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Wang F, Chen X, Roelfsema PR. Comparison of electrical microstimulation artifact removal methods for high-channel-count prostheses. J Neurosci Methods 2024; 408:110169. [PMID: 38782123 DOI: 10.1016/j.jneumeth.2024.110169] [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: 10/17/2023] [Revised: 04/15/2024] [Accepted: 05/17/2024] [Indexed: 05/25/2024]
Abstract
BACKGROUND Neuroprostheses are used to electrically stimulate the brain, modulate neural activity and restore sensory and motor function following injury or disease, such as blindness, paralysis, and other movement and psychiatric disorders. Recordings are often made simultaneously with stimulation, allowing the monitoring of neural signals and closed-loop control of devices. However, stimulation-evoked artifacts may obscure neural activity, particularly when stimulation and recording sites are nearby. Several methods have been developed to remove stimulation artifacts, but it remains challenging to validate and compare these methods because the 'ground-truth' of the neuronal signals may be contaminated by artifacts. NEW METHOD Here, we delivered stimulation to the visual cortex via a high-channel-count prosthesis while recording neuronal activity and stimulation artifacts. We quantified the waveforms and temporal properties of stimulation artifacts from the cortical visual prosthesis (CVP) and used them to build a dataset, in which we simulated the neuronal activity and the stimulation artifacts. We illustrate how to use the simulated data to evaluate the performance of six software-based artifact removal methods (Template subtraction, Linear interpolation, Polynomial fitting, Exponential fitting, SALPA and ERAASR) in a CVP application scenario. RESULTS We here focused on stimulation artifacts caused by electrical stimulation through a high-channel-count cortical prosthesis device. We find that the Polynomial fitting and Exponential fitting methods outperform the other methods in recovering spikes and multi-unit activity. Linear interpolation and Template subtraction recovered the local-field potentials. CONCLUSION Polynomial fitting and Exponential fitting provided a good trade-off between the quality of the recovery of spikes and multi-unit activity (MUA) and the computational complexity for a cortical prosthesis.
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Affiliation(s)
- Feng Wang
- Department of Vision & Cognition, Netherlands Institute for Neuroscience (KNAW), Amsterdam 1105 BA, the Netherlands.
| | - Xing Chen
- Department of Ophthalmology, University of Pittsburgh School of Medicine, 203 Lothrop St, Pittsburgh, PA 15213, US.
| | - Pieter R Roelfsema
- Department of Vision & Cognition, Netherlands Institute for Neuroscience (KNAW), Amsterdam 1105 BA, the Netherlands; Department of Ophthalmology, University of Pittsburgh School of Medicine, 203 Lothrop St, Pittsburgh, PA 15213, US; Department of Integrative Neurophysiology, VU University, De Boelelaan 1085, Amsterdam 1081 HV, the Netherlands; Department of Neurosurgery, Academic Medical Centre, Postbus 22660, Amsterdam 1100 DD, the Netherlands; Laboratory of Visual Brain Therapy, Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris F-75012, France.
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Hong Y, Ryun S, Chung CK. Evoking artificial speech perception through invasive brain stimulation for brain-computer interfaces: current challenges and future perspectives. Front Neurosci 2024; 18:1428256. [PMID: 38988764 PMCID: PMC11234843 DOI: 10.3389/fnins.2024.1428256] [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: 05/06/2024] [Accepted: 06/10/2024] [Indexed: 07/12/2024] Open
Abstract
Encoding artificial perceptions through brain stimulation, especially that of higher cognitive functions such as speech perception, is one of the most formidable challenges in brain-computer interfaces (BCI). Brain stimulation has been used for functional mapping in clinical practices for the last 70 years to treat various disorders affecting the nervous system, including epilepsy, Parkinson's disease, essential tremors, and dystonia. Recently, direct electrical stimulation has been used to evoke various forms of perception in humans, ranging from sensorimotor, auditory, and visual to speech cognition. Successfully evoking and fine-tuning artificial perceptions could revolutionize communication for individuals with speech disorders and significantly enhance the capabilities of brain-computer interface technologies. However, despite the extensive literature on encoding various perceptions and the rising popularity of speech BCIs, inducing artificial speech perception is still largely unexplored, and its potential has yet to be determined. In this paper, we examine the various stimulation techniques used to evoke complex percepts and the target brain areas for the input of speech-like information. Finally, we discuss strategies to address the challenges of speech encoding and discuss the prospects of these approaches.
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Affiliation(s)
- Yirye Hong
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seokyun Ryun
- Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea
| | - Chun Kee Chung
- Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea
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Lešták J. Visual Neuroprosthesis - Stimulation of Visual Cortical Centers in The Brain. Design of Non-Invasive Transcranial Stimulation of Functional Neurons. CESKA A SLOVENSKA OFTALMOLOGIE : CASOPIS CESKE OFTALMOLOGICKE SPOLECNOSTI A SLOVENSKE OFTALMOLOGICKE SPOLECNOSTI 2024; 80:132-137. [PMID: 38413228 DOI: 10.31348/2024/2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
PURPOSE The purpose of the article is to present the history and current status of visual cortical neuroprostheses, and to present a new method of stimulating intact visual cortex cells. METHODS This paper contains an overview of the history and current status of visual cortex stimulation in severe visual impairment, but also highlights its shortcomings. These include mainly the stimulation of currently damaged cortical cells over a small area and, from a morphological point of view, possible damage to the stimulated neurons by the electrodes and their encapsulation by gliotic tissue. RESULTS The paper also presents a proposal for a new technology of image processing and its transformation into a form of non-invasive transcranial stimulation of undamaged parts of the brain, which is protected by a national and international patent. CONCLUSION The paper presents a comprehensive review of the current options for compensating for lost vision at the level of the cerebral cortex and a proposal for a new non-invasive method of stimulating the functional neurons of the visual cortex.
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Amaral L, Thomas P, Amedi A, Striem-Amit E. Longitudinal stability of individual brain plasticity patterns in blindness. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.01.565196. [PMID: 37986779 PMCID: PMC10659359 DOI: 10.1101/2023.11.01.565196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
The primary visual cortex (V1) in individuals born blind is engaged in a wide spectrum of tasks and sensory modalities, including audition, touch, language, and memory. This widespread involvement raises questions regarding the constancy of its role and whether it might exhibit flexibility in its function over time, connecting to diverse network functions in response to task-specific demands. This would suggest that reorganized V1 takes on a role similar to cognitive multiple-demand system regions. Alternatively, it is possible that the varying patterns of plasticity observed in the blind V1 can be attributed to individual factors, whereby different blind individuals recruit V1 for different functions, highlighting the immense idiosyncrasy of plasticity. In support of this second account, we have recently shown that V1 functional connectivity varies greatly across blind individuals. But do these represent stable individual patterns of plasticity or merely instantaneous changes, for a multiple-demand system now inhabiting V1? Here we tested if individual connectivity patterns from the visual cortex of blind individuals are stable over time. We show that over two years, fMRI functional connectivity from the primary visual cortex is unique and highly stable in a small sample of repeatedly sampled congenitally blind individuals. Further, using multivoxel pattern analysis, we demonstrate that the unique reorganization patterns of these individuals allow decoding of participant identity. Together with recent evidence for substantial individual differences in visual cortex connectivity, this indicates there may be a consistent role for the visual cortex in blindness, which may differ for each individual. Further, it suggests that the variability in visual reorganization in blindness across individuals could be used to seek stable neuromarkers for sight rehabilitation and assistive approaches.
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Affiliation(s)
- Lénia Amaral
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Peyton Thomas
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Amir Amedi
- Ivcher School of Psychology, The Institute for Brain, Mind and Technology, Reichman University, Herzliya, Israel
- The Ruth & Meir Rosenthal Brain Imaging Center, Reichman University, Herzliya, Israel
| | - Ella Striem-Amit
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20057, USA
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Karadima V, Pezaris EA, Pezaris JS. Attitudes of potential recipients toward emerging visual prosthesis technologies. Sci Rep 2023; 13:10963. [PMID: 37414798 PMCID: PMC10325978 DOI: 10.1038/s41598-023-36913-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 06/12/2023] [Indexed: 07/08/2023] Open
Abstract
With the advent of multiple visual prosthesis devices to treat blindness, the question of how potential patients view such interventions becomes important in order to understand the levels of expectation and acceptance, and the perceived risk-reward balance across the different device approaches. Building on previous work on single device approaches done with blind individuals in Chicago and Detroit, USA, Melbourne, Australia, and Bejing, China, we investigated attitudes in blind individuals in Athens, Greece with coverage expanded to three of the contemporary approaches, Retinal, Thalamic, and Cortical. We presented an informational lecture on the approaches, had potential participants fill out a preliminary Questionnaire 1, then organized selected subjects into focus groups for guided discussion on visual prostheses, and finally had these subjects fill out a more detailed Questionnaire 2. We report here the first quantitative data that compares multiple prosthesis approaches. Our primary findings are that for these potential patients, perceived risk continues to outweigh perceived benefits, with the Retinal approach having the least negative overall impression and the Cortical approach the most negative. Concerns about the quality of restored vision were primary. Factors that drove the choice of hypothetical participation in a clinical trial were age and years of blindness. Secondary factors focused on positive clinical outcomes. The focus groups served to swing the impressions of each approach from neutrality toward the extremes of a Likert scale, and shifted the overall willingness to participate in a clinical trial from neutral to negative. These results, coupled with informal assessment of audience questions after the informational lecture, suggest that a substantial improvement in performance over currently available devices will be necessary before visual prostheses gain wide acceptance.
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Affiliation(s)
- Vicky Karadima
- Multisensory and Temporal Processing Lab (MultiTimeLab), Department of Psychology, Panteion University of Social and Political Sciences, Athens, Greece
| | | | - John S Pezaris
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, USA.
- Department of Neurosurgery, Harvard Medical School, Boston, MA, USA.
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Chen X, Wang F, Kooijmans R, Klink PC, Boehler C, Asplund M, Roelfsema PR. Chronic stability of a neuroprosthesis comprising multiple adjacent Utah arrays in monkeys. J Neural Eng 2023; 20:036039. [PMID: 37386891 DOI: 10.1088/1741-2552/ace07e] [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: 03/17/2023] [Accepted: 06/21/2023] [Indexed: 07/01/2023]
Abstract
Objective. Electrical stimulation of visual cortex via a neuroprosthesis induces the perception of dots of light ('phosphenes'), potentially allowing recognition of simple shapes even after decades of blindness. However, restoration of functional vision requires large numbers of electrodes, and chronic, clinical implantation of intracortical electrodes in the visual cortex has only been achieved using devices of up to 96 channels. We evaluated the efficacy and stability of a 1024-channel neuroprosthesis system in non-human primates (NHPs) over more than 3 years to assess its suitability for long-term vision restoration.Approach.We implanted 16 microelectrode arrays (Utah arrays) consisting of 8 × 8 electrodes with iridium oxide tips in the primary visual cortex (V1) and visual area 4 (V4) of two sighted macaques. We monitored the animals' health and measured electrode impedances and neuronal signal quality by calculating signal-to-noise ratios of visually driven neuronal activity, peak-to-peak voltages of the waveforms of action potentials, and the number of channels with high-amplitude signals. We delivered cortical microstimulation and determined the minimum current that could be perceived, monitoring the number of channels that successfully yielded phosphenes. We also examined the influence of the implant on a visual task after 2-3 years of implantation and determined the integrity of the brain tissue with a histological analysis 3-3.5 years post-implantation.Main results. The monkeys remained healthy throughout the implantation period and the device retained its mechanical integrity and electrical conductivity. However, we observed decreasing signal quality with time, declining numbers of phosphene-evoking electrodes, decreases in electrode impedances, and impaired performance on a visual task at visual field locations corresponding to implanted cortical regions. Current thresholds increased with time in one of the two animals. The histological analysis revealed encapsulation of arrays and cortical degeneration. Scanning electron microscopy on one array revealed degradation of IrOxcoating and higher impedances for electrodes with broken tips.Significance. Long-term implantation of a high-channel-count device in NHP visual cortex was accompanied by deformation of cortical tissue and decreased stimulation efficacy and signal quality over time. We conclude that improvements in device biocompatibility and/or refinement of implantation techniques are needed before future clinical use is feasible.
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Affiliation(s)
- Xing Chen
- Department of Vision and Cognition, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
- Department of Ophthalmology, University of Pittsburgh School of Medicine, 1622 Locust St, Pittsburgh, PA 15219, United States of America
| | - Feng Wang
- Department of Vision and Cognition, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - Roxana Kooijmans
- Department of Vision and Cognition, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - Peter Christiaan Klink
- Department of Vision and Cognition, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
- Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, The Netherlands
- Laboratory of Visual Brain Therapy, Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris F-75012, France
| | - Christian Boehler
- Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Georges-Köhler-Allee 201, 79110 Freiburg, Germany
| | - Maria Asplund
- Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Georges-Köhler-Allee 201, 79110 Freiburg, Germany
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Albertstraße 19, 79104 Freiburg, Germany
- Chalmers University of Technology, Chalmersplatsen 4, 412 96 Gothenburg, Sweden
| | - Pieter Roelf Roelfsema
- Department of Vision and Cognition, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
- Laboratory of Visual Brain Therapy, Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris F-75012, France
- Department of Integrative Neurophysiology, VU University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
- Department of Psychiatry, Academic Medical Center, Postbus 22660, 1100 DD Amsterdam, The Netherlands
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Grani F, Soto-Sánchez C, Fimia A, Fernández E. Toward a personalized closed-loop stimulation of the visual cortex: Advances and challenges. Front Cell Neurosci 2022; 16:1034270. [PMID: 36582211 PMCID: PMC9792612 DOI: 10.3389/fncel.2022.1034270] [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: 09/01/2022] [Accepted: 11/24/2022] [Indexed: 12/15/2022] Open
Abstract
Current cortical visual prosthesis approaches are primarily unidirectional and do not consider the feed-back circuits that exist in just about every part of the nervous system. Herein, we provide a brief overview of some recent developments for better controlling brain stimulation and present preliminary human data indicating that closed-loop strategies could considerably enhance the effectiveness, safety, and long-term stability of visual cortex stimulation. We propose that the development of improved closed-loop strategies may help to enhance our capacity to communicate with the brain.
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Affiliation(s)
- Fabrizio Grani
- Institute of Bioengineering, Universidad Miguel Hernández de Elche, Elche, Spain
| | - Cristina Soto-Sánchez
- Institute of Bioengineering, Universidad Miguel Hernández de Elche, Elche, Spain,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain
| | - Antonio Fimia
- Departamento de Ciencia de Materiales, Óptica y Tecnología Electrónica, Universidad Miguel Hernández de Elche, Elche, Spain
| | - Eduardo Fernández
- Institute of Bioengineering, Universidad Miguel Hernández de Elche, Elche, Spain,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain,*Correspondence: Eduardo Fernández,
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