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Wang Q, Zhang Y, Xue H, Zeng Y, Lu G, Fan H, Jiang L, Wu J. Lead-free dual-frequency ultrasound implants for wireless, biphasic deep brain stimulation. Nat Commun 2024; 15:4017. [PMID: 38740759 DOI: 10.1038/s41467-024-48250-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 04/25/2024] [Indexed: 05/16/2024] Open
Abstract
Ultrasound-driven bioelectronics could offer a wireless scheme with sustainable power supply; however, current ultrasound implantable systems present critical challenges in biocompatibility and harvesting performance related to lead/lead-free piezoelectric materials and devices. Here, we report a lead-free dual-frequency ultrasound implants for wireless, biphasic deep brain stimulation, which integrates two developed lead-free sandwich porous 1-3-type piezoelectric composite elements with enhanced harvesting performance in a flexible printed circuit board. The implant is ultrasonically powered through a portable external dual-frequency transducer and generates programmable biphasic stimulus pulses in clinically relevant frequencies. Furthermore, we demonstrate ultrasound-driven implants for long-term biosafety therapy in deep brain stimulation through an epileptic rodent model. With biocompatibility and improved electrical performance, the lead-free materials and devices presented here could provide a promising platform for developing implantable ultrasonic electronics in the future.
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Affiliation(s)
- Qian Wang
- College of Materials Science and Engineering, Sichuan University, Chengdu, China
| | - Yusheng Zhang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, China
| | - Haoyue Xue
- College of Materials Science and Engineering, Sichuan University, Chengdu, China
| | - Yushun Zeng
- Alfred E. Mann Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Gengxi Lu
- Alfred E. Mann Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Hongsong Fan
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, China.
| | - Laiming Jiang
- College of Materials Science and Engineering, Sichuan University, Chengdu, China.
| | - Jiagang Wu
- College of Materials Science and Engineering, Sichuan University, Chengdu, China.
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Burton A, Wang Z, Song D, Tran S, Hanna J, Ahmad D, Bakall J, Clausen D, Anderson J, Peralta R, Sandepudi K, Benedetto A, Yang E, Basrai D, Miller LE, Tresch MC, Gutruf P. Fully implanted battery-free high power platform for chronic spinal and muscular functional electrical stimulation. Nat Commun 2023; 14:7887. [PMID: 38036552 PMCID: PMC10689769 DOI: 10.1038/s41467-023-43669-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 11/16/2023] [Indexed: 12/02/2023] Open
Abstract
Electrical stimulation of the neuromuscular system holds promise for both scientific and therapeutic biomedical applications. Supplying and maintaining the power necessary to drive stimulation chronically is a fundamental challenge in these applications, especially when high voltages or currents are required. Wireless systems, in which energy is supplied through near field power transfer, could eliminate complications caused by battery packs or external connections, but currently do not provide the harvested power and voltages required for applications such as muscle stimulation. Here, we introduce a passive resonator optimized power transfer design that overcomes these limitations, enabling voltage compliances of ± 20 V and power over 300 mW at device volumes of 0.2 cm2, thereby improving power transfer 500% over previous systems. We show that this improved performance enables multichannel, biphasic, current-controlled operation at clinically relevant voltage and current ranges with digital control and telemetry in freely behaving animals. Preliminary chronic results indicate that implanted devices remain operational over 6 weeks in both intact and spinal cord injured rats and are capable of producing fine control of spinal and muscle stimulation.
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Affiliation(s)
- Alex Burton
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Zhong Wang
- Department of Neuroscience, Northwestern University, Chicago, IL, 60611, USA
| | - Dan Song
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Sam Tran
- Department of Neuroscience, Northwestern University, Chicago, IL, 60611, USA
| | - Jessica Hanna
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Dhrubo Ahmad
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Jakob Bakall
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - David Clausen
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Jerry Anderson
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Roberto Peralta
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Kirtana Sandepudi
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Alex Benedetto
- Interdepartmental Neuroscience, Northwestern University, Chicago, IL, 60611, USA
| | - Ethan Yang
- Department of Neuroscience, Northwestern University, Chicago, IL, 60611, USA
| | - Diya Basrai
- Department of Neuroscience, Northwestern University, Chicago, IL, 60611, USA
| | - Lee E Miller
- Department of Neuroscience, Northwestern University, Chicago, IL, 60611, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
- Interdepartmental Neuroscience, Northwestern University, Chicago, IL, 60611, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, 60611, USA
| | - Matthew C Tresch
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA.
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, 60611, USA.
- Shirley Ryan AbilityLab, Chicago, IL, 60611, USA.
| | - Philipp Gutruf
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA.
- Bio5 Institute and Department of Neurology, University of Arizona, Tucson, AZ, 85721, USA.
- Department of Electrical and Computer Engineering, University of Arizona, Tucson, AZ, 85721, USA.
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Hsieh CC, Ker MD. Monopolar Biphasic Stimulator With Discharge Function and Negative Level Shifter for Neuromodulation SoC Integration in Low-Voltage CMOS Process. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2021; 15:568-579. [PMID: 34097616 DOI: 10.1109/tbcas.2021.3087036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A 16-channel monopolar biphasic stimulator chip with discharge function for biomedical applications is proposed and designed. To provide monopolar biphasic stimulus currents, the positive (6V) and the negative (-6V) voltage sources are supported to generate the desired current pulses of ±3 mA. The monopolar biphasic stimulator chip was fabricated in a 0.18-μm 1.8-V/3.3-V CMOS process with the common grounded p-type substrate. The overstress and reliability issues on the low-voltage transistors in the stimulator circuits were fully overcome by circuit design. The silicon area of each single channel only occupies 0.08 mm2 and the output level of stimulus current is up to ±3 mA. By applying the discharge function, safety concern of unbalanced charge in neuro-stimulation can be dealt properly. The residual average dc current is less than 3.42 nA after discharge is activated. Moreover, this chip has also been verified with both in-vitro imitation measurement and in-vivo animal test.
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Stamp MEM, Tong W, Ganesan K, Prawer S, Ibbotson MR, Garrett DJ. 3D Diamond Electrode Array for High-Acuity Stimulation in Neural Tissue. ACS APPLIED BIO MATERIALS 2020; 3:1544-1552. [DOI: 10.1021/acsabm.9b01165] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Melanie E. M. Stamp
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Wei Tong
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria 3053, Australia
- Department of Optometry and Vision Sciences, Melbourne School of Health Sciences, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Kumaravelu Ganesan
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Steven Prawer
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Michael R. Ibbotson
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria 3053, Australia
| | - David J. Garrett
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
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Tong W, Stamp M, Apollo NV, Ganesan K, Meffin H, Prawer S, Garrett DJ, Ibbotson MR. Improved visual acuity using a retinal implant and an optimized stimulation strategy. J Neural Eng 2019; 17:016018. [DOI: 10.1088/1741-2552/ab5299] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Spencer TC, Fallon JB, Shivdasani MN. Creating virtual electrodes with 2D current steering. J Neural Eng 2018; 15:035002. [DOI: 10.1088/1741-2552/aab1b8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Abdallah W, Li W, Weiland J, Humayun M, Ameri H. Implantation of multiple suprachoroidal electrode arrays in rabbits. J Curr Ophthalmol 2018; 30:68-73. [PMID: 29564412 PMCID: PMC5859463 DOI: 10.1016/j.joco.2017.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 11/06/2017] [Accepted: 11/10/2017] [Indexed: 11/23/2022] Open
Abstract
Purpose Epiretinal and subretinal prosthesis have been shown to be a valid way to provide some vision to patients with advanced outer retinal degeneration and profound vision loss. However, the field of vision for these patients is markedly limited by the area occupied by the electrode array. In this study, we aimed to evaluate the feasibility of implantation of multiple suprachoroidal electrode arrays in a single eye in order to increase the field of vision in patients implanted with retinal prosthesis. Methods The right eye of seventeen Dutch rabbits (age range, 5–6 months) was used for the study. Multiple inactive custom-made electrode arrays were inserted into the suprachoroidal space (SCS) and animals were followed up for up to 6 months using fundus photography, optical coherence tomography (OCT), and fluorescein angiography (FA). Results It was possible to surgically implant up to 8 electrode arrays in a single eye. None of the rabbits showed any major complications. The electrodes were well tolerated and remained in position in all rabbits. There was no evidence of retinal damage on follow-up exams and FA throughout the study. Conclusion Multiple suprachoroidal electrode array implantation is feasible and may provide a novel approach to increase the field of vision in subjects implanted with retinal prosthesis.
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Affiliation(s)
- Walid Abdallah
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Wen Li
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
| | - James Weiland
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Mark Humayun
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Hossein Ameri
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
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Jalligampala A, Sekhar S, Zrenner E, Rathbun DL. Optimal voltage stimulation parameters for network-mediated responses in wild type and rd10 mouse retinal ganglion cells. J Neural Eng 2017; 14:026004. [PMID: 28155848 DOI: 10.1088/1741-2552/14/2/026004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
To further improve the quality of visual percepts elicited by microelectronic retinal prosthetics, substantial efforts have been made to understand how retinal neurons respond to electrical stimulation. It is generally assumed that a sufficiently strong stimulus will recruit most retinal neurons. However, recent evidence has shown that the responses of some retinal neurons decrease with excessively strong stimuli (a non-monotonic response function). Therefore, it is necessary to identify stimuli that can be used to activate the majority of retinal neurons even when such non-monotonic cells are part of the neuronal population. Taking these non-monotonic responses into consideration, we establish the optimal voltage stimulation parameters (amplitude, duration, and polarity) for epiretinal stimulation of network-mediated (indirect) ganglion cell responses. We recorded responses from 3958 mouse retinal ganglion cells (RGCs) in both healthy (wild type, WT) and a degenerating (rd10) mouse model of retinitis pigmentosa-using flat-mounted retina on a microelectrode array. Rectangular monophasic voltage-controlled pulses were presented with varying voltage, duration, and polarity. We found that in 4-5 weeks old rd10 mice the RGC thresholds were comparable to those of WT. There was a marked response variability among mouse RGCs. To account for this variability, we interpolated the percentage of RGCs activated at each point in the voltage-polarity-duration stimulus space, thus identifying the optimal voltage-controlled pulse (-2.4 V, 0.88 ms). The identified optimal voltage pulse can activate at least 65% of potentially responsive RGCs in both mouse strains. Furthermore, this pulse is well within the range of stimuli demonstrated to be safe and effective for retinal implant patients. Such optimized stimuli and the underlying method used to identify them support a high yield of responsive RGCs and will serve as an effective guideline for future in vitro investigations of retinal electrostimulation by establishing standard stimuli for each unique experimental condition.
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Affiliation(s)
- Archana Jalligampala
- Institute for Ophthalmic Research, Eberhard Karls University, D-72076 Tübingen, Germany. Werner Reichardt Centre for Integrative Neuroscience (CIN), D-72076 Tübingen, Germany. Graduate Training Center of Neuroscience/International Max Planck Research School, D-72074 Tübingen, Germany
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Gerhardt M, Walz M, Beta C. Fluorescence Readout of a Patch Clamped Membrane by Laser Scanning Microscopy. Methods Mol Biol 2016; 1407:325-339. [PMID: 27271912 DOI: 10.1007/978-1-4939-3480-5_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this chapter, we describe how to shield a patch of a cell membrane against extracellularly applied chemoattractant stimuli. Classical patch clamp methodology is applied to allow for controlled shielding of a membrane patch by measuring the seal resistivity. In Dictyostelium cells, a seal resistivity of 50 MΩ proved to be tight enough to exclude molecules from diffusing into the shielded membrane region. This allowed for separating a shielded and a non-shielded region of a cell membrane to study the spatiotemporal dynamics of intracellular chemotactic signaling events at the interface between shielded and non-shielded areas. The spatiotemporal dynamics of signaling events in the membrane was read out by means of appropriate fluorescent markers using laser scanning confocal microscopy.
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Affiliation(s)
- Matthias Gerhardt
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476, Potsdam, Germany
| | - Michael Walz
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476, Potsdam, Germany
| | - Carsten Beta
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476, Potsdam, Germany.
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Gerhardt M, Walz M, Beta C. Signaling in chemotactic amoebae remains spatially confined to stimulated membrane regions. J Cell Sci 2014; 127:5115-25. [PMID: 25300796 DOI: 10.1242/jcs.161133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Recent work has demonstrated that the receptor-mediated signaling system in chemotactic amoeboid cells shows typical properties of an excitable system. Here, we delivered spatially confined stimuli of the chemoattractant cAMP to the membrane of differentiated Dictyostelium discoideum cells to investigate whether localized receptor stimuli can induce the spreading of excitable waves in the G-protein-dependent signal transduction system. By imaging the spatiotemporal dynamics of fluorescent markers for phosphatidylinositol (3,4,5)-trisphosphate (PIP₃), PTEN and filamentous actin, we observed that the activity of the signaling pathway remained spatially confined to the stimulated membrane region. Neighboring parts of the membrane were not excited and no receptor-initiated spatial spreading of excitation waves was observed. To generate localized cAMP stimuli, either particles that carried covalently bound cAMP molecules on their surface were brought into contact with the cell or a patch of the cell membrane was aspirated into a glass micropipette to shield this patch against freely diffusing cAMP molecules in the surrounding medium. Additionally, the binding site of the cAMP receptor was probed with different surface-immobilized cAMP molecules, confirming results from earlier ligand-binding studies.
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Affiliation(s)
- Matthias Gerhardt
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany
| | - Michael Walz
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany
| | - Carsten Beta
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany
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John SE, Shivdasani MN, Williams CE, Morley JW, Shepherd RK, Rathbone GD, Fallon JB. Suprachoroidal electrical stimulation: effects of stimulus pulse parameters on visual cortical responses. J Neural Eng 2013; 10:056011. [DOI: 10.1088/1741-2560/10/5/056011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Habib AG, Cameron MA, Suaning GJ, Lovell NH, Morley JW. Spatially restricted electrical activation of retinal ganglion cells in the rabbit retina by hexapolar electrode return configuration. J Neural Eng 2013; 10:036013. [DOI: 10.1088/1741-2560/10/3/036013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Habib AG, Cameron MA, Suaning GJ, Lovell NH, Morley JW. Efficacy of the hexpolar configuration in localizing the activation of retinal ganglion cells under electrical stimulation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:2776-9. [PMID: 23366501 DOI: 10.1109/embc.2012.6346540] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Retinal visual prostheses provide hope of restoring sight to patients suffering from retinal degeneration such as retinitis pigmentosa and age-related macular degeneration. Retinal prostheses are used to electrically stimulate residual neurons that are spared in these diseases, namely the retinal ganglion cells (RGCs), eliciting percepts of light termed 'phosphenes'. The elicitation of multiple phosphenes via an electrode array allows patterns to be produced, resulting in a rudimentary form of vision. For such patterns to be produced effectively, the prosthesis must generate well-defined phosphenes. To this end, the hexpolar configuration has been proposed as an alternative to the traditional monopolar or bipolar configurations. It utilizes six electrodes surrounding the stimulating electrode to serve as a combined return, or 'hex guard', purportedly localizing the activation to cells located within them. In this study, the efficacy of the hexpolar configuration in localizing activity was investigated by using patch-clamp electrophysiology to measure the activation thresholds of RGCs to electrical stimulation in isolated rabbit retina. Cells located outside the hex guard were found to have significantly higher relative hexpolar thresholds (>2 fold) as compared to cells located within the hex guard. This confirms the efficacy of the hexpolar configuration in localizing activity to within the hex guard. Furthermore, the effect of using cathodic-first versus anodic-first stimulation on hexpolar threshold and localization was investigated. No significant difference was observed between the two groups, in terms of lowering thresholds or improving localization.
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Affiliation(s)
- Amgad G Habib
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.
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Rattay F, Paredes L, Leao R. Strength-duration relationship for intra- versus extracellular stimulation with microelectrodes. Neuroscience 2012; 214:1-13. [PMID: 22516015 PMCID: PMC3401985 DOI: 10.1016/j.neuroscience.2012.04.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 03/06/2012] [Accepted: 04/05/2012] [Indexed: 12/04/2022]
Abstract
Chronaxie, a historically introduced excitability time parameter for electrical stimulation, has been assumed to be closely related to the time constant of the cell membrane. Therefore, it is perplexing that significantly larger chronaxies have been found for intracellular than for extracellular stimulation. Using compartmental model analysis, this controversy is explained on the basis that extracellular stimulation also generates hyperpolarized regions of the cell membrane hindering a steady excitation as seen in the intracellular case. The largest inside/outside chronaxie ratio for microelectrode stimulation is found in close vicinity of the cell. In the case of monophasic cathodic stimulation, the length of the primarily excited zone which is situated between the hyperpolarized regions increases with electrode-cell distance. For distant electrodes this results in an excitation process comparable to the temporal behavior of intracellular stimulation. Chronaxie also varies along the neural axis, being small for electrode positions at the nodes of Ranvier and axon initial segment and larger at the soma and dendrites. As spike initiation site can change for short and long pulses, in some cases strength-duration curves have a bimodal shape, and thus, they deviate from a classical monotonic curve as described by the formulas of Lapicque or Weiss.
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Affiliation(s)
- F. Rattay
- Institute for Analysis and Scientific Computing, Vienna University of Technology, A-1040 Vienna, Austria
| | - L.P. Paredes
- Institute for Analysis and Scientific Computing, Vienna University of Technology, A-1040 Vienna, Austria
| | - R.N. Leao
- Neurodynamics Laboratory, Department of Neuroscience, Uppsala University, Uppsala, Sweden
- Brain Institute, Federal University of Rio Grande do Norte, Natal-RN, Brazil
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Cicione R, Shivdasani MN, Fallon JB, Luu CD, Allen PJ, Rathbone GD, Shepherd RK, Williams CE. Visual cortex responses to suprachoroidal electrical stimulation of the retina: effects of electrode return configuration. J Neural Eng 2012; 9:036009. [PMID: 22595310 DOI: 10.1088/1741-2560/9/3/036009] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A clinically effective retinal prosthesis must evoke localized phosphenes in a retinotopic manner in response to stimulation of each of the retinal electrodes, evoke brightness cues over a wide dynamic range and function within safe stimulus limits. The effects of varying return configuration for retinal stimulation are currently unknown. To investigate this, we implanted a flexible, 7 × 12 electrode array into the suprachoroidal space of normally-sighted, anesthetized cats. Multi-unit activity in the primary visual cortex was recorded in response to electrical stimulation using various return configurations: monopolar vitreous (MPV), common ground (CG), hexagonal (HX), monopolar remote (MPR) and bipolar (BP_N). MPV stimulation was found to be the most charge efficient and was most likely to induce cortical activity within safe charge limits. HX and CG stimulation were found to exhibit greater retinal selectivity compared to the MPV return at the expense of lower cortical yield and higher P50 charge levels, while cortical selectivity was unaffected by choice of return. Responses using MPR and widely spaced BP_N configurations were similar to those using the MPV return. These results suggest that choice of return configuration for a retinal prosthesis will be balanced between resolution and stimulation within safe charge limits.
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