated mouse retina enhanced the background activity of ON-RGCs and OFF-RGCs. In addition, background ultrasound stimulation shortened the light response latency of both ON-RGCs and OFF-RGCs, while enhancing part of the RGCs' (both ON- and OFF-subtypes) light response and decreasing that of the others. In some ON-OFF RGCs, the ON- and OFF-responses of an individual cell were oppositely modulated by the ultrasound stimulation, which suggests that ultrasound stimulation does not necessarily exert its effect directly on RGCs, but rather via its influence on other type(s) of cells. By analyzing the cross-correlation between the firing sequences of RGC pairs, it was found that concerted activity occurred during ultrasound stimulation differed from that occurred during light stimulation, in both spatial and temporal aspects. These results suggest that the cellular circuits involved in ultrasound- and light-induced concerted activities are different and glial cells may be involved in the circuit in response to ultrasound. SIGNIFICANCE These findings demonstrate that ultrasound affects neuronal background activity and light responsiveness, which are critical for visual information processing. These results may also imply a hitherto unrecognized role of glial cell activation in the bidirectional modulation effects of RGCs and may be critical for the nervous system.
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Affiliation(s)
- Shun-Yi Zhuo
- Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, CHINA
| | - Guo-Feng Li
- Guangdong Medical University, Songshan Lake Science and Technology Park, Dongguan, Guangdong, 523000, CHINA
| | - Hai-Qing Gong
- School of Biomedical Engineering, Shanghai Jiao Tong University, Dongchuan 800 road, Shanghai, 200240, CHINA
| | - Wei-Bao Qiu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Ave.,, Nanshan, Shenzhen, Guangdong, 518055, CHINA
| | - Hai-Rong Zheng
- Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Shenzhen Institutes of Advanced Technology, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen, P.R.China, Shenzhen, 518055, CHINA
| | - Pei-Ji Liang
- School of Biomedical Engineering, Shanghai Jiao Tong University, China, Shanghai, 800 Dongchuan Road, Shanghai, Shanghai, 200240, CHINA
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Zhuang X, He J, Wu J, Ji X, Chen Y, Yuan M, Zeng L. A Spatial Multitarget Ultrasound Neuromodulation System Using High-Powered 2-D Array Transducer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 69:998-1007. [PMID: 34990356 DOI: 10.1109/tuffc.2022.3140889] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Transcranial focused ultrasound (tFUS) is increasingly used in experimental neuroscience due to its neuromodulatory effectiveness in animal studies. However, achieving multitarget tFUS in small animals is typically limited by transducer size, energy transfer efficiency, and brain volume. The objective of this work was to construct an ultrasound system for multitarget neuromodulation in small animals. First, a miniaturized high-powered 2-D array transducer was developed. The phase delay of each array element was calculated based on the multifocal time-reversal method, generating multiple foci simultaneously in a 3-D field. The effects of the axial focal length, interfocus spacing (lateral distance between the two focal centers), and the number of foci on the focal properties of the pressure field were examined through numerical simulations. In-vitro ultrasonic measurements and transcranial simulations on a rat skull were conducted. The minimum interfocus spacing separating two -6-dB foci and the peak full-width at half-maximum were positively correlated with axial focal length; the relative relationship between the interfocus spacing and pressure field properties was similar for each axial focal length. The maximum acoustic pressure and spatial average intensity at focus in deionized water were 2.21 MPa and 133 W/cm2, respectively. The simulated and experimental results were compared, demonstrating agreement in both peak position and focus shape. The ultrasound system can provide a neuroscientific platform for evaluating the feasibility of multitarget ultrasound stimulation treatment protocols, thus improving the understanding of functional neuroanatomy.
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Qian X, Lu G, Thomas BB, Li R, Chen X, Shung KK, Humayun M, Zhou Q. Noninvasive Ultrasound Retinal Stimulation for Vision Restoration at High Spatiotemporal Resolution. BME FRONTIERS 2022; 2022:9829316. [PMID: 37850175 PMCID: PMC10521738 DOI: 10.34133/2022/9829316] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 01/05/2022] [Indexed: 10/19/2023] Open
Abstract
Objective. Retinal degeneration involving progressive deterioration and loss of function of photoreceptors is a major cause of permanent vision loss worldwide. Strategies to treat these incurable conditions incorporate retinal prostheses via electrically stimulating surviving retinal neurons with implanted devices in the eye, optogenetic therapy, and sonogenetic therapy. Existing challenges of these strategies include invasive manner, complex implantation surgeries, and risky gene therapy. Methods and Results. Here, we show that direct ultrasound stimulation on the retina can evoke neuron activities from the visual centers including the superior colliculus and the primary visual cortex (V1), in either normal-sighted or retinal degenerated blind rats in vivo. The neuron activities induced by the customized spherically focused 3.1 MHz ultrasound transducer have shown both good spatial resolution of 250 μm and temporal resolution of 5 Hz in the rat visual centers. An additional customized 4.4 MHz helical transducer was further implemented to generate a static stimulation pattern of letter forms. Conclusion. Our findings demonstrate that ultrasound stimulation of the retina in vivo is a safe and effective approach with high spatiotemporal resolution, indicating a promising future of ultrasound stimulation as a novel and noninvasive visual prosthesis for translational applications in blind patients.
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Affiliation(s)
- Xuejun Qian
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA
| | - Gengxi Lu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA
| | - Biju B. Thomas
- Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA
| | - Runze Li
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA
| | - Xiaoyang Chen
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - K. Kirk Shung
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Mark Humayun
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
| | - Qifa Zhou
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- Department of Ophthalmology, University of Southern California, Los Angeles, CA 90033, USA
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Chen AW, Jeremic A, Zderic V. Ex Vivo Imaging of Ultrasound-Stimulated Metabolic Activity in Rat Pancreatic Slices. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:666-678. [PMID: 33257101 PMCID: PMC7856007 DOI: 10.1016/j.ultrasmedbio.2020.10.021] [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] [Received: 03/18/2020] [Revised: 10/23/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
Ultrasound has previously been reported to produce a reversible stimulatory effect in cultured rat beta cells. Here, we quantified and assessed dynamic metabolic changes in an in situ pancreatic slice model evoked by ultrasound application. After plating, pancreas slices were imaged using a confocal microscope at 488 and 633 nm to image lipodamine dehydrogenase (Lip-DH) autofluorescence and a far red fluorescence, respectively. Ultrasound was applied at intensities of 0.5 and 1 W/cm2 at both 800 kHz and 1 MHz. Additionally, 800 kHz at 1 W/cm2 was applied in a pulsing scheme. No ultrasound (control) and glucose application experiments were performed. A difference in fluorescence signal before and after treatment application was the metric for analysis. Comparison of experimental groups using far red fluorescence revealed significant differences between all experimental groups and control in the islet (p < 0.05) and between all ultrasound experimental groups and control (p < 0.05) in pancreatic exocrine tissue. However, this difference in response between control and glucose did not exist in the exocrine tissue. We also observed using Lip-DH autofluorescence that glucose produces a significantly increased metabolic response in islet tissue compared with exocrine tissue (p < 0.05). Pulsed ultrasound appeared to increase metabolic activity in the pancreatic slice in a more consistent manner compared with continuous ultrasound application. Our results indicate that therapeutic ultrasound may have a stimulatory metabolic effect on the pancreatic islets similar to that of glucose.
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Affiliation(s)
- Andrew W Chen
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - Aleksandar Jeremic
- Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Vesna Zderic
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA.
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Lo PA, Huang K, Zhou Q, Humayun MS, Yue L. Ultrasonic Retinal Neuromodulation and Acoustic Retinal Prosthesis. MICROMACHINES 2020; 11:mi11100929. [PMID: 33066085 PMCID: PMC7600354 DOI: 10.3390/mi11100929] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/11/2020] [Accepted: 10/11/2020] [Indexed: 12/16/2022]
Abstract
Ultrasound is an emerging method for non-invasive neuromodulation. Studies in the past have demonstrated that ultrasound can reversibly activate and inhibit neural activities in the brain. Recent research shows the possibility of using ultrasound ranging from 0.5 to 43 MHz in acoustic frequency to activate the retinal neurons without causing detectable damages to the cells. This review recapitulates pilot studies that explored retinal responses to the ultrasound exposure, discusses the advantages and limitations of the ultrasonic stimulation, and offers an overview of engineering perspectives in developing an acoustic retinal prosthesis. For comparison, this article also presents studies in the ultrasonic stimulation of the visual cortex. Despite that, the summarized research is still in an early stage; ultrasonic retinal stimulation appears to be a viable technology that exhibits enormous therapeutic potential for non-invasive vision restoration.
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Affiliation(s)
- Pei-An Lo
- Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA; (P.-A.L.); (K.H.); (Q.Z.); (M.S.H.)
- Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
| | - Kyana Huang
- Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA; (P.-A.L.); (K.H.); (Q.Z.); (M.S.H.)
| | - Qifa Zhou
- Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA; (P.-A.L.); (K.H.); (Q.Z.); (M.S.H.)
- Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
| | - Mark S. Humayun
- Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA; (P.-A.L.); (K.H.); (Q.Z.); (M.S.H.)
- Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
| | - Lan Yue
- Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA; (P.-A.L.); (K.H.); (Q.Z.); (M.S.H.)
- Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
- Correspondence:
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14
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Shim S, Eom K, Jeong J, Kim SJ. Retinal Prosthetic Approaches to Enhance Visual Perception for Blind Patients. MICROMACHINES 2020; 11:E535. [PMID: 32456341 PMCID: PMC7281011 DOI: 10.3390/mi11050535] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/22/2020] [Accepted: 05/22/2020] [Indexed: 12/14/2022]
Abstract
Retinal prostheses are implantable devices that aim to restore the vision of blind patients suffering from retinal degeneration, mainly by artificially stimulating the remaining retinal neurons. Some retinal prostheses have successfully reached the stage of clinical trials; however, these devices can only restore vision partially and remain insufficient to enable patients to conduct everyday life independently. The visual acuity of the artificial vision is limited by various factors from both engineering and physiological perspectives. To overcome those issues and further enhance the visual resolution of retinal prostheses, a variety of retinal prosthetic approaches have been proposed, based on optimization of the geometries of electrode arrays and stimulation pulse parameters. Other retinal stimulation modalities such as optics, ultrasound, and magnetics have also been utilized to address the limitations in conventional electrical stimulation. Although none of these approaches have been clinically proven to fully restore the function of a degenerated retina, the extensive efforts made in this field have demonstrated a series of encouraging findings for the next generation of retinal prostheses, and these could potentially enhance the visual acuity of retinal prostheses. In this article, a comprehensive and up-to-date overview of retinal prosthetic strategies is provided, with a specific focus on a quantitative assessment of visual acuity results from various retinal stimulation technologies. The aim is to highlight future directions toward high-resolution retinal prostheses.
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Affiliation(s)
- Shinyong Shim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan 46241, Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, College of Information and Biomedical Engineering, Pusan National University, Yangsan 50612, Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
- Institute on Aging, College of Medicine, Seoul National University, Seoul 08826, Korea
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15
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Optoacoustic brain stimulation at submillimeter spatial precision. Nat Commun 2020; 11:881. [PMID: 32060282 PMCID: PMC7021819 DOI: 10.1038/s41467-020-14706-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 01/17/2020] [Indexed: 02/08/2023] Open
Abstract
Low-intensity ultrasound is an emerging modality for neuromodulation. Yet, transcranial neuromodulation using low-frequency piezo-based transducers offers poor spatial confinement of excitation volume, often bigger than a few millimeters in diameter. In addition, the bulky size limits their implementation in a wearable setting and prevents integration with other experimental modalities. Here, we report spatially confined optoacoustic neural stimulation through a miniaturized Fiber-Optoacoustic Converter (FOC). The FOC has a diameter of 600 μm and generates omnidirectional ultrasound wave locally at the fiber tip through the optoacoustic effect. We show that the acoustic wave generated by FOC can directly activate individual cultured neurons and generate intracellular Ca2+ transients. The FOC activates neurons within a radius of 500 μm around the fiber tip, delivering superior spatial resolution over conventional piezo-based low-frequency transducers. Finally, we demonstrate direct and spatially confined neural stimulation of mouse brain and modulation of motor activity in vivo. Low-intensity ultrasound can be used for neuromodulation in vivo, but it has poor spatial confinement and can result in unwanted cochlear pathway activation. Here the authors use the optoacoustic effect to generate spatially confined ultrasound waves to activate neurons within a 500 μm radius in the mouse brain.
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Rountree CM, Meng C, Troy JB, Saggere L. Mechanical Stimulation of the Retina: Therapeutic Feasibility and Cellular Mechanism. IEEE Trans Neural Syst Rehabil Eng 2019; 26:1075-1083. [PMID: 29752243 DOI: 10.1109/tnsre.2018.2822322] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Retinal prostheses that seek to restore vision by artificially stimulating retinal neurons with electrical current are an emerging treatment for photoreceptor degenerative diseases but face difficulties achieving naturalistic vision with high spatial resolution. Here, we report the unexpected discovery of a technique for mechanically stimulating retinal neurons with the potential to bypass the limitations of electrical stimulation. We found that pulsatile injections of standard Ames medium solution into explanted retinas of wild type rats under certain injection conditions (pulse-width > 50ms at 0.69 kPa pressure) elicit spatially localized retinal responses similar to light-evoked responses. The same injections made into photoreceptor degenerated retinas of transgenic S334ter-3 rats also elicit robust neural responses. We investigated the cellular mechanism causing these responses, by repeating the injections after treating the retinas with a pharmacological blocker of the transient receptor potential vanilloid (TRPV) channel group, a common mechanoreceptor found on retinal neurons, and observed a significant reduction in retinal ganglion cell spike rate response amplitudes. Together, these data reveal that therapeutic mechanical stimulation of the retina, occurring in part through TRPV channel activation, is feasible and this little explored neurostimulation paradigm could be useful in stimulating photoreceptor degenerated retinas for vision restoration.
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Jiang Q, Li G, Zhao H, Sheng W, Yue L, Su M, Weng S, Chan LLH, Zhou Q, Humayun MS, Qiu W, Zheng H. Temporal Neuromodulation of Retinal Ganglion Cells by Low-Frequency Focused Ultrasound Stimulation. IEEE Trans Neural Syst Rehabil Eng 2019; 26:969-976. [PMID: 29752231 DOI: 10.1109/tnsre.2018.2821194] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Significant progress has been made recently in treating neurological blindness using implantable visual prostheses. However, implantable medical devices are highly invasive and subject to many safety, efficacy, and cost issues. The discovery that ultrasound (US) may be useful as a noninvasive neuromodulation tool has aroused great interest in the field of acoustic retinal prostheses (ARPs). We have investigated the responsiveness of rat retinal ganglion cells (RGCs) to low-frequency focused US stimulation (LFUS) at 2.25 MHz and characterized the neurophysiological properties of US responses by performing in vitro multielectrode array recordings. The results show that LFUS can reliably activate RGCs. The US-induced responses did not correspond to the standard light responses and varied greatly among cell types. Moreover, dual-peak responses to US stimulation were observed that have not been reported previously. The temporal response properties of RGCs, including their latency, firing rate, and response type, were modulated by the acoustic intensity. These findings suggest the presence of a temporal neuromodulation effect of LFUS and potentially open a new avenue in the development of ARP.
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Gruenwald I, Spector A, Shultz T, Lischinsky D, Kimmel E. The beginning of a new era: treatment of erectile dysfunction by use of physical energies as an alternative to pharmaceuticals. Int J Impot Res 2019; 31:155-161. [DOI: 10.1038/s41443-019-0142-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 02/21/2019] [Indexed: 02/07/2023]
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Feng B, Chen L, Ilham SJ. A review on ultrasonic neuromodulation of the peripheral nervous system: enhanced or suppressed activities? APPLIED SCIENCES-BASEL 2019; 9. [PMID: 34113463 PMCID: PMC8188893 DOI: 10.3390/app9081637] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Ultrasonic (US) neuromodulation has emerged as a promising therapeutic means by delivering focused energy deep into the tissue. Low-intensity ultrasound (US) directly activates and/or inhibits neurons in the central nervous system (CNS). US neuromodulation of the peripheral nervous system (PNS) is less developed and rarely used clinically. Literature on the neuromodulatory effects of US on the PNS is controversy with some documenting enhanced neural activities, some showing suppressed activities, and others reporting mixed effects. US, with different range of intensity and strength, is likely to generate distinct physical effects in the stimulated neuronal tissues, which underlies different experimental outcomes in the literature. In this review, we summarize all the major reports that documented the effects of US on peripheral nerve endings, axons, and/or somata in the dorsal root ganglion. In particular, we thoroughly discuss the potential impacts by the following key parameters to the study outcomes of PNS neuromodulation by the US: frequency, pulse repetition frequency, duty cycle, intensity, metrics for peripheral neural activities, and type of biological preparations used in the studies. Potential mechanisms of peripheral US neuromodulation are summarized to provide a plausible interpretation to the seemly contradictory effects of enhanced and suppressed neural activities from US neuromodulation.
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Affiliation(s)
- Bin Feng
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
- Correspondence: ; Tel.: (001-860-486-6435)
| | - Longtu Chen
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - Sheikh J. Ilham
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
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A Novel Racing Array Transducer for Noninvasive Ultrasonic Retinal Stimulation: A Simulation Study. SENSORS 2019; 19:s19081825. [PMID: 30999576 PMCID: PMC6514975 DOI: 10.3390/s19081825] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/27/2019] [Accepted: 04/03/2019] [Indexed: 12/26/2022]
Abstract
Neurostimulation has proved to be an effective method for the restoration of visual perception lost due to retinal diseases. However, the clinically available retinal neurostimulation method is based on invasive electrodes, making it a high-cost and high-risk procedure. Recently, ultrasound has been demonstrated to be an effective way to achieve noninvasive neurostimulation. In this work, a novel racing array transducer with a contact lens shape is proposed for ultrasonic retinal stimulation. The transducer is flexible and placed outside the eyeball, similar to the application of a contact lens. Ultrasound emitted from the transducer can reach the retina without passing through the lens, thus greatly minimizing the acoustic absorption in the lens. The discretized Rayleigh–Sommerfeld method was employed for the acoustic field simulation, and patterned stimulation was achieved. A 5 MHz racing array transducer with different element numbers was simulated to optimize the array configuration. The results show that a 512-element racing array is the most appropriate configuration considering the necessary tradeoff between the element number and the stimulation resolution. The stimulation resolution at a focus of 24 mm is about 0.6 mm. The obtained results indicate that the proposed racing array design of the ultrasound transducer can improve the feasibility of an ultrasound retinal prosthesis.
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21
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Gibson BC, Sanguinetti JL, Badran BW, Yu AB, Klein EP, Abbott CC, Hansberger JT, Clark VP. Increased Excitability Induced in the Primary Motor Cortex by Transcranial Ultrasound Stimulation. Front Neurol 2018; 9:1007. [PMID: 30546342 PMCID: PMC6280333 DOI: 10.3389/fneur.2018.01007] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 11/07/2018] [Indexed: 12/29/2022] Open
Abstract
Background: Transcranial Ultrasound Stimulation (tUS) is an emerging technique that uses ultrasonic waves to noninvasively modulate brain activity. As with other forms of non-invasive brain stimulation (NIBS), tUS may be useful for altering cortical excitability and neuroplasticity for a variety of research and clinical applications. The effects of tUS on cortical excitability are still unclear, and further complications arise from the wide parameter space offered by various types of devices, transducer arrangements, and stimulation protocols. Diagnostic ultrasound imaging devices are safe, commonly available systems that may be useful for tUS. However, the feasibility of modifying brain activity with diagnostic tUS is currently unknown. Objective: We aimed to examine the effects of a commercial diagnostic tUS device using an imaging protocol on cortical excitability. We hypothesized that imaging tUS applied to motor cortex could induce changes in cortical excitability as measured using a transcranial magnetic stimulation (TMS) motor evoked potential (MEP) paradigm. Methods: Forty-three subjects were assigned to receive either verum (n = 21) or sham (n = 22) diagnostic tUS in a single-blind design. Baseline motor cortex excitability was measured using MEPs elicited by TMS. Diagnostic tUS was subsequently administered to the same cortical area for 2 min, immediately followed by repeated post-stimulation MEPs recorded up to 16 min post-stimulation. Results: Verum tUS increased excitability in the motor cortex (from baseline) by 33.7% immediately following tUS (p = 0.009), and 32.4% (p = 0.047) 6 min later, with excitability no longer significantly different from baseline by 11 min post-stimulation. By contrast, subjects receiving sham tUS showed no significant changes in MEP amplitude. Conclusion: These findings demonstrate that tUS delivered via a commercially available diagnostic imaging ultrasound system transiently increases excitability in the motor cortex as measured by MEPs. Diagnostic tUS devices are currently used for internal imaging in many health care settings, and the present results suggest that these same devices may also offer a promising tool for noninvasively modulating activity in the central nervous system. Further studies exploring the use of diagnostic imaging devices for neuromodulation are warranted.
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Affiliation(s)
- Benjamin C. Gibson
- Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, United States
| | - Joseph L. Sanguinetti
- Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, United States
- U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, United States
| | - Bashar W. Badran
- Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, United States
- U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, United States
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States
- Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South Carolina, Charleston, SC, United States
| | - Alfred B. Yu
- U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, United States
| | - Evan P. Klein
- Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, United States
| | - Christopher C. Abbott
- Department of Psychiatry, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | | | - Vincent P. Clark
- Psychology Clinical Neuroscience Center, Department of Psychology, University of New Mexico, Albuquerque, NM, United States
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, United States
- The Mind Research Network & LBERI, Albuquerque, NM, United States
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Qiu W, Zhou J, Chen Y, Su M, Li G, Zhao H, Gu X, Meng D, Wang C, Xiao Y, Lam KH, Dai J, Zheng H. A Portable Ultrasound System for Non-Invasive Ultrasonic Neuro-Stimulation. IEEE Trans Neural Syst Rehabil Eng 2018; 25:2509-2515. [PMID: 29220326 DOI: 10.1109/tnsre.2017.2765001] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Fundamental insights into the function of the neural circuits often follows from the advances in methodologies and tools for neuroscience. Electrode- and optical- based stimulation methods have been used widely for neuro-modulation with high resolution. However, they are suffering from inherent invasive surgical procedure. Ultrasound has been proved as a promising technology for neuro-stimulation in a non-invasive manner. However, no portable ultrasound system has been developed particularly for neuro-stimulation. The utilities used currently are assembled by traditional functional generator, power amplifier, and general transducer, therefore, resulting in lack of flexibility. This paper presents a portable system to achieve ultrasonic neuro-stimulation to satisfy various studies. The system incorporated a high voltage waveform generator and a matching circuit that were optimized for neuro-stimulation. A new switching mode power amplifier was designed and fabricated. The noise generated by the power amplifier was reduced (about 30 dB), and the size and weight were smaller in contrast with commercial equipment. In addition, a miniaturized ultrasound transducer was fabricated using Pb(Mg1/3Nb2/3)O3-PbTiO3(PMN-PT) 1-3 composite single crystal for the improved ultrasonic performance. The spatial peak temporal average pressure was higher than 250 kPa in the range of 0.5-5 MHz. In vitro and in vivo studies were conducted to show the performance of the system.
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23
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Ultrasonic modulation of neural circuit activity. Curr Opin Neurobiol 2018; 50:222-231. [PMID: 29674264 DOI: 10.1016/j.conb.2018.04.011] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 03/29/2018] [Accepted: 04/06/2018] [Indexed: 12/30/2022]
Abstract
Ultrasound (US) is recognized for its use in medical imaging as a diagnostic tool. As an acoustic energy source, US has become increasingly appreciated over the past decade for its ability to non-invasively modulate cellular activity including neuronal activity. Data obtained from a host of experimental models has shown that low-intensity US can reversibly modulate the physiological activity of neurons in peripheral nerves, spinal cord, and intact brain circuits. Experimental evidence indicates that acoustic pressures exerted by US act, in part, on mechanosensitive ion channels to modulate activity. While the precise mechanisms of action enabling US to both stimulate and suppress neuronal activity remain to be clarified, there are several advantages conferred by the physics of US that make it an appealing option for neuromodulation. For example, it can be focused with millimeter spatial resolutions through skull bone to deep-brain regions. By increasing our engineering capability to leverage such physical advantages while growing our understanding of how US affects neuronal function, the development of a new generation of non-invasive neurotechnology can be developed using ultrasonic methods.
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24
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Transcranial ultrasonic stimulation modulates single-neuron discharge in macaques performing an antisaccade task. Brain Stimul 2017; 10:1024-1031. [PMID: 28789857 DOI: 10.1016/j.brs.2017.07.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 07/15/2017] [Accepted: 07/19/2017] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Low intensity transcranial ultrasonic stimulation (TUS) has been demonstrated to non-invasively and transiently stimulate the nervous system. Although US neuromodulation has appeared robust in rodent studies, the effects of US in large mammals and humans have been modest at best. In addition, there is a lack of direct recordings from the stimulated neurons in response to US. Our study investigates the magnitude of the US effects on neuronal discharge in awake behaving monkeys and thus fills the void on both fronts. OBJECTIVE/HYPOTHESIS In this study, we demonstrate the feasibility of recording action potentials in the supplementary eye field (SEF) as TUS is applied simultaneously to the frontal eye field (FEF) in macaques performing an antisaccade task. RESULTS We show that compared to a control stimulation in the visual cortex, SEF activity is significantly modulated shortly after TUS onset. Among all cell types 40% of neurons significantly changed their activity after TUS. Half of the neurons showed a transient increase of activity induced by TUS. CONCLUSION Our study demonstrates that the neuromodulatory effects of non-invasive focused ultrasound can be assessed in real time in awake behaving monkeys by recording discharge activity from a brain region reciprocally connected with the stimulated region. The study opens the door for further parametric studies for fine-tuning the ultrasonic parameters. The ultrasonic effect could indeed be quantified based on the direct measurement of the intensity of the modulation induced on a single neuron in a freely performing animal. The technique should be readily reproducible in other primate laboratories studying brain function, both for exploratory and therapeutic purposes and to facilitate the development of future clinical TUS devices.
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25
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Baek H, Pahk KJ, Kim H. A review of low-intensity focused ultrasound for neuromodulation. Biomed Eng Lett 2017; 7:135-142. [PMID: 30603160 PMCID: PMC6208465 DOI: 10.1007/s13534-016-0007-y] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 11/05/2016] [Accepted: 11/16/2016] [Indexed: 12/14/2022] Open
Abstract
The ability of ultrasound to be focused into a small region of interest through the intact skull within the brain has led researchers to investigate its potential therapeutic uses for functional neurosurgery and tumor ablation. Studies have used high-intensity focused ultrasound to ablate tissue in localised brain regions for movement disorders and chronic pain while sparing the overlying and surrounding tissue. More recently, low-intensity focused ultrasound (LIFU) that induces reversible biological effects has been emerged as an alternative neuromodulation modality due to its bi-modal (i.e. excitation and suppression) capability with exquisite spatial specificity and depth penetration. Many compelling evidences of LIFU-mediated neuromodulatory effects including behavioral responses, electrophysiological recordings and functional imaging data have been found in the last decades. LIFU, therefore, has the enormous potential to improve the clinical outcomes as well as to replace the currently available neuromodulation techniques such as deep brain stimulation (DBS), transcranial magnetic stimulation and transcranial current stimulation. In this paper, we aim to provide a summary of pioneering studies in the field of ultrasonic neuromodulation including its underlying mechanisms that were published in the last 60 years. In closing, some of potential clinical applications of ultrasonic brain stimulation will be discussed.
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Affiliation(s)
- Hongchae Baek
- Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 02792 Republic of Korea
| | - Ki Joo Pahk
- Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 02792 Republic of Korea
| | - Hyungmin Kim
- Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 02792 Republic of Korea
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26
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Abstract
Recent advances in deep brain stimulators and brain-machine interfaces have greatly expanded the possibilities of neuroprosthetics and neuromodulation. Together with advances in neuroengineering, nanotechnology, molecular biology and material sciences, it is now possible to address fundamental questions in neuroscience in new, more powerful ways. It is now possible to apply these new technologies in ways that range from augmenting and restoring function to neuromodulation modalities that treat neuropsychiatric disorders. Recent developments in neuromodulation methods offer significant advantages and potential clinical benefits for a variety of disorders. Here we describe the current state of the art in neuromodulation methods, and some advances in brain-machine interfaces, describing the advantages and limitations of the clinical applications of each method. The future applications of these new methods and how they will shape the future of psychiatry and medicine, along with safety and ethical implications, are also discussed.
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Affiliation(s)
| | - Ricardo Ewbank Steffen
- Rio de Janeiro State University (UERJ), Institute of Social Medicine, Department of Health Policy and Management.
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Abstract
Ultrasound (US) is widely known for its utility as a biomedical imaging modality. An abundance of evidence has recently accumulated showing that US is also useful for non-invasively modulating brain circuit activity. Through a series of studies discussed in this short review, it has recently become recognized that transcranial focused ultrasound can exert mechanical (non-thermal) bioeffects on neurons and cells to produce focal changes in the activity of brain circuits. In addition to highlighting scientific breakthroughs and observations that have driven the development of the field of ultrasonic neuromodulation, this study also provides a discussion of mechanisms of action underlying the ability of ultrasound to physically stimulate and modulate brain circuit activity. Exemplifying some forward-looking tools that can be developed by integrating ultrasonic neuromodulation with other advanced acoustic technologies, some innovative acoustic imaging, beam forming, and focusing techniques are briefly reviewed. Finally, the future outlook for ultrasonic neuromodulation is discussed, specifically in the context of applications employing transcranial focused ultrasound for the investigation, diagnosis, and treatment of neuropsychiatric disorders.
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Affiliation(s)
- Maria Fini
- a School of Biological and Health Systems Engineering , Arizona State University , Tempe , AZ , USA
| | - William J Tyler
- a School of Biological and Health Systems Engineering , Arizona State University , Tempe , AZ , USA
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28
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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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29
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Cheng DL, Greenberg PB, Borton DA. Advances in Retinal Prosthetic Research: A Systematic Review of Engineering and Clinical Characteristics of Current Prosthetic Initiatives. Curr Eye Res 2017; 42:334-347. [PMID: 28362177 DOI: 10.1080/02713683.2016.1270326] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To date, reviews of retinal prostheses have focused primarily on devices undergoing human trials in the Western Hemisphere and fail to capture significant advances in materials and engineering research in countries such as Japan and Korea, as well as projects in early stages of development. To address these gaps, this systematic review examines worldwide advances in retinal prosthetic research, evaluates engineering characteristics and clinical progress of contemporary device initiatives, and identifies potential directions for future research in the field of retinal prosthetics. METHODS A literature search using PubMed, Google Scholar, and IEEExplore was conducted following the PRISMA Guidelines for Systematic Review. Inclusion criteria were peer-reviewed papers demonstrating progress in human or animal trials and papers discussing the prosthetic engineering design. For each initiative, a description of the device, its engineering considerations, and recent clinical results were provided. RESULTS Ten prosthetic initiatives met our inclusion criteria and were organized by stimulation location. Of these initiatives, four have recently completed human trials, three are undergoing multi- or single-center human trials, and three are undergoing preclinical animal testing. Only the Argus II (FDA 2013, CE 2011) has obtained FDA approval for use in the United States; the Alpha-IMS (CE 2013) has achieved the highest visual acuity using a Landolt-C test to date and is the only device presently undergoing a multicenter clinical trial. CONCLUSION Several distinct approaches to retinal stimulation have been successful in eliciting visual precepts in animals and/or humans. However, many clinical needs are still not met and engineering challenges must be addressed before a retinal prosthesis with the capability to fully and safely restore functional vision can be realized.
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Affiliation(s)
- Derrick L Cheng
- a Alpert Medical School , Brown University , Providence , RI , USA
| | - Paul B Greenberg
- b Section of Ophthalmology , Providence VA Medical Center , Providence , RI , USA.,c Division of Ophthalmology, Alpert Medical School , Brown University , Providence , RI , USA
| | - David A Borton
- d School of Engineering , Brown University , Providence , RI , USA.,e Brown Institute for Brain Science , Brown University , Providence , RI , USA
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Arens-Arad T, Farah N, Ben-Yaish S, Zlotnik A, Zalevsky Z, Mandel Y. Head mounted DMD based projection system for natural and prosthetic visual stimulation in freely moving rats. Sci Rep 2016; 6:34873. [PMID: 27731346 PMCID: PMC5059752 DOI: 10.1038/srep34873] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 09/19/2016] [Indexed: 02/04/2023] Open
Abstract
Novel technologies are constantly under development for vision restoration in blind patients. Many of these emerging technologies are based on the projection of high intensity light patterns at specific wavelengths, raising the need for the development of specialized projection systems. Here we present and characterize a novel projection system that meets the requirements for artificial retinal stimulation in rats and enables the recording of cortical responses. The system is based on a customized miniature Digital Mirror Device (DMD) for pattern projection, in both visible (525 nm) and NIR (915 nm) wavelengths, and a lens periscope for relaying the pattern directly onto the animal's retina. Thorough system characterization and the investigation of the effect of various parameters on obtained image quality were performed using ZEMAX. Simulation results revealed that images with an MTF higher than 0.8 were obtained with little effect of the vertex distance. Increased image quality was obtained at an optimal pupil diameter and smaller field of view. Visual cortex activity data was recorded simultaneously with pattern projection, further highlighting the importance of the system for prosthetic vision studies. This novel head mounted projection system may prove to be a vital tool in studying natural and artificial vision in behaving animals.
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Affiliation(s)
- Tamar Arens-Arad
- Faculty of Life Sciences, Optometry Track, Bar Ilan University, Ramat Gan, Israel
- Bar Ilan’s Institute for Nanotechnology and Advanced Materials (BINA), Bar Ilan University, Ramat Gan, Israel
| | - Nairouz Farah
- Faculty of Life Sciences, Optometry Track, Bar Ilan University, Ramat Gan, Israel
- Bar Ilan’s Institute for Nanotechnology and Advanced Materials (BINA), Bar Ilan University, Ramat Gan, Israel
| | - Shai Ben-Yaish
- Faculty of Engineering, Bar Ilan University, Ramat Gan, Israel
| | - Alex Zlotnik
- Faculty of Engineering, Bar Ilan University, Ramat Gan, Israel
| | - Zeev Zalevsky
- Bar Ilan’s Institute for Nanotechnology and Advanced Materials (BINA), Bar Ilan University, Ramat Gan, Israel
- Faculty of Engineering, Bar Ilan University, Ramat Gan, Israel
| | - Yossi Mandel
- Faculty of Life Sciences, Optometry Track, Bar Ilan University, Ramat Gan, Israel
- Bar Ilan’s Institute for Nanotechnology and Advanced Materials (BINA), Bar Ilan University, Ramat Gan, Israel
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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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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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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: 121] [Impact Index Per Article: 15.1] [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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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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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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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: 72] [Impact Index Per Article: 7.2] [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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Abstract
INTRODUCTION/BACKGROUND The Argus® II is the first retinal prosthesis approved for the treatment of patients blind from retinitis pigmentosa (RP), receiving CE (Conformité Européenne) marking in March 2011 and FDA approval in February 2013. Alpha-IMS followed closely and obtained CE marking in July 2013. Other devices are being developed, some of which are currently in clinical trials. SOURCES OF DATA A systematic literature search was conducted on PubMED, Google Scholar and IEEExplore. AREAS OF AGREEMENT Retinal prostheses play a part in restoring vision in blind RP patients providing stable, safe and long-term retinal stimulation. AREAS OF CONTROVERSY Objective improvement in visual function does not always translate into consistent improvement in the patient's quality of life. Controversy exists over the use of an external image-capturing device versus internally placed photodiode devices. GROWING POINTS The alpha-IMS, a photovoltaic-based retinal prosthesis recently obtained its CE marking in July 2013. AREAS TIMELY FOR DEVELOPING RESEARCH Improvement in retinal prosthetic vision depends on: (i) improving visual resolution, (ii) improving the visual field, (iii) developing an accurate neural code for image processing and (iv) improving the biocompatibility of the device to ensure longevity.
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Affiliation(s)
- Yvonne H-L Luo
- Biomedical Research Centre, National Institute of Health Research, Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London EC1V 2PD, UK
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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: 56] [Impact Index Per Article: 5.1] [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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Abstract
Focused ultrasound is a promising noninvasive technology for neural stimulation. Here we use the isolated salamander retina to characterize the effect of ultrasound on an intact neural circuit and compared these effects with those of visual stimulation of the same retinal ganglion cells. Ultrasound stimuli at an acoustic frequency of 43 MHz and a focal spot diameter of 90 μm delivered from a piezoelectric transducer evoked stable responses with a temporal precision equal to strong visual responses but with shorter latency. By presenting ultrasound and visual stimulation together, we found that ultrasonic stimulation rapidly modulated visual sensitivity but did not change visual temporal filtering. By combining pharmacology with ultrasound stimulation, we found that ultrasound did not directly activate retinal ganglion cells but did in part activate interneurons beyond photoreceptors. These results suggest that, under conditions of strong localized stimulation, timing variability is largely influenced by cells beyond photoreceptors. We conclude that ultrasonic stimulation is an effective and spatiotemporally precise method to activate the retina. Because the retina is the most accessible part of the CNS in vivo, ultrasonic stimulation may have diagnostic potential to probe remaining retinal function in cases of photoreceptor degeneration, and therapeutic potential for use in a retinal prosthesis. In addition, because of its noninvasive properties and spatiotemporal resolution, ultrasound neurostimulation promises to be a useful tool to understand dynamic activity in pharmacologically defined neural pathways in the retina.
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Yoo SS, Kim H, Filandrianos E, Taghados SJ, Park S. Non-invasive brain-to-brain interface (BBI): establishing functional links between two brains. PLoS One 2013; 8:e60410. [PMID: 23573251 PMCID: PMC3616031 DOI: 10.1371/journal.pone.0060410] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 02/26/2013] [Indexed: 02/02/2023] Open
Abstract
Transcranial focused ultrasound (FUS) is capable of modulating the neural activity of specific brain regions, with a potential role as a non-invasive computer-to-brain interface (CBI). In conjunction with the use of brain-to-computer interface (BCI) techniques that translate brain function to generate computer commands, we investigated the feasibility of using the FUS-based CBI to non-invasively establish a functional link between the brains of different species (i.e. human and Sprague-Dawley rat), thus creating a brain-to-brain interface (BBI). The implementation was aimed to non-invasively translate the human volunteer’s intention to stimulate a rat’s brain motor area that is responsible for the tail movement. The volunteer initiated the intention by looking at a strobe light flicker on a computer display, and the degree of synchronization in the electroencephalographic steady-state-visual-evoked-potentials (SSVEP) with respect to the strobe frequency was analyzed using a computer. Increased signal amplitude in the SSVEP, indicating the volunteer’s intention, triggered the delivery of a burst-mode FUS (350 kHz ultrasound frequency, tone burst duration of 0.5 ms, pulse repetition frequency of 1 kHz, given for 300 msec duration) to excite the motor area of an anesthetized rat transcranially. The successful excitation subsequently elicited the tail movement, which was detected by a motion sensor. The interface was achieved at 94.0±3.0% accuracy, with a time delay of 1.59±1.07 sec from the thought-initiation to the creation of the tail movement. Our results demonstrate the feasibility of a computer-mediated BBI that links central neural functions between two biological entities, which may confer unexplored opportunities in the study of neuroscience with potential implications for therapeutic applications.
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Affiliation(s)
- Seung-Schik Yoo
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
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