1
|
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.
Collapse
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
| |
Collapse
|
2
|
Govindarajan LN, Calvert JS, Parker SR, Jung M, Darie R, Miranda P, Shaaya E, Borton DA, Serre T. Fast inference of spinal neuromodulation for motor control using amortized neural networks. J Neural Eng 2022; 19:10.1088/1741-2552/ac9646. [PMID: 36174534 PMCID: PMC9668352 DOI: 10.1088/1741-2552/ac9646] [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: 05/31/2022] [Accepted: 09/29/2022] [Indexed: 11/12/2022]
Abstract
Objective.Epidural electrical stimulation (EES) has emerged as an approach to restore motor function following spinal cord injury (SCI). However, identifying optimal EES parameters presents a significant challenge due to the complex and stochastic nature of muscle control and the combinatorial explosion of possible parameter configurations. Here, we describe a machine-learning approach that leverages modern deep neural networks to learn bidirectional mappings between the space of permissible EES parameters and target motor outputs.Approach.We collected data from four sheep implanted with two 24-contact EES electrode arrays on the lumbosacral spinal cord. Muscle activity was recorded from four bilateral hindlimb electromyography (EMG) sensors. We introduce a general learning framework to identify EES parameters capable of generating desired patterns of EMG activity. Specifically, we first amortize spinal sensorimotor computations in a forward neural network model that learns to predict motor outputs based on EES parameters. Then, we employ a second neural network as an inverse model, which reuses the amortized knowledge learned by the forward model to guide the selection of EES parameters.Main results.We found that neural networks can functionally approximate spinal sensorimotor computations by accurately predicting EMG outputs based on EES parameters. The generalization capability of the forward model critically benefited our inverse model. We successfully identified novel EES parameters, in under 20 min, capable of producing desired target EMG recruitment duringin vivotesting. Furthermore, we discovered potential functional redundancies within the spinal sensorimotor networks by identifying unique EES parameters that result in similar motor outcomes. Together, these results suggest that our framework is well-suited to probe spinal circuitry and control muscle recruitment in a completely data-driven manner.Significance.We successfully identify novel EES parameters within minutes, capable of producing desired EMG recruitment. Our approach is data-driven, subject-agnostic, automated, and orders of magnitude faster than manual approaches.
Collapse
Affiliation(s)
- Lakshmi Narasimhan Govindarajan
- Cognitive, Linguistic & Psychological Sciences, Brown University, Providence RI USA
- Carney Institute for Brain Science, Brown University, Providence RI USA
| | | | | | - Minju Jung
- Cognitive, Linguistic & Psychological Sciences, Brown University, Providence RI USA
- Carney Institute for Brain Science, Brown University, Providence RI USA
| | - Radu Darie
- School of Engineering, Brown University, Providence RI USA
| | | | - Elias Shaaya
- Department of Neurosurgery, Brown University and Rhode Island Hospital, Providence RI USA
| | - David A. Borton
- Carney Institute for Brain Science, Brown University, Providence RI USA
- School of Engineering, Brown University, Providence RI USA
- Center for Neurorestoration and Neurotechnology, Department of Veterans Affairs, Providence RI USA
| | - Thomas Serre
- Cognitive, Linguistic & Psychological Sciences, Brown University, Providence RI USA
- Carney Institute for Brain Science, Brown University, Providence RI USA
| |
Collapse
|
3
|
Liu X, Xu Z, Fu X, Liu Y, Jia H, Yang Z, Zhang J, Wei S, Duan X. Stable, long-term single-neuronal recording from the rat spinal cord with flexible carbon nanotube fiber electrodes. J Neural Eng 2022; 19. [DOI: 10.1088/1741-2552/ac9258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 09/15/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Objective. Flexible implantable electrodes enable months-long stable recording of single-unit signals from rat brains. Despite extensive efforts in the development of flexible probes for brain recording, thus far there are no conclusions on their application in long-term single neuronal recording from the spinal cord which is more mechanically active. To this end, we realized the chronic recording of single-unit signals from the spinal cord of freely-moving rats using flexible carbon nanotube fiber (CNTF) electrodes. Approach. We developed flexible CNTF electrodes for intraspinal recording. Continuous in vivo impedance monitoring and histology studies were conducted to explore the critical factors determining the longevity of the recording, as well as to illustrate the evolution of the electrode-tissue interface. Gait analysis were performed to evaluate the biosafety of the chronic intraspinal implantation of the CNTF electrodes. Main results. By increasing the insulation thickness of the CNTF electrodes, single-unit signals were continuously recorded from the spinal cord of freely-moving rats without electrode repositioning for 3-4 months. Single neuronal and local field potential activities in response to somatic mechanical stimulation were successfully recorded from the spinal dorsal horns. Histological data demonstrated the ability of the CNTF microelectrodes to form an improved intraspinal interfaces with greatly reduced gliosis compared to their stiff metal counterparts. Continuous impedance monitoring suggested that the longevity of the intraspinal recording with CNTF electrodes was determined by the insulation durability. Gait analysis showed that the chronic presence of the CNTF electrodes caused no noticeable locomotor deficits in rats. Significance. It was found that the chronic recording from the spinal cord faces more stringent requirements on the electrode structural durability than recording from the brain. The stable, long-term intraspinal recording provides unique capabilities for studying the physiological functions of the spinal cord relating to motor, sensation, and autonomic control in both health and disease.
Collapse
|
4
|
Mirkiani S, Roszko DA, O'Sullivan C, Faridi P, Hu DS, Fang D, Everaert DG, Toossi A, Konrad PE, Robinson K, Mushahwar VK. Overground gait kinematics and muscle activation patterns in the Yucatan mini pig. J Neural Eng 2022; 19. [PMID: 35172283 DOI: 10.1088/1741-2552/ac55ac] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/16/2022] [Indexed: 11/12/2022]
Abstract
Objective The objectives of this study were to assess gait biomechanics and the effect of overground walking speed on gait parameters, kinematics, and electromyographic (EMG) activity in the hindlimb muscles of Yucatan Minipigs (YMPs). Approach Nine neurologically-intact, adult YMPs were trained to walk overground in a straight line. Whole-body kinematics and EMG activity of hindlimb muscles were recorded and analyzed at 6 different speed ranges (0.4-0.59, 0.6-0.79, 0.8-0.99, 1.0-1.19, 1.2-1.39, and 1.4-1.6 m/s). A MATLAB program was developed to detect strides and gait events automatically from motion-captured data. The kinematics and EMG activity were analyzed for each stride based on the detected events. Main results Significant decreases in stride duration, stance and swing times and an increase in stride length were observed with increasing speed. A transition in gait pattern occurred at the 1.0m/s walking speed. Significant increases in the range of motion of the knee and ankle joints were observed at higher speeds. Also, the points of minimum and maximum joint angles occurred earlier in the gait cycle as the walking speed increased. The onset of EMG activity in the biceps femoris muscle occurred significantly earlier in the gait cycle with increasing speed. Significance YMPs are becoming frequently used as large animal models for preclinical testing and translation of novel interventions to humans. A comprehensive characterization of overground walking in neurologically-intact YMPs is provided in this study. These normative measures set the basis against which the effects of future interventions on locomotor capacity in YMPs can be compared.
Collapse
Affiliation(s)
- Soroush Mirkiani
- Neuroscience & Mental Health Institute and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, University of Alberta, Edmonton, Alberta, T6G 2R3, CANADA
| | - David A Roszko
- Neuroscience & Mental Health Institute and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, Edmonton, Alberta, T6G 2R3, CANADA
| | - Carly O'Sullivan
- Neuroscience & Mental Health Institute and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz, Building, Edmonton, Alberta, T6G 2R3, CANADA
| | - Pouria Faridi
- Neuroscience & Mental Health Institute and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, Edmonton, Alberta, T6G 2R3, CANADA
| | - David S Hu
- Department of Medicine and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, Edmonton, Alberta, T6G 2R3, CANADA
| | - Daniel Fang
- Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, Edmonton, Alberta, T6G 2R3, CANADA
| | - Dirk G Everaert
- Department of Medicine and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, Edmonton, Alberta, T6G 2R3, CANADA
| | - Amirali Toossi
- Neuroscience & Mental Health Institute and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, Edmonton, Alberta, T6G 2R3, CANADA
| | - Peter E Konrad
- Department of Neurosurgery, West Virginia University, PO Box 9183, Morgantown, West Virginia, 26506, UNITED STATES
| | - Kevin Robinson
- School of Physical Therapy, Belmont University, 341 McWhorter Hall, Nashville, Tennessee, 37212, UNITED STATES
| | - Vivian K Mushahwar
- Department of Medicine and Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, 5005 Katz Building, University of Alberta, Edmonton, Alberta, T6G 2R3, CANADA
| |
Collapse
|
5
|
Mao GW, Zhang JJ, Su H, Zhou ZJ, Zhu LS, Lü XY, Wang ZG. A flexible electrode array for determining regions of motor function activated by epidural spinal cord stimulation in rats with spinal cord injury. Neural Regen Res 2022; 17:601-607. [PMID: 34380900 PMCID: PMC8504402 DOI: 10.4103/1673-5374.320987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epidural stimulation of the spinal cord is a promising technique for the recovery of motor function after spinal cord injury. The key challenges within the reconstruction of motor function for paralyzed limbs are the precise control of sites and parameters of stimulation. To activate lower-limb muscles precisely by epidural spinal cord stimulation, we proposed a high-density, flexible electrode array. We determined the regions of motor function that were activated upon epidural stimulation of the spinal cord in a rat model with complete spinal cord, which was established by a transection method. For evaluating the effect of stimulation, the evoked potentials were recorded from bilateral lower-limb muscles, including the vastus lateralis, semitendinosus, tibialis anterior, and medial gastrocnemius. To determine the appropriate stimulation sites and parameters of the lower muscles, the stimulation characteristics were studied within the regions in which motor function was activated upon spinal cord stimulation. In the vastus lateralis and medial gastrocnemius, these regions were symmetrically located at the lateral site of L1 and the medial site of L2 vertebrae segment, respectively. The tibialis anterior and semitendinosus only responded to stimulation simultaneously with other muscles. The minimum and maximum stimulation threshold currents of the vastus lateralis were higher than those of the medial gastrocnemius. Our results demonstrate the ability to identify specific stimulation sites of lower muscles using a high-density and flexible array. They also provide a reference for selecting the appropriate conditions for implantable stimulation for animal models of spinal cord injury. This study was approved by the Animal Research Committee of Southeast University, China (approval No. 20190720001) on July 20, 2019.
Collapse
Affiliation(s)
- Guang-Wei Mao
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu Province, China
| | - Jian-Jun Zhang
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu Province, China
| | - Hao Su
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu Province, China
| | - Zhi-Jun Zhou
- Institute of RF- & OE-ICs, Southeast University, Nanjing, Jiangsu Province, China
| | - Lin-Sen Zhu
- Institute of RF- & OE-ICs, Southeast University, Nanjing, Jiangsu Province, China
| | - Xiao-Ying Lü
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Zhi-Gong Wang
- Institute of RF- & OE-ICs, Southeast University, Nanjing; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| |
Collapse
|
6
|
Lai BQ, Zeng X, Han WT, Che MT, Ding Y, Li G, Zeng YS. Stem cell-derived neuronal relay strategies and functional electrical stimulation for treatment of spinal cord injury. Biomaterials 2021; 279:121211. [PMID: 34710795 DOI: 10.1016/j.biomaterials.2021.121211] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 10/09/2021] [Accepted: 10/20/2021] [Indexed: 01/06/2023]
Abstract
The inability of adult mammals to recover function lost after severe spinal cord injury (SCI) has been known for millennia and is mainly attributed to a failure of brain-derived nerve fiber regeneration across the lesion. Potential approaches to re-establishing locomotor function rely on neuronal relays to reconnect the segregated neural networks of the spinal cord. Intense research over the past 30 years has focused on endogenous and exogenous neuronal relays, but progress has been slow and the results often controversial. Treatments with stem cell-derived neuronal relays alone or together with functional electrical stimulation offer the possibility of improved repair of neuronal networks. In this review, we focus on approaches to recovery of motor function in paralyzed patients after severe SCI based on novel therapies such as implantation of stem cell-derived neuronal relays and functional electrical stimulation. Recent research progress offers hope that SCI patients will one day be able to recover motor function and sensory perception.
Collapse
Affiliation(s)
- Bi-Qin Lai
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Xiang Zeng
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China
| | - Wei-Tao Han
- Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Ming-Tian Che
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China
| | - Ying Ding
- Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Ge Li
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China
| | - Yuan-Shan Zeng
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China; Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China; Institute of Spinal Cord Injury, Sun Yat-sen University, Guangzhou, 510120, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China; Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan, School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
| |
Collapse
|
7
|
Hogan MK, Barber SM, Rao Z, Kondiles BR, Huang M, Steele WJ, Yu C, Horner PJ. A wireless spinal stimulation system for ventral activation of the rat cervical spinal cord. Sci Rep 2021; 11:14900. [PMID: 34290260 PMCID: PMC8295294 DOI: 10.1038/s41598-021-94047-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/24/2021] [Indexed: 11/09/2022] Open
Abstract
Electrical stimulation of the cervical spinal cord is gaining traction as a therapy following spinal cord injury; however, it is difficult to target the cervical motor region in a rodent using a non-penetrating stimulus compared with direct placement of intraspinal wire electrodes. Penetrating wire electrodes have been explored in rodent and pig models and, while they have proven beneficial in the injured spinal cord, the negative aspects of spinal parenchymal penetration (e.g., gliosis, neural tissue damage, and obdurate inflammation) are of concern when considering therapeutic potential. We therefore designed a novel approach for epidural stimulation of the rat spinal cord using a wireless stimulation system and ventral electrode array. Our approach allowed for preservation of mobility following surgery and was suitable for long term stimulation strategies in awake, freely functioning animals. Further, electrophysiology mapping of the ventral spinal cord revealed the ventral approach was suitable to target muscle groups of the rat forelimb and, at a single electrode lead position, different stimulation protocols could be applied to achieve unique activation patterns of the muscles of the forelimb.
Collapse
Affiliation(s)
- Matthew K Hogan
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, USA.
| | - Sean M Barber
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, USA
| | | | - Bethany R Kondiles
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, USA.,International Collaboration on Repair Discovories, University of British Columbia, Vancouver, Canada
| | - Meng Huang
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, USA
| | - William J Steele
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, USA
| | | | - Philip J Horner
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, USA
| |
Collapse
|
8
|
Pikov V, McCreery DB, Han M. Intraspinal stimulation with a silicon-based 3D chronic microelectrode array for bladder voiding in cats. J Neural Eng 2020; 17. [PMID: 33181490 PMCID: PMC8113353 DOI: 10.1088/1741-2552/abca13] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 11/12/2020] [Indexed: 12/31/2022]
Abstract
Objective. Bladder dysfunction is a significant and largely unaddressed problem for people living with spinal cord injury (SCI). Intermittent catheterization does not provide volitional control of micturition and has numerous side effects. Targeted electrical microstimulation of the spinal cord has been previously explored for restoring such volitional control in the animal model of experimental SCI. Here, we continue the development of the intraspinal microstimulation array technology to evaluate its ability to provide more focused and reliable bladder control in the feline animal model. Approach. For the first time, a mechanically robust intraspinal multisite silicon array was built using novel microfabrication processes to provide custom-designed tip geometry and 3D electrode distribution. Long-term implantation was performed in eight spinally intact animals for a period up to 6 months, targeting the dorsal gray commissure area in the S2 sacral cord that is known to be involved in the coordination between the bladder detrusor and the external urethral sphincter. Main results. About one third of the electrode sites in the that area produced micturition-related responses. The effectiveness of stimulation was further evaluated in one of eight animals after spinal cord transection (SCT). We observed increased bladder responsiveness to stimulation starting at 1 month post-transection, possibly due to supraspinal disinhibition of the spinal circuitry and/or hypertrophy and hyperexcitability of the spinal bladder afferents. Significance. 3D intraspinal microstimulation arrays can be chronically implanted and provide a beneficial effect on the bladder voiding in the intact spinal cord and after SCT. However, further studies are required to assess longer-term reliability and safety of the developed intraspinal microstimulation array prior to eventual human translation.
Collapse
Affiliation(s)
- Victor Pikov
- Medipace Inc, Pasadena, California, UNITED STATES
| | - Douglas B McCreery
- Neural Engineeiring Laboratory, Huntington Medical Research Institute, 734 Fairmount Avenue, Pasadena CA 91105, USA, Pasadena, California, 91105, UNITED STATES
| | - Martin Han
- Biomedical Engineering, University of Connecticut at Storrs , 260 Glenbrook Rd., Unit 3247, Storrs, Connecticut, 06269-3247, UNITED STATES
| |
Collapse
|
9
|
Dalrymple AN, Huynh M, Nayagam BA, Lee CD, Weiland GR, Petrossians A, J J, Iii W, Fallon JB, Shepherd RK. Electrochemical and biological characterization of thin-film platinum-iridium alloy electrode coatings: a chronic in vivo study. J Neural Eng 2020; 17:036012. [PMID: 32408281 DOI: 10.1088/1741-2552/ab933d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To evaluate the electrochemical properties, biological response, and surface characterization of an electrodeposited Platinum-Iridium (Pt-Ir) electrode coating on cochlear implants subjected to chronic stimulation in vivo. APPROACH Electrochemical impedance spectroscopy (EIS), charge storage capacity (CSC), charge injection limit (CIL), and voltage transient (VT) impedance were measured bench-top before and after implant and in vivo. Coated Pt-Ir and uncoated Pt electrode arrays were implanted into cochlea of normal hearing rats and stimulated for ∼4 h d, 5 d week-1 for 5 weeks at levels within the normal clinical range. Neural function was monitored using electrically-evoked auditory brainstem responses. After explant, the electrode surfaces were assessed, and cochleae examined histologically. MAIN RESULTS When measured on bench-top before and after stimulation, Pt-Ir coated electrodes had significantly lower VT impedance (p < 0.001) and significantly higher CSC (p < 0.001) and CIL (p < 0.001) compared to uncoated Pt electrodes. In vivo, the CSC and CIL of Pt-Ir were significantly higher than Pt throughout the implantation period (p= 0.047 and p< 0.001, respectively); however, the VT impedance (p= 0.3) was not. There was no difference in foreign body response between material cohorts, although cochleae implanted with coated electrodes contained small deposits of Pt-Ir. There was no evidence of increased neural loss or loss of neural function in either group. Surface examination revealed no Pt corrosion on any electrodes. SIGNIFICANCE Electrodeposited Pt-Ir electrodes demonstrated significant improvements in electrochemical performance on the bench-top and in vivo compared to uncoated Pt. Neural function and tissue response to Pt-Ir electrodes were not different from uncoated Pt, despite small deposits of Pt-Ir in the tissue capsule. Electrodeposited Pt-Ir coatings offer promise as an improved electrode coating for active neural prostheses.
Collapse
|
10
|
Dalrymple AN, Roszko DA, Sutton RS, Mushahwar VK. Pavlovian control of intraspinal microstimulation to produce over-ground walking. J Neural Eng 2020; 17:036002. [PMID: 32348970 DOI: 10.1088/1741-2552/ab8e8e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Neuromodulation technologies are increasingly used for improving function after neural injury. To achieve a symbiotic relationship between device and user, the device must augment remaining function, and independently adapt to day-to-day changes in function. The goal of this study was to develop predictive control strategies to produce over-ground walking in a model of hemisection spinal cord injury (SCI) using intraspinal microstimulation (ISMS). APPROACH Eight cats were anaesthetized and placed in a sling over a walkway. The residual function of a hemisection SCI was mimicked by manually moving one hind-limb through the walking cycle. ISMS targeted motor networks in the lumbosacral enlargement to activate muscles in the other, presumably 'paralyzed' limb, using low levels of current (<130 μA). Four people took turns to move the 'intact' limb, generating four different walking styles. Two control strategies, which used ground reaction force and angular velocity information about the manually moved 'intact' limb to control the timing of the transitions of the 'paralyzed' limb through the step cycle, were compared. The first strategy used thresholds on the raw sensor values to initiate transitions. The second strategy used reinforcement learning and Pavlovian control to learn predictions about the sensor values. Thresholds on the predictions were then used to initiate transitions. MAIN RESULTS Both control strategies were able to produce alternating, over-ground walking. Transitions based on raw sensor values required manual tuning of thresholds for each person to produce walking, whereas Pavlovian control did not. Learning occurred quickly during walking: predictions of the sensor signals were learned rapidly, initiating correct transitions after ≤4 steps. Pavlovian control was resilient to different walking styles and different cats, and recovered from induced mistakes during walking. SIGNIFICANCE This work demonstrates, for the first time, that Pavlovian control can augment remaining function and facilitate personalized walking with minimal tuning requirements.
Collapse
Affiliation(s)
- Ashley N Dalrymple
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada. Sensory Motor Adaptive Rehabilitation Technology (SMART) Network, University of Alberta, Edmonton, AB, Canada
| | | | | | | |
Collapse
|
11
|
Dalrymple AN, Robles UA, Huynh M, Nayagam BA, Green RA, Poole-Warren LA, Fallon JB, Shepherd RK. Electrochemical and biological performance of chronically stimulated conductive hydrogel electrodes. J Neural Eng 2020; 17:026018. [DOI: 10.1088/1741-2552/ab7cfc] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
12
|
Nagel SJ, Frizon L, Maiti T, Machado AG, Gillies GT, Helland L, Woodroffe RW, Howard MA, Wilson S. Contemporary Approaches to Preventing and Treating Infections of Novel Intrathecal Neurostimulation Devices. World Neurosurg 2019; 128:e397-e408. [DOI: 10.1016/j.wneu.2019.04.165] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 02/04/2023]
|