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Tsui CT, Mirkiani S, Roszko DA, Churchward MA, Mushahwar VK, Todd KG. In vitro biocompatibility evaluation of functional electrically stimulating microelectrodes on primary glia. Front Bioeng Biotechnol 2024; 12:1351087. [PMID: 38314352 PMCID: PMC10834782 DOI: 10.3389/fbioe.2024.1351087] [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: 12/06/2023] [Accepted: 01/10/2024] [Indexed: 02/06/2024] Open
Abstract
Neural interfacing devices interact with the central nervous system to alleviate functional deficits arising from disease or injury. This often entails the use of invasive microelectrode implants that elicit inflammatory responses from glial cells and leads to loss of device function. Previous work focused on improving implant biocompatibility by modifying electrode composition; here, we investigated the direct effects of electrical stimulation on glial cells at the electrode interface. A high-throughput in vitro system that assesses primary glial cell response to biphasic stimulation waveforms at 0 mA, 0.15 mA, and 1.5 mA was developed and optimized. Primary mixed glial cell cultures were generated from heterozygous CX3CR-1+/EGFP mice, electrically stimulated for 4 h/day over 3 days using 75 μm platinum-iridium microelectrodes, and biomarker immunofluorescence was measured. Electrodes were then imaged on a scanning electron microscope to assess sustained electrode damage. Fluorescence and electron microscopy analyses suggest varying degrees of localized responses for each biomarker assayed (Hoescht, EGFP, GFAP, and IL-1β), a result that expands on comparable in vivo models. This system allows for the comparison of a breadth of electrical stimulation parameters, and opens another avenue through which neural interfacing device developers can improve biocompatibility and longevity of electrodes in tissue.
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Affiliation(s)
- Christopher T. Tsui
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute (NMHI), University of Alberta, Edmonton, AB, Canada
- Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
| | - Soroush Mirkiani
- Neuroscience and Mental Health Institute (NMHI), University of Alberta, Edmonton, AB, Canada
- Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
| | - David A. Roszko
- Neuroscience and Mental Health Institute (NMHI), University of Alberta, Edmonton, AB, Canada
- Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
| | - Matthew A. Churchward
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute (NMHI), University of Alberta, Edmonton, AB, Canada
- Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
- Department of Biological and Environmental Sciences, Concordia University of Edmonton, Edmonton, AB, Canada
| | - Vivian K. Mushahwar
- Neuroscience and Mental Health Institute (NMHI), University of Alberta, Edmonton, AB, Canada
- Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
- Division of Physical Medicine and Rehabilitation, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Kathryn G. Todd
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute (NMHI), University of Alberta, Edmonton, AB, Canada
- Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
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Boogers A, Peeters J, Van Bogaert T, De Vloo P, Vandenberghe W, Nuttin B, Mc Laughlin M. Interphase Gaps in Symmetric Biphasic Pulses Reduce the Therapeutic Window in Ventral Intermediate Nucleus of the Thalamus-Deep Brain Stimulation for Essential Tremor. Neuromodulation 2023; 26:1699-1704. [PMID: 36404213 DOI: 10.1016/j.neurom.2022.09.012] [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] [Received: 07/05/2022] [Revised: 08/23/2022] [Accepted: 09/13/2022] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Symmetric biphasic pulses enlarge the therapeutic window in thalamic deep brain stimulation in patients with essential tremor. Adding an interphase gap to these symmetric biphasic pulses may further affect the therapeutic window. MATERIALS AND METHODS Nine patients (16 hemispheres) were included in this study. Biphasic pulses (anodic phase first) with interphase gaps of 0, 10, 20, 50, and 100 μs were tested, in random order. The outcome parameters were the therapeutic threshold (TT) and side-effect threshold (SET), and thus also the therapeutic window (TW). RESULTS Increasing interphase gaps lowered both SET and TT (linear mixed-effects model; p < 0.001 and p < 0.001). Because SET decreased predominantly, increasing interphase gaps resulted in smaller TWs (linear mixed-effects model; p < 0.001). DISCUSSION AND CONCLUSIONS Introducing an interphase gap in a symmetric biphasic pulse may lead to less selectivity in fiber or neuronal activation. Our findings show that, in the context of anode-first biphasic pulses, the use of zero-interphase gaps results in the largest TW. CLINICAL TRIAL REGISTRATION The Clinicaltrials.gov registration number for the study is NCT05177900.
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Affiliation(s)
- Alexandra Boogers
- Exp ORL, Department of Neurosciences, the Leuven Brain Institute, KU Leuven, Leuven, Belgium; Department of Neurology, UZ Leuven, Leuven, Belgium.
| | - Jana Peeters
- Exp ORL, Department of Neurosciences, the Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Tine Van Bogaert
- Exp ORL, Department of Neurosciences, the Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Philippe De Vloo
- Department of Neurosurgery, UZ Leuven, Leuven, Belgium; Experimental Neurosurgery and Neuroanatomy, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Wim Vandenberghe
- Department of Neurology, UZ Leuven, Leuven, Belgium; Laboratory for Parkinson Research, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Bart Nuttin
- Department of Neurosurgery, UZ Leuven, Leuven, Belgium; Experimental Neurosurgery and Neuroanatomy, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Myles Mc Laughlin
- Exp ORL, Department of Neurosciences, the Leuven Brain Institute, KU Leuven, Leuven, Belgium.
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Hu Y, Feng Z, Zheng L, Ye X. Interactions between cathodic- and anodic-pulses during high-frequency stimulations with the monophasic-pulses alternating in polarity at axons-experiment and simulation studies. J Neural Eng 2023; 20:056021. [PMID: 37703869 DOI: 10.1088/1741-2552/acf959] [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] [Received: 04/30/2023] [Accepted: 09/13/2023] [Indexed: 09/15/2023]
Abstract
Background. Electrical neuromodulation therapies commonly utilize high-frequency stimulations (HFS) of biphasic-pulses to treat neurological disorders. The biphasic pulse consists of a leading cathodic-phase to activate neurons and a lagging anodic-phase to balance electrical charges. Because both monophasic cathodic- and anodic-pulses can depolarize neuronal membranes, splitting biphasic-pulses into alternate cathodic- and anodic-pulses could be a feasible strategy to improve stimulation efficiency.Objective. We speculated that neurons in the volume initially activated by both polarity pulses could change to be activated only by anodic-pulses during sustained HFS of alternate monophasic-pulses. To verify the hypothesis, we investigated the interactions of the monophasic pulses during HFS and revealed possible underlying mechanisms.Approach. Different types of pulse stimulations were applied at the alvear fibers (i.e. the axons of CA1 pyramidal neurons) to antidromically activate the neuronal cell bodies in the hippocampal CA1 region of anesthetized ratsin-vivo. Sequences of antidromic HFS (A-HFS) were applied with alternate monophasic-pulses or biphasic-pulses. The pulse frequency in the A-HFS sequences was 50 or 100 Hz. The A-HFS duration was 120 s. The amplitude of antidromically-evoked population spike was measured to evaluate the neuronal firing induced by each pulse. A computational model of axon was used to explore the possible mechanisms of neuronal modulations. The changes of model variables during sustained A-HFS were analyzed.Main results. In rat experiments, with a same pulse intensity, the activation volume of a cathodic-pulse was greater than that of an anodic-pulse. In paired-pulse tests, a preceding cathodic-pulse was able to prevent a following anodic-pulse from activating neurons due to refractory period. This indicated that the activation volume of a cathodic-pulse covered that of an anodic-pulse. However, during sustained A-HFS of alternate monophasic-pulses, the anodic-pulses were able to prevail over the cathodic-pulses in activating neurons in the overlapped activation volume. Model simulation results show the mechanisms of the activation failures of cathodic-pulses. They include the excessive membrane depolarization caused by an accumulation of potassium ions, the obstacle of hyperpolarization in the conduction pathway and the interactions from anodic-pulses.Significance. The study firstly showed the domination of anodic-pulses over cathodic-pulses in their competitions to activate neurons during sustained HFS. The finding provides new clues for designing HFS paradigms to improve the efficiency of neuromodulation therapies.
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Affiliation(s)
- Yifan Hu
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Zhouyan Feng
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Lvpiao Zheng
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Xiangyu Ye
- Key Laboratory of Biomedical Engineering for Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
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Gilbert Z, Mason X, Sebastian R, Tang AM, Martin Del Campo-Vera R, Chen KH, Leonor A, Shao A, Tabarsi E, Chung R, Sundaram S, Kammen A, Cavaleri J, Gogia AS, Heck C, Nune G, Liu CY, Kellis SS, Lee B. A review of neurophysiological effects and efficiency of waveform parameters in deep brain stimulation. Clin Neurophysiol 2023; 152:93-111. [PMID: 37208270 DOI: 10.1016/j.clinph.2023.04.007] [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: 09/20/2022] [Revised: 02/09/2023] [Accepted: 04/15/2023] [Indexed: 05/21/2023]
Abstract
Neurostimulation has diverse clinical applications and potential as a treatment for medically refractory movement disorders, epilepsy, and other neurological disorders. However, the parameters used to program electrodes-polarity, pulse width, amplitude, and frequency-and how they are adjusted have remained largely untouched since the 1970 s. This review summarizes the state-of-the-art in Deep Brain Stimulation (DBS) and highlights the need for further research to uncover the physiological mechanisms of neurostimulation. We focus on studies that reveal the potential for clinicians to use waveform parameters to selectively stimulate neural tissue for therapeutic benefit, while avoiding activating tissue associated with adverse effects. DBS uses cathodic monophasic rectangular pulses with passive recharging in clinical practice to treat neurological conditions such as Parkinson's Disease. However, research has shown that stimulation efficiency can be improved, and side effects reduced, through modulating parameters and adding novel waveform properties. These developments can prolong implantable pulse generator lifespan, reducing costs and surgery-associated risks. Waveform parameters can stimulate neurons based on axon orientation and intrinsic structural properties, providing clinicians with more precise targeting of neural pathways. These findings could expand the spectrum of diseases treatable with neuromodulation and improve patient outcomes.
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Affiliation(s)
- Zachary Gilbert
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States.
| | - Xenos Mason
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States; USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, United States
| | - Rinu Sebastian
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Austin M Tang
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Roberto Martin Del Campo-Vera
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Kuang-Hsuan Chen
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Andrea Leonor
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Arthur Shao
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Emiliano Tabarsi
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Ryan Chung
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Shivani Sundaram
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Alexandra Kammen
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Jonathan Cavaleri
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Angad S Gogia
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Christi Heck
- Department of Neurology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States; USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, United States
| | - George Nune
- Department of Neurology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States; USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, United States
| | - Charles Y Liu
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States; Department of Neurology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States; USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, United States
| | - Spencer S Kellis
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States; USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, United States
| | - Brian Lee
- Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States; USC Neurorestoration Center, Keck School of Medicine of USC, Los Angeles, CA, United States
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Xu A, Beyeler M. Retinal ganglion cells undergo cell type-specific functional changes in a computational model of cone-mediated retinal degeneration. Front Neurosci 2023; 17:1147729. [PMID: 37274203 PMCID: PMC10233015 DOI: 10.3389/fnins.2023.1147729] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/02/2023] [Indexed: 06/06/2023] Open
Abstract
Introduction Understanding the retina in health and disease is a key issue for neuroscience and neuroengineering applications such as retinal prostheses. During degeneration, the retinal network undergoes complex and multi-stage neuroanatomical alterations, which drastically impact the retinal ganglion cell (RGC) response and are of clinical importance. Here we present a biophysically detailed in silico model of the cone pathway in the retina that simulates the network-level response to both light and electrical stimulation. Methods The model included 11, 138 cells belonging to nine different cell types (cone photoreceptors, horizontal cells, ON/OFF bipolar cells, ON/OFF amacrine cells, and ON/OFF ganglion cells) confined to a 300 × 300 × 210μm patch of the parafoveal retina. After verifying that the model reproduced seminal findings about the light response of retinal ganglion cells (RGCs), we systematically introduced anatomical and neurophysiological changes (e.g., reduced light sensitivity of photoreceptor, cell death, cell migration) to the network and studied their effect on network activity. Results The model was not only able to reproduce common findings about RGC activity in the degenerated retina, such as hyperactivity and increased electrical thresholds, but also offers testable predictions about the underlying neuroanatomical mechanisms. Discussion Overall, our findings demonstrate how biophysical changes typified by cone-mediated retinal degeneration may impact retinal responses to light and electrical stimulation. These insights may further our understanding of retinal processing and inform the design of retinal prostheses.
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Affiliation(s)
- Aiwen Xu
- Department of Computer Science, University of California, California, Santa Barbara, CA, United States
| | - Michael Beyeler
- Department of Computer Science, University of California, California, Santa Barbara, CA, United States
- Department of Psychological & Brain Sciences, University of California, California, Santa Barbara, CA, United States
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Makino D, Ueki A, Matsumoto H, Nagamine K. Minimally invasive current-controlled electrical stimulation system for bacteria using highly capacitive conducting polymer-modified electrodes. Bioelectrochemistry 2023; 149:108290. [DOI: 10.1016/j.bioelechem.2022.108290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/04/2022] [Accepted: 10/07/2022] [Indexed: 11/07/2022]
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Xu A, Beyeler M. Retinal ganglion cells undergo cell typeâ€"specific functional changes in a biophysically detailed model of retinal degeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.13.523982. [PMID: 36711897 PMCID: PMC9882163 DOI: 10.1101/2023.01.13.523982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Understanding the retina in health and disease is a key issue for neuroscience and neuroengineering applications such as retinal prostheses. During degeneration, the retinal network undergoes complex and multi-stage neuroanatomical alterations, which drastically impact the retinal ganglion cell (RGC) response and are of clinical importance. Here we present a biophysically detailed in silico model of retinal degeneration that simulates the network-level response to both light and electrical stimulation as a function of disease progression. The model is not only able to reproduce common findings about RGC activity in the degenerated retina, such as hyperactivity and increased electrical thresholds, but also offers testable predictions about the underlying neuroanatomical mechanisms. Overall, our findings demonstrate how biophysical changes associated with retinal degeneration affect retinal responses to both light and electrical stimulation, which may further our understanding of visual processing in the retina as well as inform the design and application of retinal prostheses.
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Li W, Haji Ghaffari D, Misra R, Weiland JD. Retinal ganglion cell desensitization is mitigated by varying parameter constant excitation pulse trains. Front Cell Neurosci 2022; 16:897146. [PMID: 36035262 PMCID: PMC9407683 DOI: 10.3389/fncel.2022.897146] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 07/15/2022] [Indexed: 11/20/2022] Open
Abstract
Retinal prostheses partially restore vision in patients blinded by retinitis pigmentosa (RP) and age-related macular degeneration (AMD). One issue that limits the effectiveness of retinal stimulation is the desensitization of the retina response to repeated pulses. Rapid fading of percepts is reported in clinical studies. We studied the retinal output evoked by fixed pulse trains vs. pulse trains that have variable parameters pulse-to-pulse. We used the current clamp to record RGC spiking in the isolated mouse retina. Trains of biphasic current pulses at different frequencies and amplitudes were applied. The main results we report are: (1) RGC desensitization was induced by increasing stimulus frequency, but was unrelated to stimulus amplitude. Desensitization persisted when the 20 Hz stimulation pulses were applied to the retinal ganglion cells at 65 μA, 85 μA, and 105 μA. Subsequent pulses in the train evoked fewer spikes. There was no obvious desensitization when 2 Hz stimulation pulse trains were applied. (2) Blocking inhibitory GABAA receptor increased spontaneous activity but did not reduce desensitization. (3) Pulse trains with constant charge or excitation (based on strength-duration curves) but varying pulse width, amplitude, and shape increased the number of evoked spikes/pulse throughout the pulse train. This suggests that retinal desensitization can be partially overcome by introducing variability into each pulse.
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Affiliation(s)
- Wennan Li
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Dorsa Haji Ghaffari
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Rohit Misra
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - James D. Weiland
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
- *Correspondence: James D. Weiland
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Zheng L, Feng Z, Xu Y, Yuan Y, Hu Y. An Anodic Phase Can Facilitate Rather Than Weaken a Cathodic Phase to Activate Neurons in Biphasic-Pulse Axonal Stimulations. Front Neurosci 2022; 16:823423. [PMID: 35368280 PMCID: PMC8968170 DOI: 10.3389/fnins.2022.823423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 02/01/2022] [Indexed: 11/13/2022] Open
Abstract
Electrical pulses have been promisingly utilized in neural stimulations to treat various diseases. Usually, charge-balanced biphasic pulses are applied in the clinic to eliminate the possible side effects caused by charge accumulations. Because of its reversal action to the preceding cathodic phase, the subsequent anodic phase has been commonly considered to lower the activation efficiency of biphasic pulses. However, an anodic pulse itself can also activate axons with its “virtual cathode” effect. Therefore, we hypothesized that the anodic phase of a biphasic pulse could facilitate neuronal activation in some circumstances. To verify the hypothesis, we compared the activation efficiencies of cathodic pulse, biphasic pulse, and anodic pulse applied in both monopolar and bipolar modes in the axonal stimulation of alveus in rat hippocampal CA1 region in vivo. The antidromically evoked population spikes (APS) were recorded and used to evaluate the amount of integrated firing of pyramidal neurons induced by pulse stimulations. We also used a computational model to investigate the pulse effects on axons at various distances from the stimulation electrode. The experimental results showed that, with a small pulse intensity, a cathodic pulse recruited more neurons to fire than a biphasic pulse. However, the situation was reversed with an increased pulse intensity. In addition, setting an inter-phase gap of 100 μs was able to increase the activation efficiency of a biphasic pulse to exceed a cathodic pulse even with a relatively small pulse intensity. Furthermore, the latency of APS evoked by a cathodic pulse was always longer than that of APS evoked by a biphasic pulse, indicating different initial sites of the neuronal firing evoked by the different types of pulses. The computational results of axon modeling showed that the subsequent anodic phase was able to relieve the hyperpolarization block in the flanking regions generated by the preceding cathodic phase, thereby increasing rather than decreasing the activation efficiency of a biphasic pulse with a relatively great intensity. These results of both rat experiments and computational modeling firstly reveal a facilitation rather than an attenuation effect of the anodic phase on biphasic-pulse stimulations, which provides important information for designing electrical stimulations for neural therapies.
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Paknahad J, Humayun M, Lazzi G. Selective Activation of Retinal Ganglion Cell Subtypes Through Targeted Electrical Stimulation Parameters. IEEE Trans Neural Syst Rehabil Eng 2022; 30:350-359. [PMID: 35130164 PMCID: PMC8904155 DOI: 10.1109/tnsre.2022.3149967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To restore vision to the low vision, epiretinal implants have been developed to electrically stimulate the healthy retinal ganglion cells (RGCs) in the degenerate retina. Given the diversity of retinal ganglion cells as well as the difference in their visual function, selective activation of RGCs subtypes can significantly improve the quality of the restored vision. Our recent results demonstrated that with the proper modulation of the current amplitude, small D1-bistratified cells with the contribution to blue/yellow color opponent pathway can be selectively activated at high frequency (200 Hz). The computational results correlated with the clinical findings revealing the blue sensation of 5/7 subjects with epiretinal implants at high frequency. Here we further explored the impacts of alterations in pulse duration and interphase gap on the response of RGCs at high frequency. We used the developed RGCs, A2-monostratified and D1-bistratified, and examined their response to a range of pulse durations (0.1−1.2 ms) and interphase gaps (0−1 ms). We found that the use of short pulse durations with no interphase gap at high frequency increases the differential response of RGCs, offering better opportunities for selective activation of D1 cells. The presence of the interphase gap has shown to reduce the overall differential response of RGCs. We also explored how the low density of calcium channels enhances the responsiveness of RGCs at high frequency.
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Krishnan A, Forssell M, Du Z, Cui XT, Fedder GK, Kelly SK. Residual voltage as an ad-hoc indicator of electrode damage in biphasic electrical stimulation. J Neural Eng 2021; 18. [PMID: 34400592 DOI: 10.1088/1741-2552/ac028a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 05/18/2021] [Indexed: 11/12/2022]
Abstract
Objective.We derive and demonstrate how residual voltage (RV) from a biphasic electrical stimulation pulse can be used to recognize degradation at the electrode-tissue interface.Approach.Using a first order model of the electrode-tissue interface and a rectangular biphasic stimulation current waveform, we derive the equations for RV as well as RV growth over several stimulation pulses. To demonstrate the use of RV for damage detection, we simulate accelerated damage on sputtered iridium oxide film (SIROF) electrodes using potential cycling. RV measurements of the degraded electrodes are compared against standard characterization methods of cyclic voltammetry and electrochemical impedance spectroscopy.Main results.Our theoretical discussion illustrates how an intrinsic RV arises even from perfectly balanced biphasic pulses due to leakage via the charge-transfer resistance. Preliminary data inin-vivorat experiments follow the derived model of RV growth, thereby validating our hypothesis that RV is a characteristic of the electrode-tissue interface. RV can therefore be utilized for detecting damage at the electrode. Our experimental results for damage detection show that delamination of SIROF electrodes causes a reduction in charge storage capacity, which in turn reflects a measurable increase in RV.Significance.Chronically implanted electrical stimulation systems with multi-electrode arrays have been the focus of physiological engineering research for the last decade. Changes in RV over time can be a quick and effective method to identify and disconnect faulty electrodes in large arrays. Timely diagnoses of electrode status can ensure optimal long term operation, and prevent further damage to the tissue near these electrodes.
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Affiliation(s)
- Ashwati Krishnan
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
| | - Mats Forssell
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
| | - Zhanhong Du
- Shenzhen Institute of Advanced Technology, Shenzhen City, Guangdong, People's Republic of China
| | - X Tracy Cui
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, United States of America
| | - Gary K Fedder
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
| | - Shawn K Kelly
- VA, Pittsburgh, PA 15240, United States of America.,Institute of Complex Engineered Systems, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
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Different effects of monophasic pulses and biphasic pulses applied by a bipolar stimulation electrode in the rat hippocampal CA1 region. Biomed Eng Online 2021; 20:25. [PMID: 33750406 PMCID: PMC7942171 DOI: 10.1186/s12938-021-00862-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 03/01/2021] [Indexed: 11/10/2022] Open
Abstract
Background Electrical pulse stimulations have been applied in brain for treating certain diseases such as movement disorders. High-frequency stimulations (HFS) of biphasic pulses have been used in clinic stimulations, such as deep brain stimulation (DBS), to minimize the risk of tissue damages caused by the electrical stimulations. However, HFS sequences of monophasic pulses have often been used in animal experiments for studying neuronal responses to the stimulations. It is not clear yet what the differences of the neuronal responses to the HFS of monophasic pulses from the HFS of biphasic pulses are. Methods To investigate the neuronal responses to the two types of pulses, orthodromic-HFS (O-HFS) and antidromic-HFS (A-HFS) of biphasic and monophasic pulses (1-min) were delivered by bipolar electrodes, respectively, to the Schaffer collaterals (i.e., afferent fibers) and the alveus fibers (i.e., efferent fibers) of the rat hippocampal CA1 region in vivo. Evoked population spikes of CA1 pyramidal neurons to the HFSs were recorded in the CA1 region. In addition, single pulses of antidromic- and orthodromic-test stimuli were applied before and after HFSs to evaluate the baseline and the recovery of neuronal activity, respectively. Results Spreading depression (SD) appeared during sequences of 200-Hz monophasic O-HFS with a high incidence (4/5), but did not appear during corresponding 200-Hz biphasic O-HFS (0/6). A preceding burst of population spikes appeared before the SD waveforms. Then, the SD propagated slowly, silenced neuronal firing temporarily and resulted in partial recovery of orthodromically evoked population spikes (OPS) after the end of O-HFS. No SD events appeared during the O-HFS with a lower frequency of 100 Hz of monophasic or biphasic pulses (0/5 and 0/6, respectively), neither during the A-HFS of 200-Hz pulses (0/9). The antidromically evoked population spikes (APS) after 200-Hz biphasic A-HFS recovered to baseline level within ~ 2 min. However, the APS only recovered partially after the 200-Hz A-HFS of monophasic pulses. Conclusions The O-HFS with a higher frequency of monophasic pulses can induce the abnormal neuron activity of SD and the A-HFS of monophasic pulses can cause a persisting attenuation of neuronal excitability, indicating neuronal damages caused by monophasic stimulations in brain tissues. The results provide guidance for proper stimulation protocols in clinic and animal experiments.
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Eickhoff S, Jarvis JC. Pulse Shaping Strategies for Electroceuticals: A Comprehensive Survey of the Use of Interphase Gaps in Miniature Stimulation Systems. IEEE Trans Biomed Eng 2021; 68:1658-1667. [PMID: 33651679 DOI: 10.1109/tbme.2021.3063029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Interphase gaps (IPGs) are among the most commonly suggested pulse shape variations to try to enhance neural stimulation efficiency by reducing the action potential (AP) suppressing effect of an early anodic hyperpolarization. The majority of published literature on the effect of IPGs is based on investigations of monopolar stimulation configurations. However, many contemporary neuromodulation applications including the emerging field of electroceutical devices operate in a bipolar electrode configuration. METHODS We investigated the effect of IPGs and asymmetric biphasic current controlled pulses with reduced anodic amplitude on neural activation in both principal electrode configurations in a rodent in-vivo nerve muscle preparation. RESULTS In the monopolar electrode configuration, our findings of 10.9 ± 1.5% decreased stimulation amplitude with 200 μs IPGs in biphasic pulses of 40 μs phase width are in agreement with published literature in this configuration. Surprisingly, using the bipolar configuration, opposite effects of IPGs were observed and neural activation required up to 18.6 ± 3.1% (phase width 100 μs, IPG = 1000 μs) higher amplitudes. Electroneurogram recordings of the stimulated nerve revealed temporal differences in AP generation between the monopolar and bipolar configuration. In the bipolar configuration excitation first occurred in response to the middle field transition of biphasic pulses. CONCLUSION This is the first study to report consistently increased amplitude requirements with IPGs in bipolar stimulation configurations. SIGNIFICANCE Our findings must be taken into consideration when designing stimulation waveforms for neuromodulation devices that operate in a bipolar mode to avoid increased amplitude requirements that result in increased energy consumption.
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Haji Ghaffari D, Finn KE, Jeganathan VSE, Patel U, Wuyyuru V, Roy A, Weiland JD. The effect of waveform asymmetry on perception with epiretinal prostheses. J Neural Eng 2020; 17:045009. [PMID: 32590371 DOI: 10.1088/1741-2552/aba07e] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Objective Retinal prosthetic implants have helped improve vision in patients blinded by photoreceptor degeneration. Retinal implant users report improvements in light perception and performing visual tasks, but their ability to perceive shapes and letters is limited due to the low precision of retinal activation, which is exacerbated by axonal stimulation and high perceptual thresholds. A previous in vitro study in our lab used calcium imaging to measure the spatial activity of mouse retinal ganglion cells (RGCs) in response to electrical stimulation. Based on this study, symmetric anodic-first (SA) stimulation effectively avoided axonal activation and asymmetric anodic-first stimulation (AA) with duration ratios (ratio of the anodic to cathodic phase) greater than 10 reduced RGC activation thresholds significantly. Applying these novel stimulation strategies in clinic may increase perception precision and improve the overall patient outcomes. Approach We combined human subject testing and computational modeling to further examine the effect of SA and AA stimuli on perception shapes and thresholds for epiretinal stimulation of RGCs. Main results Threshold measurement in three Argus II participants indicated that AA stimulation could increase perception probabilities compared to a standard symmetric cathodic-first (SC) pulse, and this effect can be intensified by addition of an interphae gap (IPG). Our in silico RGC model predicts lower thresholds with AA and asymmetric cathodic-first (AC) stimuli compared to a SC pulse. This effect was more pronounced at shorter pulse widths. The most effective pulse for threshold reduction with short pulse durations (≤0.12 ms) was AA stimulation with small duration ratios (≤5) and long IPGs (≥2 ms). For the 0.5 ms pulse duration, SC stimulation with IPGs longer than 0.5 ms, or asymmetric stimuli with large duration ratios (≥20) were most effective in threshold reduction. Phosphene shape analysis did not reveal a significant change in percept elongation with SA stimulation. However, there was a significant increase in percept size (P < 0.01) with AA stimulation compared to the standard pulse in one participant. Significane Including asymmetric waveform capability will provide more flexible options for optimization and personalized fitting of retinal implants.
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Affiliation(s)
- Dorsa Haji Ghaffari
- Department of Biomedical Engineering, Michigan Engineering, University of Michigan, Ann Arbor, MI 48109, United States of America. Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, United States of America
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15
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Kosta P, Loizos K, Lazzi G. Stimulus waveform design for decreasing charge and increasing stimulation selectivity in retinal prostheses. Healthc Technol Lett 2020; 7:66-71. [PMID: 32754340 PMCID: PMC7353818 DOI: 10.1049/htl.2019.0115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 05/04/2020] [Accepted: 05/12/2020] [Indexed: 02/03/2023] Open
Abstract
Retinal degenerative diseases, such as retinitis pigmentosa, begin with damage to the photoreceptor layer of the retina. In the absence of presynaptic input from photoreceptors, networks of electrically coupled AII amacrine and cone bipolar cells have been observed to exhibit oscillatory behaviour and result in spontaneous firing of ganglion cells. This ganglion cell activity could interfere with external stimuli provided by retinal prosthetic devices and potentially degrade their performance. In this work, the authors computationally investigate stimulus waveform designs, which can improve the performance of retinal prostheses by suppressing undesired spontaneous firing of ganglion cells and generating precise temporal spiking patterns. They utilise a multi-scale computational model for electrical stimulation of degenerated retina based on the admittance method and NEURON simulation environments. They present a class of asymmetric biphasic pulses that can generate precise ganglion cell firing patterns with up to 55% lower current requirements compared to traditional symmetric biphasic pulses. This lower current results in activation of only proximal ganglion cells, provides more focused stimulation and lowers the risk of tissue damage.
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Affiliation(s)
- Pragya Kosta
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA
| | - Kyle Loizos
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Gianluca Lazzi
- Department of Electrical 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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16
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Retinal Drug Delivery: Rethinking Outcomes for the Efficient Replication of Retinal Behavior. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10124258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The retina is a highly organized structure that is considered to be "an approachable part of the brain." It is attracting the interest of development scientists, as it provides a model neurovascular system. Over the last few years, we have been witnessing significant development in the knowledge of the mechanisms that induce the shape of the retinal vascular system, as well as knowledge of disease processes that lead to retina degeneration. Knowledge and understanding of how our vision works are crucial to creating a hardware-adaptive computational model that can replicate retinal behavior. The neuronal system is nonlinear and very intricate. It is thus instrumental to have a clear view of the neurophysiological and neuroanatomic processes and to take into account the underlying principles that govern the process of hardware transformation to produce an appropriate model that can be mapped to a physical device. The mechanistic and integrated computational models have enormous potential toward helping to understand disease mechanisms and to explain the associations identified in large model-free data sets. The approach used is modulated and based on different models of drug administration, including the geometry of the eye. This work aimed to review the recently used mathematical models to map a directed retinal network.
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Tong W, Meffin H, Garrett DJ, Ibbotson MR. Stimulation Strategies for Improving the Resolution of Retinal Prostheses. Front Neurosci 2020; 14:262. [PMID: 32292328 PMCID: PMC7135883 DOI: 10.3389/fnins.2020.00262] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/09/2020] [Indexed: 12/17/2022] Open
Abstract
Electrical stimulation using implantable devices with arrays of stimulating electrodes is an emerging therapy for neurological diseases. The performance of these devices depends greatly on their ability to activate populations of neurons with high spatiotemporal resolution. To study electrical stimulation of populations of neurons, retina serves as a useful model because the neural network is arranged in a planar array that is easy to access. Moreover, retinal prostheses are under development to restore vision by replacing the function of damaged light sensitive photoreceptors, which makes retinal research directly relevant for curing blindness. Here we provide a progress review on stimulation strategies developed in recent years to improve the resolution of electrical stimulation in retinal prostheses. We focus on studies performed with explanted retinas, in which electrophysiological techniques are the most advanced. We summarize achievements in improving the spatial and temporal resolution of electrical stimulation of the retina and methods to selectively stimulate neurons with different visual functions. Future directions for retinal prostheses development are also discussed, which could provide insights for other types of neuromodulatory devices in which high-resolution electrical stimulation is required.
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Affiliation(s)
- Wei Tong
- National Vision Research Institute, Australian College of Optometry, Carlton, VIC, Australia
- Department of Optometry and Vision Sciences, Melbourne School of Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC, Australia
| | - Hamish Meffin
- National Vision Research Institute, Australian College of Optometry, Carlton, VIC, Australia
- Department of Optometry and Vision Sciences, Melbourne School of Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - David J. Garrett
- School of Physics, The University of Melbourne, Melbourne, VIC, Australia
| | - Michael R. Ibbotson
- National Vision Research Institute, Australian College of Optometry, Carlton, VIC, Australia
- Department of Optometry and Vision Sciences, Melbourne School of Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
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18
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Piech DK, Johnson BC, Shen K, Ghanbari MM, Li KY, Neely RM, Kay JE, Carmena JM, Maharbiz MM, Muller R. A wireless millimetre-scale implantable neural stimulator with ultrasonically powered bidirectional communication. Nat Biomed Eng 2020; 4:207-222. [PMID: 32076132 DOI: 10.1038/s41551-020-0518-9] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/14/2020] [Indexed: 01/06/2023]
Abstract
Clinically approved neural stimulators are limited by battery requirements, as well as by their large size compared with the stimulation targets. Here, we describe a wireless, leadless and battery-free implantable neural stimulator that is 1.7 mm3 and that incorporates a piezoceramic transducer, an energy-storage capacitor and an integrated circuit. An ultrasonic link and a hand-held external transceiver provide the stimulator with power and bidirectional communication. The stimulation protocols were wirelessly encoded on the fly, reducing power consumption and on-chip memory, and enabling protocol complexity with a high temporal resolution and low-latency feedback. Uplink data indicating whether stimulation occurs are encoded by the stimulator through backscatter modulation and are demodulated at the external transceiver. When embedded in ex vivo porcine tissue, the integrated circuit efficiently harvested ultrasonic power, decoded downlink data for the stimulation parameters and generated current-controlled stimulation pulses. When cuff-mounted and acutely implanted onto the sciatic nerve of anaesthetized rats, the device conferred repeatable stimulation across a range of physiological responses. The miniaturized neural stimulator may facilitate closed-loop neurostimulation for therapeutic interventions.
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Affiliation(s)
- David K Piech
- The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, USA.,The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA, USA
| | - Benjamin C Johnson
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA.,Department of Electrical Engineering and Computer Engineering, Boise State University, Boise, ID, USA
| | - Konlin Shen
- The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, USA.,The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA, USA
| | - M Meraj Ghanbari
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Ka Yiu Li
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Ryan M Neely
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Joshua E Kay
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Jose M Carmena
- The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, USA. .,The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA, USA. .,Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA. .,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA.
| | - Michel M Maharbiz
- The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, USA. .,The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA, USA. .,Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA. .,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
| | - Rikky Muller
- The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, USA. .,The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA, USA. .,Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
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Xie H, Shek CH, Wang Y, Chan LLH. Effect of interphase gap duration and stimulus rate on threshold of visual cortical neurons in the rat. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:1817-1820. [PMID: 31946250 DOI: 10.1109/embc.2019.8856829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Stimulation threshold is a key parameter to enable an efficient design for retinal implants. Stimulation parameters such as stimulus pulse duration, pulse amplitude, pulse repetition, pulse shape and polarity have been shown to be the key factors that can influence the efficacy of retinal prosthetics. The effectiveness of these devices should best be evaluated both in the retina and in the visual cortex. Prior electrophysiological studies in the retina have shown that introducing an interphase gap make stimulation more efficient. Previous in vitro studies have also demonstrated the response properties of retinal ganglion cells are frequency dependent. However, the effect of these two stimulus parameters are not well explored at the cortical level where higher visual processing signals are processed. In this study, we examined the response properties of visual cortical neurons under stimulation of retinal ganglion cells in rat using a single-channel electrode of diameter 75 μm. We compared the response strength curves as a function of stimulus current amplitudes under different stimulus pulse duration, interphase gap and stimulus rate. Localized response to single channel epiretinal stimulation was robustly observed in V1 neurons. We found that V1 neurons were more sensitive to longer pulse and stimulus with an interphase gap, similar to previously reported results in the retina. We were also able to examine the effect of stimulus frequency on threshold in the visual cortex. Our results indicate that electrical activation of V1 neurons are more efficient at low frequency.
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20
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Soto-Breceda A, Kameneva T, Meffin H, Maturana M, Ibbotson MR. Irregularly timed electrical pulses reduce adaptation of retinal ganglion cells. J Neural Eng 2018; 15:056017. [PMID: 30021932 DOI: 10.1088/1741-2552/aad46e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Retinal prostheses aim to provide visual percepts to blind people affected by diseases caused by photoreceptor degeneration. One of the main challenges presented by current devices is neural adaptation in the retina, which is believed to be the cause of fading-an effect where artificially produced percepts disappear over a short period of time, despite continuous stimulation of the retina. We aim to understand the neural adaptation generated in retinal ganglion cells (RGCs) during electrical stimulation. APPROACH Current visual prostheses use electrical pulses with fixed frequencies and amplitudes modulated over hundreds of milliseconds to stimulate the retina. However, in nature, neuronal spiking occurs with stochastic timing, hence the information received naturally from other neurons by RGCs is irregularly timed. We used a single epiretinal electrode to stimulate and compare rat RGC responses to stimulus trains of biphasic pulses delivered at regular and random inter-pulse intervals (IPI), the latter taken from an exponential distribution. MAIN RESULTS Our observations suggest that stimulation with random IPIs result in lower adaptation rates than stimulation with constant IPIs at frequencies of 50 Hz and 200 Hz. We also found a high proportion of lower amplitude action potentials, or spikelets. The spikelets were more prominent at high stimulation frequencies (50 Hz and 200 Hz) and were less susceptible to adaptation, but it was not clear if they propagated along the axon. SIGNIFICANCE Using random IPI stimulation in retinal prostheses reduces the decay of RGCs and this could potentially reduce fading of electrically induced visual perception.
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Affiliation(s)
- A Soto-Breceda
- National Vision Research Institute, Australian College of Optometry, Melbourne, Australia. Department of Biomedical Engineering, The University of Melbourne, Melbourne, Australia. CSIRO, Data 61, Melbourne, Australia
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Bareket L, Barriga-Rivera A, Zapf MP, Lovell NH, Suaning GJ. Progress in artificial vision through suprachoroidal retinal implants. J Neural Eng 2018; 14:045002. [PMID: 28541930 DOI: 10.1088/1741-2552/aa6cbb] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Retinal implants have proven their ability to restore visual sensation to people with degenerative retinopathy, characterized by photoreceptor cell death and the retina's inability to sense light. Retinal bionics operate by electrically stimulating the surviving neurons in the retina, thus triggering the transfer of visual sensory information to the brain. Suprachoroidal implants were first investigated in Australia in the 1950s. In this approach, the neuromodulation hardware is positioned between the sclera and the choroid, thus providing significant surgical and safety benefits for patients, with the potential to maintain residual vision combined with the artificial input from the device. Here we review the latest advances and state of the art devices for suprachoroidal prostheses, highlight future technologies and discuss challenges and perspectives towards improved rehabilitation of vision.
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Affiliation(s)
- Lilach Bareket
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
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22
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Loizos K, Marc R, Humayun M, Anderson JR, Jones BW, Lazzi G. Increasing Electrical Stimulation Efficacy in Degenerated Retina: Stimulus Waveform Design in a Multiscale Computational Model. IEEE Trans Neural Syst Rehabil Eng 2018; 26:1111-1120. [PMID: 29877835 PMCID: PMC6005361 DOI: 10.1109/tnsre.2018.2832055] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A computational model of electrical stimulation of the retina is proposed for investigating current waveforms used in prosthetic devices for restoring partial vision lost to retinal degenerative diseases. The model framework combines a connectome-based neural network model characterized by accurate morphological and synaptic properties with an admittance method model of bulk tissue and prosthetic electronics. In this model, the retina was computationally "degenerated," considering cellular death and anatomical changes that occur early in disease, as well as altered neural behavior that develops throughout the neurodegeneration and is likely interfering with current attempts at restoring vision. A resulting analysis of stimulation range and threshold of ON ganglion cells within the retina that are either healthy or in beginning stages of degeneration is presented for currently used stimulation waveforms, and an asymmetric biphasic current stimulation for subduing spontaneous firing to allow increased control over ganglion cell firing patterns in degenerated retina is proposed. Results show that stimulation thresholds of retinal ganglion cells do not notably vary after beginning stages of retina degeneration. In addition, simulation of proposed asymmetric waveforms showed the ability to enhance the control of ganglion cell firing via electrical stimulation.
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23
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Walston ST, Chow RH, Weiland JD. Direct measurement of bipolar cell responses to electrical stimulation in wholemount mouse retina. J Neural Eng 2018. [PMID: 29513646 DOI: 10.1088/1741-2552/aab4ed] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE This in vitro investigation examines the response of retinal bipolar cells to extracellular electrical stimulation. APPROACH In vitro investigations characterizing the response of retinal neurons to electrical stimulation have primarily focused on retinal ganglion cells because they are the output neurons of the retina and their superficial position in the retina makes them readily accessible to in vitro recording techniques. Thus, the majority of information regarding the response of inner retinal neurons has been inferred from ganglion cell activity. Here we use patch clamp electrophysiology to directly record electrically-evoked activity in bipolar cells within the inner retina of normal Tg(Gng13-EGFP)GI206Gsat and degenerate rd10 Tg(Gng13-EGFP)GI206Gsat mice using a wholemount preparation. MAIN RESULTS Bipolar cells respond to electrical stimulation with time-locked depolarizing voltage transients. The latency of the response declines with increases in stimulation amplitude. A desensitizing response is observed during repeated stimulation with 25 ms biphasic current pulses delivered at pulse rates greater than 6 pps. A burst of long-latency (200-1000 ms) inhibitory postsynaptic potentials are evoked by the stimulus and the burst exhibits evidence of a lower and upper stimulation threshold. SIGNIFICANCE These results provide insights into the various types of bipolar cell activity elicited by electrical stimulation and may be useful for future retinal prosthesis stimulation protocols. This investigation uses patch clamp electrophysiology to provide direct analysis of ON-type bipolar cell responses to electrical stimulation in a wholemount retina preparation. It explores the effects of variable stimulus amplitudes, pulse widths, and frequencies in both normal and degenerate retina. The analysis adds to a body of work largely based upon indirect measurements of bipolar cell activity, and the methodology demonstrates an alternative retina preparation technique in which to acquire single-cell activity.
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Affiliation(s)
- Steven T Walston
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90007, United States of America
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Carraro U. Exciting perspectives for Translational Myology in the Abstracts of the 2018Spring PaduaMuscleDays: Giovanni Salviati Memorial - Chapter IV - Abstracts of March 17, 2018. Eur J Transl Myol 2018; 28:7366. [PMID: 30057728 PMCID: PMC6047882 DOI: 10.4081/ejtm.2018.7366] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 02/20/2018] [Indexed: 02/08/2023] Open
Abstract
Myologists working in Padua (Italy) were able to continue a half-century tradition of studies of skeletal muscles, that started with a research on fever, specifically if and how skeletal muscle contribute to it by burning bacterial toxin. Beside main publications in high-impact-factor journals by Padua myologists, I hope to convince readers (and myself) of the relevance of the editing Basic and Applied Myology (BAM), retitled from 2010 European Journal of Translational Myology (EJTM), of the institution of the Interdepartmental Research Center of Myology of the University of Padova (CIR-Myo), and of a long series of International Conferences organized in Euganei Hills and Padova, that is, the PaduaMuscleDays. The 2018Spring PaduaMuscleDays (2018SpPMD), were held in Euganei Hills and Padua (Italy), in March 14-17, and were dedicated to Giovanni Salviati. The main event of the “Giovanni Salviati Memorial”, was held in the Aula Guariento, Accademia Galileiana di Scienze, Lettere ed Arti of Padua to honor a beloved friend and excellent scientist 20 years after his premature passing. Using the words of Prof. Nicola Rizzuto, we all share his believe that Giovanni “will be remembered not only for his talent and originality as a biochemist, but also for his unassuming and humanistic personality, a rare quality in highly successful people like Giovanni. The best way to remember such a person is to gather pupils and colleagues, who shared with him the same scientific interests and ask them to discuss recent advances in their own fields, just as Giovanni have liked to do”. Since Giovanni’s friends sent many abstracts still influenced by their previous collaboration with him, all the Sessions of the 2018SpPMD reflect both to the research aims of Giovanni Salviati and the traditional topics of the PaduaMuscleDays, that is, basics and applications of physical, molecular and cellular strategies to maintain or recover functions of skeletal muscles. The translational researches summarized in the 2018SpPMD Abstracts are at the appropriate high level to attract endorsement of Ethical Committees, the interest of International Granting Agencies and approval for publication in top quality international journals. The abstracts of the presentations of the March 16, 2018 Padua Muscle Day and those of the remaining Posters are listed in this chapter IV. The Author Index of the 2018Spring PaduaMuscleDays follows at page 78.
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Affiliation(s)
- Ugo Carraro
- Laboratory of Translational Myology, Department of Biomedical Sciences, University of Padova.,A&C M-C Foundation for Translational Myology, Padova.,IRCCS Fondazione Ospedale San Camillo, Venezia-Lido, Italy
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Daneshzand M, Faezipour M, Barkana BD. Computational Stimulation of the Basal Ganglia Neurons with Cost Effective Delayed Gaussian Waveforms. Front Comput Neurosci 2017; 11:73. [PMID: 28848417 PMCID: PMC5550730 DOI: 10.3389/fncom.2017.00073] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/25/2017] [Indexed: 11/16/2022] Open
Abstract
Deep brain stimulation (DBS) has compelling results in the desynchronization of the basal ganglia neuronal activities and thus, is used in treating the motor symptoms of Parkinson's disease (PD). Accurate definition of DBS waveform parameters could avert tissue or electrode damage, increase the neuronal activity and reduce energy cost which will prolong the battery life, hence avoiding device replacement surgeries. This study considers the use of a charge balanced Gaussian waveform pattern as a method to disrupt the firing patterns of neuronal cell activity. A computational model was created to simulate ganglia cells and their interactions with thalamic neurons. From the model, we investigated the effects of modified DBS pulse shapes and proposed a delay period between the cathodic and anodic parts of the charge balanced Gaussian waveform to desynchronize the firing patterns of the GPe and GPi cells. The results of the proposed Gaussian waveform with delay outperformed that of rectangular DBS waveforms used in in-vivo experiments. The Gaussian Delay Gaussian (GDG) waveforms achieved lower number of misses in eliciting action potential while having a lower amplitude and shorter length of delay compared to numerous different pulse shapes. The amount of energy consumed in the basal ganglia network due to GDG waveforms was dropped by 22% in comparison with charge balanced Gaussian waveforms without any delay between the cathodic and anodic parts and was also 60% lower than a rectangular charged balanced pulse with a delay between the cathodic and anodic parts of the waveform. Furthermore, by defining a Synchronization Level metric, we observed that the GDG waveform was able to reduce the synchronization of GPi neurons more effectively than any other waveform. The promising results of GDG waveforms in terms of eliciting action potential, desynchronization of the basal ganglia neurons and reduction of energy consumption can potentially enhance the performance of DBS devices.
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Affiliation(s)
- Mohammad Daneshzand
- D-BEST Lab, Departments of Computer Science and Engineering and Biomedical Engineering, University of BridgeportBridgeport, CT, United States
| | - Miad Faezipour
- D-BEST Lab, Departments of Computer Science and Engineering and Biomedical Engineering, University of BridgeportBridgeport, CT, United States
| | - Buket D Barkana
- Department of Electrical Engineering, University of BridgeportBridgeport, CT, United States
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Pette D. What Can be Learned from the Time Course of Changes in Low-Frequency Stimulated Muscle? Eur J Transl Myol 2017; 27:6723. [PMID: 28713537 PMCID: PMC5505094 DOI: 10.4081/ejtm.2017.6723] [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] [Indexed: 11/24/2022] Open
Abstract
Not available.
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Affiliation(s)
- Dirk Pette
- Department of Biology, University of Konstanz, Germany
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27
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Wu J, Jin M, Qiao Q. Modeling electrical stimulation of retinal ganglion cell with optimizing additive noises for reducing threshold and energy consumption. Biomed Eng Online 2017; 16:38. [PMID: 28347343 PMCID: PMC5368944 DOI: 10.1186/s12938-017-0333-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 03/20/2017] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Epiretinal prosthesis is one device for the treatment of blindness, which target retinal ganglion cells (RGCs) by electrodes on retinal surface. The stimulating current of epiretinal prosthesis is an important factor that influences the safety threshold and visual perception. Stochastic resonance (SR) can be used to enhance the detection and transmission of subthreshold stimuli in neurons. Here, it was assumed that SR was a potential way to improve the performance of epiretinal prosthesis. The effect of noises on the response of RGCs to electrical stimulation and the energy of stimulating current was studied based on a RGC model. METHODS The RGC was modeled as a multi-compartment model consisting of dendrites and its branches, soma and axon. To evoke SR, a subthreshold signal, a series of bipolar rectangular pulse sequences, plus stochastic biphasic pulse sequences as noises, were used as a stimulus to the model. The SR-type behavior in the model was characterized by a "power norm" measure. To decrease energy consumption of the stimulation waveform, the stochastic biphasic pulse sequences were only added to the cathode and anode phase of the subthreshold pulse and the noise parameters were optimized by using a genetic algorithm (GA). RESULTS When certain intensity of noise is added to the subthreshold signal, RGC model can fire. With the noise's RMS amplitudes increased, more spikes were elicited and the curve of power norm presents the inverted U-like graph. The larger pulse width of stochastic biphasic pulse sequences resulted in higher power norm. The energy consumption and charges of the single bipolar rectangular pulse without noise in threshold level are 468.18 pJ, 15.30 nC, and after adding optimized parameters's noise to the subthreshold signal, they became 314.8174 pJ, 11.9281 nC and were reduced by 32.8 and 22.0%, respectively. CONCLUSIONS The SR exists in the RGC model and can enhance the representation of RGC model to the subthreshold signal. Adding the stochastic biphasic pulse sequences to the cathode and anode phase of the subthreshold signal helps to reduce stimulation threshold, energy consumption and charge of RGC stimulation. These may be helpful for improving the performance of epiretinal prosthesis.
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Affiliation(s)
- Jing Wu
- School of Biomedical Engineering & Technology, Tianjin Medical University, Tianjin, 300070 China
| | - Menghua Jin
- School of Biomedical Engineering & Technology, Tianjin Medical University, Tianjin, 300070 China
| | - Qingli Qiao
- School of Biomedical Engineering & Technology, Tianjin Medical University, Tianjin, 300070 China
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28
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Weitz AC, Nanduri D, Behrend MR, Gonzalez-Calle A, Greenberg RJ, Humayun MS, Chow RH, Weiland JD. Improving the spatial resolution of epiretinal implants by increasing stimulus pulse duration. Sci Transl Med 2016; 7:318ra203. [PMID: 26676610 DOI: 10.1126/scitranslmed.aac4877] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Retinal prosthetic implants are the only approved treatment for retinitis pigmentosa, a disease of the eye that causes blindness through gradual degeneration of photoreceptors. An array of microelectrodes triggered by input from a camera stimulates surviving retinal neurons, with each electrode acting as a pixel. Unintended stimulation of retinal ganglion cell axons causes patients to see large oblong shapes of light, rather than focal spots, making it difficult to perceive forms. To address this problem, we performed calcium imaging in isolated retinas and mapped the patterns of cells activated by different electrical stimulation protocols. We found that pulse durations two orders of magnitude longer than those typically used in existing implants stimulated inner retinal neurons while avoiding activation of ganglion cell axons, thus confining retinal responses to the site of the electrode. Multielectrode stimulation with 25-ms pulses can pattern letters on the retina corresponding to a Snellen acuity of 20/312. We validated our findings in a patient with an implanted epiretinal prosthesis by demonstrating that 25-ms pulses evoke focal spots of light.
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Affiliation(s)
- Andrew C Weitz
- Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Devyani Nanduri
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Matthew R Behrend
- Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Alejandra Gonzalez-Calle
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | | | - Mark S Humayun
- Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Robert H Chow
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA. Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
| | - James D Weiland
- Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA.
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29
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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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30
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Becher M, Springer S, Braun-Benyamin O, Laufer Y. The Effect of an Interphase Interval on Electrically Induced Dorsiflexion Force and Fatigue in Subjects With an Upper Motor Neuron Lesion. Artif Organs 2016; 40:778-85. [DOI: 10.1111/aor.12698] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/19/2015] [Accepted: 12/21/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Meni Becher
- Department of Physical Therapy, The Faculty of Social Welfare and Health Sciences; University of Haifa; Haifa
- Clinical Department; Bioness Neuromodulation; Ra'anana
| | - Shmuel Springer
- Department of Physical Therapy; The Faculty of Health Sciences, Ariel University; Ariel
| | - Orit Braun-Benyamin
- Department of Physical Therapy, The Faculty of Social Welfare and Health Sciences; University of Haifa; Haifa
- Department of Mechanical Engineering; Ort Braude; Carmiel Israel
| | - Yocheved Laufer
- Department of Physical Therapy, The Faculty of Social Welfare and Health Sciences; University of Haifa; Haifa
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31
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Editors T. Muscle Decline in Aging and Neuromuscular Disorders - Mechanisms and Countermeasures: Terme Euganee, Padova (Italy), April 13-16, 2016. Eur J Transl Myol 2016; 26:5904. [PMID: 27054021 PMCID: PMC4821223 DOI: 10.4081/ejtm.2016.5904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Not available.
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32
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Horne CDF, Sumner CJ, Seeber BU. A Phenomenological Model of the Electrically Stimulated Auditory Nerve Fiber: Temporal and Biphasic Response Properties. Front Comput Neurosci 2016; 10:8. [PMID: 26903850 PMCID: PMC4744847 DOI: 10.3389/fncom.2016.00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/18/2016] [Indexed: 11/13/2022] Open
Abstract
We present a phenomenological model of electrically stimulated auditory nerve fibers (ANFs). The model reproduces the probabilistic and temporal properties of the ANF response to both monophasic and biphasic stimuli, in isolation. The main contribution of the model lies in its ability to reproduce statistics of the ANF response (mean latency, jitter, and firing probability) under both monophasic and cathodic-anodic biphasic stimulation, without changing the model's parameters. The response statistics of the model depend on stimulus level and duration of the stimulating pulse, reproducing trends observed in the ANF. In the case of biphasic stimulation, the model reproduces the effects of pseudomonophasic pulse shapes and also the dependence on the interphase gap (IPG) of the stimulus pulse, an effect that is quantitatively reproduced. The model is fitted to ANF data using a procedure that uniquely determines each model parameter. It is thus possible to rapidly parameterize a large population of neurons to reproduce a given set of response statistic distributions. Our work extends the stochastic leaky integrate and fire (SLIF) neuron, a well-studied phenomenological model of the electrically stimulated neuron. We extend the SLIF neuron so as to produce a realistic latency distribution by delaying the moment of spiking. During this delay, spiking may be abolished by anodic current. By this means, the probability of the model neuron responding to a stimulus is reduced when a trailing phase of opposite polarity is introduced. By introducing a minimum wait period that must elapse before a spike may be emitted, the model is able to reproduce the differences in the threshold level observed in the ANF for monophasic and biphasic stimuli. Thus, the ANF response to a large variety of pulse shapes are reproduced correctly by this model.
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Affiliation(s)
- Colin D F Horne
- Medical Research Council Institute of Hearing Research, University Park Nottingham, UK
| | - Christian J Sumner
- Medical Research Council Institute of Hearing Research, University Park Nottingham, UK
| | - Bernhard U Seeber
- Audio Information Processing, Department of Electrical and Computer Engineering, Technische Universität München Munich, Germany
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33
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Abstract
Not available.
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34
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Tanamoto R, Shindo Y, Miki N, Matsumoto Y, Hotta K, Oka K. Electrical stimulation of cultured neurons using a simply patterned indium-tin-oxide (ITO) glass electrode. J Neurosci Methods 2015; 253:272-8. [PMID: 26185873 DOI: 10.1016/j.jneumeth.2015.07.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 07/03/2015] [Accepted: 07/04/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND Indium-tin-oxide (ITO) glass electrodes possess the properties of optical transparency and high electrical conductivity, which enables the electrical stimulation of cultured cells to be performed whilst also measuring the responses with fluorescent imaging techniques. However, the quantitative relationship between the intensity of the stimulating current and the cell response is unclear when using conventional methods that employ a separated configuration of counter and stimulation electrodes. NEW METHOD A quantitative electrical current stimulation device without the use of a counter electrode was fabricated. RESULTS Nerve growth factor (NGF)-induced differentiated PC12 cells were cultured on an ITO single glass electrode, and the Ca(2+) response to electrical stimuli was measured using fluorescent Ca(2+) imaging. ITO electrode devices with a width less than 0.1mm were found to evoke a Ca(2+) response in the PC12 cells. Subsequent variation in the length of the device in the range of 2-10mm was found to have little influence on the efficiency of the electric stimulus. We found that the stimulation of the cells was dependent on the electrical current, when greater than 60 μA, rather than on the Joule heat, regardless of the width and length of the conductive area. COMPARISON WITH EXISTING METHOD(S) Because of the cells directly in contact with the electrode, our device enables to stimulate the cells specifically, comparing with previous devices with the counter electrode. CONCLUSIONS The ITO device without the use of a counter electrode is a useful tool for evaluating the quantitative neural excitability of cultured neurons.
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Affiliation(s)
- Ryo Tanamoto
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
| | - Yutaka Shindo
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
| | - Norihisa Miki
- Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
| | - Yoshinori Matsumoto
- Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
| | - Kohji Hotta
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
| | - Kotaro Oka
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.
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Maciejasz P, Badia J, Boretius T, Andreu D, Stieglitz T, Jensen W, Navarro X, Guiraud D. Delaying discharge after the stimulus significantly decreases muscle activation thresholds with small impact on the selectivity: an in vivo study using TIME. Med Biol Eng Comput 2015; 53:371-9. [PMID: 25652078 DOI: 10.1007/s11517-015-1244-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 01/22/2015] [Indexed: 10/24/2022]
Abstract
The number of devices for electrical stimulation of nerve fibres implanted worldwide for medical applications is constantly increasing. Stimulation charge is one of the most important parameters of stimulation. High stimulation charge may cause tissue and electrode damage and also compromise the battery life of the electrical stimulators. Therefore, the objective of minimizing stimulation charge is an important issue. Delaying the second phase of biphasic stimulation waveform may decrease the charge required for fibre activation, but its impact on stimulation selectivity is not known. This information is particularly relevant when transverse intrafascicular multichannel electrode (TIME) is used, since it has been designed to provide for high selectivity. In this in vivo study, the rat sciatic nerve was electrically stimulated using monopolar and bipolar configurations with TIME. The results demonstrated that the inclusion of a 100-μs delay between the cathodic and the anodic phase of the stimulus allows to reduce charge requirements by around 30 %, while only slightly affecting stimulation selectivity. This study shows that adding a delay to the typical stimulation waveform significantly ([Formula: see text]) reduces the charge required for nerve fibres activation. Therefore, waveforms with the delayed discharge phase are more suitable for electrical stimulation of nerve fibres.
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Affiliation(s)
- Paweł Maciejasz
- DEMAR Team, LIRMM, INRIA, University of Montpellier 2, Montpellier, France,
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Marc R, Pfeiffer R, Jones B. Retinal prosthetics, optogenetics, and chemical photoswitches. ACS Chem Neurosci 2014; 5:895-901. [PMID: 25089879 PMCID: PMC4210130 DOI: 10.1021/cn5001233] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
![]()
Three
technologies have emerged as therapies to restore light sensing to
profoundly blind patients suffering from late-stage retinal degenerations:
(1) retinal prosthetics, (2) optogenetics, and (3) chemical photoswitches.
Prosthetics are the most mature and the only approach in clinical
practice. Prosthetic implants require complex surgical intervention
and provide only limited visual resolution but can potentially restore
navigational ability to many blind patients. Optogenetics uses viral
delivery of type 1 opsin genes from prokaryotes or eukaryote algae
to restore light responses in survivor neurons. Targeting and expression
remain major problems, but are potentially soluble. Importantly, optogenetics
could provide the ultimate in high-resolution vision due to the long
persistence of gene expression achieved in animal models. Nevertheless,
optogenetics remains challenging to implement in human eyes with large
volumes, complex disease progression, and physical barriers to viral
penetration. Now, a new generation of photochromic ligands or chemical
photoswitches (azobenzene-quaternary ammonium derivatives) can be
injected into a degenerated mouse eye and, in minutes to hours, activate
light responses in neurons. These photoswitches offer the potential
for rapidly and reversibly screening the vision restoration expected
in an individual patient. Chemical photoswitch variants that persist
in the cell membrane could make them a simple therapy of choice, with
resolution and sensitivity equivalent to optogenetics approaches.
A major complexity in treating retinal degenerations is retinal remodeling:
pathologic network rewiring, molecular reprogramming, and cell death
that compromise signaling in the surviving retina. Remodeling forces
a choice between upstream and downstream targeting, each engaging
different benefits and defects. Prosthetics and optogenetics can be
implemented in either mode, but the use of chemical photoswitches
is currently limited to downstream implementations. Even so, given
the high density of human foveal ganglion cells, the ultimate chemical
photoswitch treatment could deliver cost-effective, high-resolution
vision for the blind.
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Affiliation(s)
- Robert Marc
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah 84132, United States
| | - Rebecca Pfeiffer
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah 84132, United States
| | - Bryan Jones
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah 84132, United States
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