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Slack JC, Zeiser SL, Yadav AP. The role of stimulus periodicity on spinal cord stimulation-induced artificial sensations in rodents. J Neural Eng 2024; 21:026003. [PMID: 38382104 PMCID: PMC10912903 DOI: 10.1088/1741-2552/ad2b89] [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: 09/24/2023] [Revised: 01/26/2024] [Accepted: 02/21/2024] [Indexed: 02/23/2024]
Abstract
Objective.Sensory feedback is critical for effectively controlling brain-machine interfaces and neuroprosthetic devices. Spinal cord stimulation (SCS) is proposed as a technique to induce artificial sensory perceptions in rodents, monkeys, and humans. However, to realize the full potential of SCS as a sensory neuroprosthetic technology, a better understanding of the effect of SCS pulse train parameter changes on sensory detection and discrimination thresholds is necessary.Approach.Here we investigated whether stimulation periodicity impacts rats' ability to detect and discriminate SCS-induced perceptions at different frequencies.Main results.By varying the coefficient of variation (CV) of interstimulus pulse interval, we showed that at lower frequencies, rats could detect highly aperiodic SCS pulse trains at lower amplitudes (i.e. decreased detection thresholds). Furthermore, rats learned to discriminate stimuli with subtle differences in periodicity, and the just-noticeable differences from a highly aperiodic stimulus were smaller than those from a periodic stimulus.Significance.These results demonstrate that the temporal structure of an SCS pulse train is an integral parameter for modulating sensory feedback in neuroprosthetic applications.
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Affiliation(s)
- Jacob C Slack
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, United States of America
| | - Sidnee L Zeiser
- Department of Biomedical Engineering, Purdue University Indianapolis, Indianapolis, IN, United States of America
| | - Amol P Yadav
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, United States of America
- Department of Neurosurgery, UNC School of Medicine, Chapel Hill, NC, United States of America
- Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
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2
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Lyreskog DM, Zohny H, Savulescu J, Singh I. Merging Minds: The Conceptual and Ethical Impacts of Emerging Technologies for Collective Minds. NEUROETHICS-NETH 2023; 16:12. [PMID: 37009261 PMCID: PMC10050050 DOI: 10.1007/s12152-023-09516-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 02/26/2023] [Indexed: 03/30/2023]
Abstract
AbstractA growing number of technologies are currently being developed to improve and distribute thinking and decision-making. Rapid progress in brain-to-brain interfacing and swarming technologies promises to transform how we think about collective and collaborative cognitive tasks across domains, ranging from research to entertainment, and from therapeutics to military applications. As these tools continue to improve, we are prompted to monitor how they may affect our society on a broader level, but also how they may reshape our fundamental understanding of agency, responsibility, and other key concepts of our moral landscape.In this paper we take a closer look at this class of technologies – Technologies for Collective Minds – to see not only how their implementation may react with commonly held moral values, but also how they challenge our underlying concepts of what constitutes collective or individual agency. We argue that prominent contemporary frameworks for understanding collective agency and responsibility are insufficient in terms of accurately describing the relationships enabled by Technologies for Collective Minds, and that they therefore risk obstructing ethical analysis of the implementation of these technologies in society. We propose a more multidimensional approach to better understand this set of technologies, and to facilitate future research on the ethics of Technologies for Collective Minds.
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Affiliation(s)
- David M. Lyreskog
- Department of Psychiatry, Warneford Hospital, University of Oxford, Warneford Ln, Oxford, OX3 7JX UK
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, Oxford, UK
- Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
| | - Hazem Zohny
- Department of Psychiatry, Warneford Hospital, University of Oxford, Warneford Ln, Oxford, OX3 7JX UK
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, Oxford, UK
- Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
| | - Julian Savulescu
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, Oxford, UK
- Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
- Centre for Biomedical Ethics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Murdoch Children’s Research Institute, Melbourne, Australia
- University of Melbourne, Melbourne, Australia
| | - Ilina Singh
- Department of Psychiatry, Warneford Hospital, University of Oxford, Warneford Ln, Oxford, OX3 7JX UK
- Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
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Zuccaroli I, Lucke-Wold B, Palla A, Eremiev A, Sorrentino Z, Zakare-Fagbamila R, McNulty J, Christie C, Chandra V, Mampre D. Neural Bypasses: Literature Review and Future Directions in Developing Artificial Neural Connections. OBM NEUROBIOLOGY 2023; 7:158. [PMID: 36908763 PMCID: PMC9997488 DOI: 10.21926/obm.neurobiol.2301158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Reported neuro-modulation schemes in the literature are typically classified as closed-loop or open-loop. A novel group of recently developed neuro-modulation devices may be better described as a neural bypass, which attempts to transmit neural data from one location of the nervous system to another. The most common form of neural bypasses in the literature utilize EEG recordings of cortical information paired with functional electrical stimulation for effector muscle output, most commonly for assistive applications and rehabilitation in spinal cord injury or stroke. Other neural bypass locations that have also been described, or may soon be in development, include cortical-spinal bypasses, cortical-cortical bypasses, autonomic bypasses, peripheral-central bypasses, and inter-subject bypasses. The most common recording devices include EEG, ECoG, and microelectrode arrays, while stimulation devices include both invasive and noninvasive electrodes. Several devices are in development to improve the temporal and spatial resolution and biocompatibility for neuronal recording and stimulation. A major barrier to entry includes neuroplasticity and current decoding mechanisms that regularly require retraining. Neural bypasses are a unique class of neuro-modulation. Continued advancement of neural recording and stimulating devices with high spatial and temporal resolution, combined with decoding mechanisms uninhibited by neuroplasticity, can expand the therapeutic capability of neural bypassing. Overall, neural bypasses are a promising modality to improve the treatment of common neurologic disorders, including stroke, spinal cord injury, peripheral nerve injury, brain injury and more.
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Affiliation(s)
| | | | | | - Alexander Eremiev
- Department of Neurosurgery, New York University School of Medicine, New York, USA
| | | | | | - Jack McNulty
- Department of Neurosurgery, University of Iowa, Iowa City, IA, USA
| | - Carlton Christie
- Department of Neurosurgery, University of Florida, Gainesville, USA
| | - Vyshak Chandra
- Department of Neurosurgery, University of Florida, Gainesville, USA
| | - David Mampre
- Johns Hopkins University, Baltimore, USA
- Department of Neurosurgery, University of Florida, Gainesville, USA
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4
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Shome S, Talukdar AD, Upadhyaya H. Antibacterial activity of curcumin and its essential nanoformulations against some clinically important bacterial pathogens: A comprehensive review. Biotechnol Appl Biochem 2022; 69:2357-2386. [PMID: 34826356 DOI: 10.1002/bab.2289] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 11/22/2021] [Indexed: 12/27/2022]
Abstract
Multidrug-resistant bacterial infections can kill 700,000 individuals globally each year and is considered among the top 10 global health threats faced by humanity as the arsenal of antibiotics is becoming dry and alternate antibacterial molecule is in demand. Nanoparticles of curcumin exhibit appreciable broad-spectrum antibacterial activity using unique and novel mechanisms and thus the process deserves to be reviewed and further researched to clearly understand the mechanisms. Based on the antibiotic resistance, infection, and virulence potential, a list of clinically important bacteria was prepared after extensive literature survey and all recent reports on the antibacterial activity of curcumin and its nanoformulations as well as their mechanism of antibacterial action have been reviewed. Curcumin, nanocurcumin, and its nanocomposites with improved aqueous solubility and bioavailability are very potential, reliable, safe, and sustainable antibacterial molecule against clinically important bacterial species that uses multitarget mechanism such as inactivation of antioxidant enzyme, reactive oxygen species-mediated cellular damage, and inhibition of acyl-homoserine-lactone synthase necessary for quorum sensing and biofilm formation, thereby bypassing the mechanisms of bacterial antibiotic resistance. Nanoformulations of curcumin can thus be considered as a potential and sustainable antibacterial drug candidate to address the issue of antibiotic resistance.
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Affiliation(s)
- Soumitra Shome
- Ethnobotany and Medicinal Plants Research Laboratory, Department of Life Science and Bioinformatics, Assam University, Silchar, Assam, India
| | - Anupam Das Talukdar
- Ethnobotany and Medicinal Plants Research Laboratory, Department of Life Science and Bioinformatics, Assam University, Silchar, Assam, India
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Insausti-Delgado A, López-Larraz E, Nishimura Y, Ziemann U, Ramos-Murguialday A. Non-invasive brain-spine interface: Continuous control of trans-spinal magnetic stimulation using EEG. Front Bioeng Biotechnol 2022; 10:975037. [PMID: 36394044 PMCID: PMC9659618 DOI: 10.3389/fbioe.2022.975037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 09/23/2022] [Indexed: 08/22/2023] Open
Abstract
Brain-controlled neuromodulation has emerged as a promising tool to promote functional recovery in patients with motor disorders. Brain-machine interfaces exploit this neuromodulatory strategy and could be used for restoring voluntary control of lower limbs. In this work, we propose a non-invasive brain-spine interface (BSI) that processes electroencephalographic (EEG) activity to volitionally control trans-spinal magnetic stimulation (ts-MS), as an approach for lower-limb neurorehabilitation. This novel platform allows to contingently connect motor cortical activation during leg motor imagery with the activation of leg muscles via ts-MS. We tested this closed-loop system in 10 healthy participants using different stimulation conditions. This BSI efficiently removed stimulation artifacts from EEG regardless of ts-MS intensity used, allowing continuous monitoring of cortical activity and real-time closed-loop control of ts-MS. Our BSI induced afferent and efferent evoked responses, being this activation ts-MS intensity-dependent. We demonstrated the feasibility, safety and usability of this non-invasive BSI. The presented system represents a novel non-invasive means of brain-controlled neuromodulation and opens the door towards its integration as a therapeutic tool for lower-limb rehabilitation.
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Affiliation(s)
- Ainhoa Insausti-Delgado
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- International Max Planck Research School (IMPRS) for Cognitive and Systems Neuroscience, Tübingen, Germany
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- TECNALIA, Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián, Spain
| | - Eduardo López-Larraz
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Bitbrain, Zaragoza, Spain
| | - Yukio Nishimura
- Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Ulf Ziemann
- Department of Neurology and Stroke, University of Tübingen, Tübingen, Germany
- Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Ander Ramos-Murguialday
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- TECNALIA, Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián, Spain
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6
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Russman SM, Cleary DR, Tchoe Y, Bourhis AM, Stedelin B, Martin J, Brown EC, Zhang X, Kawamoto A, Ryu WHA, Raslan AM, Ciacci JD, Dayeh SA. Constructing 2D maps of human spinal cord activity and isolating the functional midline with high-density microelectrode arrays. Sci Transl Med 2022; 14:eabq4744. [PMID: 36170445 DOI: 10.1126/scitranslmed.abq4744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Intraoperative neuromonitoring (IONM) is a widely used practice in spine surgery for early detection and minimization of neurological injury. IONM is most commonly conducted by indirectly recording motor and somatosensory evoked potentials from either muscles or the scalp, which requires large-amplitude electrical stimulation and provides limited spatiotemporal information. IONM may inform of inadvertent events during neurosurgery after they occur, but it does not guide safe surgical procedures when the anatomy of the diseased spinal cord is distorted. To overcome these limitations and to increase our understanding of human spinal cord neurophysiology, we applied a microelectrode array with hundreds of channels to the exposed spinal cord during surgery and resolved spatiotemporal dynamics with high definition. We used this method to construct two-dimensional maps of responsive channels and define with submillimeter precision the electrophysiological midline of the spinal cord. The high sensitivity of our microelectrode array allowed us to record both epidural and subdural responses at stimulation currents that are well below those used clinically and to resolve postoperative evoked potentials when IONM could not. Together, these advances highlight the potential of our microelectrode arrays to capture previously unexplored spinal cord neural activity and its spatiotemporal dynamics at high resolution, offering better electrophysiological markers that can transform IONM.
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Affiliation(s)
- Samantha M Russman
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.,Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Daniel R Cleary
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA.,Department of Neurosurgery, University of California, San Diego, La Jolla, CA 92093, USA
| | - Youngbin Tchoe
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Andrew M Bourhis
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Brittany Stedelin
- Department of Neurosurgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Joel Martin
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA.,Department of Neurosurgery, University of California, San Diego, La Jolla, CA 92093, USA
| | - Erik C Brown
- Department of Neurosurgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Xinlian Zhang
- Division of Biostatistics and Bioinformatics, Herbert Wertheim School of Public Health, University of California, San Diego, La Jolla, CA 92093, USA
| | - Aaron Kawamoto
- Department of Neurosurgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Won Hyung A Ryu
- Department of Neurosurgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ahmed M Raslan
- Department of Neurosurgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Joseph D Ciacci
- Department of Neurosurgery, University of California, San Diego, La Jolla, CA 92093, USA
| | - Shadi A Dayeh
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.,Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA
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7
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Shokur S, Mazzoni A, Schiavone G, Weber DJ, Micera S. A modular strategy for next-generation upper-limb sensory-motor neuroprostheses. MED 2021; 2:912-937. [DOI: 10.1016/j.medj.2021.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 04/28/2021] [Accepted: 05/10/2021] [Indexed: 02/06/2023]
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Rahimpour S, Gaztanaga W, Yadav AP, Chang SJ, Krucoff MO, Cajigas I, Turner DA, Wang DD. Freezing of Gait in Parkinson's Disease: Invasive and Noninvasive Neuromodulation. Neuromodulation 2021; 24:829-842. [PMID: 33368872 PMCID: PMC8233405 DOI: 10.1111/ner.13347] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/01/2020] [Accepted: 12/01/2020] [Indexed: 01/23/2023]
Abstract
INTRODUCTION Freezing of gait (FoG) is one of the most disabling yet poorly understood symptoms of Parkinson's disease (PD). FoG is an episodic gait pattern characterized by the inability to step that occurs on initiation or turning while walking, particularly with perception of tight surroundings. This phenomenon impairs balance, increases falls, and reduces the quality of life. MATERIALS AND METHODS Clinical-anatomical correlations, electrophysiology, and functional imaging have generated several mechanistic hypotheses, ranging from the most distal (abnormal central pattern generators of the spinal cord) to the most proximal (frontal executive dysfunction). Here, we review the neuroanatomy and pathophysiology of gait initiation in the context of FoG, and we discuss targets of central nervous system neuromodulation and their outcomes so far. The PubMed database was searched using these key words: neuromodulation, freezing of gait, Parkinson's disease, and gait disorders. CONCLUSION Despite these investigations, the pathogenesis of this process remains poorly understood. The evidence presented in this review suggests FoG to be a heterogenous phenomenon without a single unifying pathologic target. Future studies rigorously assessing targets as well as multimodal approaches will be essential to define the next generation of therapeutic treatments.
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Affiliation(s)
- Shervin Rahimpour
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, USA
| | - Wendy Gaztanaga
- Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Amol P. Yadav
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Stephano J. Chang
- Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Max O. Krucoff
- Department of Neurosurgery, Medical College of Wisconsin, Wauwatosa, WI, USA
- Department of Biomedical Engineering, Marquette University & Medical College of Wisconsin, Milwaukee, WI, USA
| | - Iahn Cajigas
- Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Dennis A. Turner
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, USA
- Departments of Neurobiology and Biomedical Engineering, Duke University, Durham, NC, USA
| | - Doris D. Wang
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
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Yadav AP, Li S, Krucoff MO, Lebedev MA, Abd-El-Barr MM, Nicolelis MAL. Generating artificial sensations with spinal cord stimulation in primates and rodents. Brain Stimul 2021; 14:825-836. [PMID: 34015518 DOI: 10.1016/j.brs.2021.04.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 04/01/2021] [Accepted: 04/30/2021] [Indexed: 11/17/2022] Open
Abstract
For patients who have lost sensory function due to a neurological injury such as spinal cord injury (SCI), stroke, or amputation, spinal cord stimulation (SCS) may provide a mechanism for restoring somatic sensations via an intuitive, non-visual pathway. Inspired by this vision, here we trained rhesus monkeys and rats to detect and discriminate patterns of epidural SCS. Thereafter, we constructed psychometric curves describing the relationship between different SCS parameters and the animal's ability to detect SCS and/or changes in its characteristics. We found that the stimulus detection threshold decreased with higher frequency, longer pulse-width, and increasing duration of SCS. Moreover, we found that monkeys were able to discriminate temporally- and spatially-varying patterns (i.e. variations in frequency and location) of SCS delivered through multiple electrodes. Additionally, sensory discrimination of SCS-induced sensations in rats obeyed Weber's law of just-noticeable differences. These findings suggest that by varying SCS intensity, temporal pattern, and location different sensory experiences can be evoked. As such, we posit that SCS can provide intuitive sensory feedback in neuroprosthetic devices.
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Affiliation(s)
- Amol P Yadav
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA; Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | - Shuangyan Li
- Department of Neurobiology, Duke University, Durham, NC, 27710, USA; State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Tianjin, 300130, PR China; Tianjin Key Laboratory Bioelectromagnetic Technology and Intelligent Health, Hebei University of Technology, Tianjin, 300130, PR China
| | - Max O Krucoff
- Department of Neurosurgery, Medical College of Wisconsin & Froedtert Health, Wauwatosa, WI, 53226, USA; Department of Biomedical Engineering, Marquette University & Medical College of Wisconsin, Milwaukee, WI, 53233, USA
| | - Mikhail A Lebedev
- Center for Neuroengineering, Duke University, Durham, NC, 27710, USA; Skolkovo Institute of Science and Technology, 30 Bolshoy Bulvar, Moscow, 143026, Russia
| | | | - Miguel A L Nicolelis
- Department of Neurosurgery, Duke University, Durham, NC, 27710, USA; Center for Neuroengineering, Duke University, Durham, NC, 27710, USA; Department of Neurobiology, Duke University, Durham, NC, 27710, USA; Department of Biomedical Engineering, Duke University, Durham, NC, 27710, USA; Department of Psychology and Neuroscience, Duke University, Durham, NC, 27710, USA; Department of Neurology, Duke University, Durham, NC, 27710, USA; Edmond and Lily Safra International Institute of Neuroscience, Natal, 59066060, Brazil
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10
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Yadav AP, Li S, Krucoff MO, Lebedev MA, Abd-el-barr MM, Nicolelis MA. Generating Artificial Sensations with Spinal Cord Stimulation in Primates and Rodents.. [DOI: 10.1101/2020.05.09.085647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
AbstractFor patients who have lost sensory function due to a neurological injury such as spinal cord injury (SCI), stroke, or amputation, spinal cord stimulation (SCS) may provide a mechanism for restoring somatic sensations via an intuitive, non-visual pathway. Inspired by this vision, here we trained rhesus monkeys and rats to detect and discriminate patterns of epidural SCS. Thereafter, we constructed psychometric curves describing the relationship between different SCS parameters and the animal’s ability to detect SCS and/or changes in its characteristics. We found that the stimulus detection threshold decreased with higher frequency, longer pulse-width, and increasing duration of SCS. Moreover, we found that monkeys were able to discriminate temporally- and spatially-varying patterns (i.e. variations in frequency and location) of SCS delivered through multiple electrodes. Additionally, sensory discrimination of SCS-induced sensations in rats obeyed Weber’s law of just noticeable differences. These findings suggest that by varying SCS intensity, temporal pattern, and location different sensory experiences can be evoked. As such, we posit that SCS can provide intuitive sensory feedback in neuroprosthetic devices.
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11
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Loutit AJ, Potas JR. Restoring Somatosensation: Advantages and Current Limitations of Targeting the Brainstem Dorsal Column Nuclei Complex. Front Neurosci 2020; 14:156. [PMID: 32184706 PMCID: PMC7058659 DOI: 10.3389/fnins.2020.00156] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 02/10/2020] [Indexed: 12/12/2022] Open
Abstract
Current neural prostheses can restore limb movement to tetraplegic patients by translating brain signals coding movements to control a variety of actuators. Fast and accurate somatosensory feedback is essential for normal movement, particularly dexterous tasks, but is currently lacking in motor neural prostheses. Attempts to restore somatosensory feedback have largely focused on cortical stimulation which, thus far, have succeeded in eliciting minimal naturalistic sensations. Yet, a question that deserves more attention is whether the cortex is the best place to activate the central nervous system to restore somatosensation. Here, we propose that the brainstem dorsal column nuclei are an ideal alternative target to restore somatosensation. We review some of the recent literature investigating the dorsal column nuclei functional organization and neurophysiology and highlight some of the advantages and limitations of the dorsal column nuclei as a future neural prosthetic target. Recent evidence supports the dorsal column nuclei as a potential neural prosthetic target, but also identifies several gaps in our knowledge as well as potential limitations which need to be addressed before such a goal can become reality.
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Affiliation(s)
| | - Jason R. Potas
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
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