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Manero A, Rivera V, Fu Q, Schwartzman JD, Prock-Gibbs H, Shah N, Gandhi D, White E, Crawford KE, Coathup MJ. Emerging Medical Technologies and Their Use in Bionic Repair and Human Augmentation. Bioengineering (Basel) 2024; 11:695. [PMID: 39061777 PMCID: PMC11274085 DOI: 10.3390/bioengineering11070695] [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: 06/13/2024] [Revised: 07/04/2024] [Accepted: 07/07/2024] [Indexed: 07/28/2024] Open
Abstract
As both the proportion of older people and the length of life increases globally, a rise in age-related degenerative diseases, disability, and prolonged dependency is projected. However, more sophisticated biomedical materials, as well as an improved understanding of human disease, is forecast to revolutionize the diagnosis and treatment of conditions ranging from osteoarthritis to Alzheimer's disease as well as impact disease prevention. Another, albeit quieter, revolution is also taking place within society: human augmentation. In this context, humans seek to improve themselves, metamorphosing through self-discipline or more recently, through use of emerging medical technologies, with the goal of transcending aging and mortality. In this review, and in the pursuit of improved medical care following aging, disease, disability, or injury, we first highlight cutting-edge and emerging materials-based neuroprosthetic technologies designed to restore limb or organ function. We highlight the potential for these technologies to be utilized to augment human performance beyond the range of natural performance. We discuss and explore the growing social movement of human augmentation and the idea that it is possible and desirable to use emerging technologies to push the boundaries of what it means to be a healthy human into the realm of superhuman performance and intelligence. This potential future capability is contrasted with limitations in the right-to-repair legislation, which may create challenges for patients. Now is the time for continued discussion of the ethical strategies for research, implementation, and long-term device sustainability or repair.
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Affiliation(s)
- Albert Manero
- Limbitless Solutions, University of Central Florida, 12703 Research Parkway, Suite 100, Orlando, FL 32826, USA (V.R.)
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA; (Q.F.); (K.E.C.)
| | - Viviana Rivera
- Limbitless Solutions, University of Central Florida, 12703 Research Parkway, Suite 100, Orlando, FL 32826, USA (V.R.)
| | - Qiushi Fu
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA; (Q.F.); (K.E.C.)
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - Jonathan D. Schwartzman
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA; (J.D.S.); (H.P.-G.); (N.S.); (D.G.); (E.W.)
| | - Hannah Prock-Gibbs
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA; (J.D.S.); (H.P.-G.); (N.S.); (D.G.); (E.W.)
| | - Neel Shah
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA; (J.D.S.); (H.P.-G.); (N.S.); (D.G.); (E.W.)
| | - Deep Gandhi
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA; (J.D.S.); (H.P.-G.); (N.S.); (D.G.); (E.W.)
| | - Evan White
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA; (J.D.S.); (H.P.-G.); (N.S.); (D.G.); (E.W.)
| | - Kaitlyn E. Crawford
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA; (Q.F.); (K.E.C.)
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - Melanie J. Coathup
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA; (Q.F.); (K.E.C.)
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA; (J.D.S.); (H.P.-G.); (N.S.); (D.G.); (E.W.)
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Cavallo A, Neumann WJ. Dopaminergic reinforcement in the motor system: Implications for Parkinson's disease and deep brain stimulation. Eur J Neurosci 2024; 59:457-472. [PMID: 38178558 DOI: 10.1111/ejn.16222] [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: 09/19/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 01/06/2024]
Abstract
Millions of people suffer from dopamine-related disorders spanning disturbances in movement, cognition and emotion. These changes are often attributed to changes in striatal dopamine function. Thus, understanding how dopamine signalling in the striatum and basal ganglia shapes human behaviour is fundamental to advancing the treatment of affected patients. Dopaminergic neurons innervate large-scale brain networks, and accordingly, many different roles for dopamine signals have been proposed, such as invigoration of movement and tracking of reward contingencies. The canonical circuit architecture of cortico-striatal loops sparks the question, of whether dopamine signals in the basal ganglia serve an overarching computational principle. Such a holistic understanding of dopamine functioning could provide new insights into symptom generation in psychiatry to neurology. Here, we review the perspective that dopamine could bidirectionally control neural population dynamics, increasing or decreasing their strength and likelihood to reoccur in the future, a process previously termed neural reinforcement. We outline how the basal ganglia pathways could drive strengthening and weakening of circuit dynamics and discuss the implication of this hypothesis on the understanding of motor signs of Parkinson's disease (PD), the most frequent dopaminergic disorder. We propose that loss of dopamine in PD may lead to a pathological brain state where repetition of neural activity leads to weakening and instability, possibly explanatory for the fact that movement in PD deteriorates with repetition. Finally, we speculate on how therapeutic interventions such as deep brain stimulation may be able to reinstate reinforcement signals and thereby improve treatment strategies for PD in the future.
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Affiliation(s)
- Alessia Cavallo
- Movement Disorder and Neuromodulation Unit, Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Wolf-Julian Neumann
- Movement Disorder and Neuromodulation Unit, Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
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Aweidah H, Xi Z, Sahel JA, Byrne LC. PRPF31-retinitis pigmentosa: Challenges and opportunities for clinical translation. Vision Res 2023; 213:108315. [PMID: 37714045 PMCID: PMC10872823 DOI: 10.1016/j.visres.2023.108315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 09/17/2023]
Abstract
Mutations in pre-mRNA processing factor 31 cause autosomal dominant retinitis pigmentosa (PRPF31-RP), for which there is currently no efficient treatment, making this disease a prime target for the development of novel therapeutic strategies. PRPF31-RP exhibits incomplete penetrance due to haploinsufficiency, in which reduced levels of gene expression from the mutated allele result in disease. A variety of model systems have been used in the investigation of disease etiology and therapy development. In this review, we discuss recent advances in both in vivo and in vitro model systems, evaluating their advantages and limitations in the context of therapy development for PRPF31-RP. Additionally, we describe the latest approaches for treatment, including AAV-mediated gene augmentation, genome editing, and late-stage therapies such as optogenetics, cell transplantation, and retinal prostheses.
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Affiliation(s)
- Hamzah Aweidah
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Zhouhuan Xi
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Ophthalmology, Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - José-Alain Sahel
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Leah C Byrne
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
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4
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Yang R, Zhao P, Wang L, Feng C, Peng C, Wang Z, Zhang Y, Shen M, Shi K, Weng S, Dong C, Zeng F, Zhang T, Chen X, Wang S, Wang Y, Luo Y, Chen Q, Chen Y, Jiang C, Jia S, Yu Z, Liu J, Wang F, Jiang S, Xu W, Li L, Wang G, Mo X, Zheng G, Chen A, Zhou X, Jiang C, Yuan Y, Yan B, Zhang J. Assessment of visual function in blind mice and monkeys with subretinally implanted nanowire arrays as artificial photoreceptors. Nat Biomed Eng 2023:10.1038/s41551-023-01137-8. [PMID: 37996614 DOI: 10.1038/s41551-023-01137-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 10/17/2023] [Indexed: 11/25/2023]
Abstract
Retinal prostheses could restore image-forming vision in conditions of photoreceptor degeneration. However, contrast sensitivity and visual acuity are often insufficient. Here we report the performance, in mice and monkeys with induced photoreceptor degeneration, of subretinally implanted gold-nanoparticle-coated titania nanowire arrays providing a spatial resolution of 77.5 μm and a temporal resolution of 3.92 Hz in ex vivo retinas (as determined by patch-clamp recording of retinal ganglion cells). In blind mice, the arrays allowed for the detection of drifting gratings and flashing objects at light-intensity thresholds of 15.70-18.09 μW mm-2, and offered visual acuities of 0.3-0.4 cycles per degree, as determined by recordings of visually evoked potentials and optomotor-response tests. In monkeys, the arrays were stable for 54 weeks, allowed for the detection of a 10-μW mm-2 beam of light (0.5° in beam angle) in visually guided saccade experiments, and induced plastic changes in the primary visual cortex, as indicated by long-term in vivo calcium imaging. Nanomaterials as artificial photoreceptors may ameliorate visual deficits in patients with photoreceptor degeneration.
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Affiliation(s)
- Ruyi Yang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Peng Zhao
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Liyang Wang
- Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, P. R. China
| | - Chenli Feng
- Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, P. R. China
| | - Chen Peng
- Laboratory of Advanced Materials, Department of Chemistry, Fudan University, Shanghai, P. R. China
| | - Zhexuan Wang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Yingying Zhang
- Key Laboratory of Brain Functional Genomics (Ministry of Education), East China Normal University, Shanghai, P. R. China
| | - Minqian Shen
- Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, P. R. China
| | - Kaiwen Shi
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Shijun Weng
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Chunqiong Dong
- Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, P. R. China
| | - Fu Zeng
- Key Laboratory of Brain Functional Genomics (Ministry of Education), East China Normal University, Shanghai, P. R. China
| | - Tianyun Zhang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Xingdong Chen
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Shuiyuan Wang
- Shanghai Key Lab for Future Computing Hardware and System, School of Microelectronics, Fudan University, Shanghai, P. R. China
| | - Yiheng Wang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Yuanyuan Luo
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Qingyuan Chen
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Yuqing Chen
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Chengyong Jiang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Shanshan Jia
- School of Computer Science, Institute for Artificial Intelligence, Peking University, Beijing, P.R. China
| | - Zhaofei Yu
- School of Computer Science, Institute for Artificial Intelligence, Peking University, Beijing, P.R. China
| | - Jian Liu
- School of Computer Science, University of Birmingham, Birmingham, UK
| | - Fei Wang
- Department of Hand Surgery, the National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, P. R. China
| | - Su Jiang
- Department of Hand Surgery, the National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, P. R. China
| | - Wendong Xu
- Department of Hand Surgery, the National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, P. R. China
- Department of Hand and Upper Extremity Surgery, Jing'an District Central Hospital, Fudan University, Shanghai, P.R. China
| | - Liang Li
- Center of Brain Sciences, Beijing Institute of Basic Medical Sciences, Beijing, P. R. China
| | - Gang Wang
- Center of Brain Sciences, Beijing Institute of Basic Medical Sciences, Beijing, P. R. China
| | - Xiaofen Mo
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Gengfeng Zheng
- Laboratory of Advanced Materials, Department of Chemistry, Fudan University, Shanghai, P. R. China
| | - Aihua Chen
- Key Laboratory of Brain Functional Genomics (Ministry of Education), East China Normal University, Shanghai, P. R. China
| | - Xingtao Zhou
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China
| | - Chunhui Jiang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China.
| | - Yuanzhi Yuan
- Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, P. R. China.
- Zhongshan Hospital (Xiamen), Fudan University, Xiamen, P.R. China.
| | - Biao Yan
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China.
| | - Jiayi Zhang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, P. R. China.
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5
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Seo H, Chung WG, Kwon YW, Kim S, Hong YM, Park W, Kim E, Lee J, Lee S, Kim M, Lim K, Jeong I, Song H, Park JU. Smart Contact Lenses as Wearable Ophthalmic Devices for Disease Monitoring and Health Management. Chem Rev 2023; 123:11488-11558. [PMID: 37748126 PMCID: PMC10571045 DOI: 10.1021/acs.chemrev.3c00290] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Indexed: 09/27/2023]
Abstract
The eye contains a complex network of physiological information and biomarkers for monitoring disease and managing health, and ocular devices can be used to effectively perform point-of-care diagnosis and disease management. This comprehensive review describes the target biomarkers and various diseases, including ophthalmic diseases, metabolic diseases, and neurological diseases, based on the physiological and anatomical background of the eye. This review also includes the recent technologies utilized in eye-wearable medical devices and the latest trends in wearable ophthalmic devices, specifically smart contact lenses for the purpose of disease management. After introducing other ocular devices such as the retinal prosthesis, we further discuss the current challenges and potential possibilities of smart contact lenses.
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Affiliation(s)
- Hunkyu Seo
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Won Gi Chung
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Yong Won Kwon
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Sumin Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Yeon-Mi Hong
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Wonjung Park
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Enji Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Jakyoung Lee
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Sanghoon Lee
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Moohyun Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Kyeonghee Lim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Inhea Jeong
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Hayoung Song
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Jang-Ung Park
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
- Department
of Neurosurgery, Yonsei University College
of Medicine, Seoul 03722, Republic of Korea
- Center
for Nanomedicine, Institute for Basic Science (IBS), Yonsei University, Seoul 03722, Republic
of Korea
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6
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Wang J, Azimi H, Zhao Y, Kaeser M, Vaca Sánchez P, Vazquez-Guardado A, Rogers JA, Harvey M, Rainer G. Optogenetic activation of visual thalamus generates artificial visual percepts. eLife 2023; 12:e90431. [PMID: 37791662 PMCID: PMC10593406 DOI: 10.7554/elife.90431] [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: 06/23/2023] [Accepted: 10/03/2023] [Indexed: 10/05/2023] Open
Abstract
The lateral geniculate nucleus (LGN), a retinotopic relay center where visual inputs from the retina are processed and relayed to the visual cortex, has been proposed as a potential target for artificial vision. At present, it is unknown whether optogenetic LGN stimulation is sufficient to elicit behaviorally relevant percepts, and the properties of LGN neural responses relevant for artificial vision have not been thoroughly characterized. Here, we demonstrate that tree shrews pretrained on a visual detection task can detect optogenetic LGN activation using an AAV2-CamKIIα-ChR2 construct and readily generalize from visual to optogenetic detection. Simultaneous recordings of LGN spiking activity and primary visual cortex (V1) local field potentials (LFPs) during optogenetic LGN stimulation show that LGN neurons reliably follow optogenetic stimulation at frequencies up to 60 Hz and uncovered a striking phase locking between the V1 LFP and the evoked spiking activity in LGN. These phase relationships were maintained over a broad range of LGN stimulation frequencies, up to 80 Hz, with spike field coherence values favoring higher frequencies, indicating the ability to relay temporally precise information to V1 using light activation of the LGN. Finally, V1 LFP responses showed sensitivity values to LGN optogenetic activation that were similar to the animal's behavioral performance. Taken together, our findings confirm the LGN as a potential target for visual prosthetics in a highly visual mammal closely related to primates.
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Affiliation(s)
- Jing Wang
- Department of Medicine, University of FribourgFribourgSwitzerland
- Department of Neurobiology, School of Basic Medical Sciences, Nanjing Medical UniversityNanjingChina
| | - Hamid Azimi
- Department of Medicine, University of FribourgFribourgSwitzerland
| | - Yilei Zhao
- Department of Medicine, University of FribourgFribourgSwitzerland
| | - Melanie Kaeser
- Department of Medicine, University of FribourgFribourgSwitzerland
| | | | | | - John A Rogers
- Querrey Simpson Institute for Bioelectronics, Northwestern UniversityEvanstonUnited States
| | - Michael Harvey
- Department of Medicine, University of FribourgFribourgSwitzerland
| | - Gregor Rainer
- Department of Medicine, University of FribourgFribourgSwitzerland
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Park J, Lee S, Lee M, Kim HS, Lee JY. Injectable Conductive Hydrogels with Tunable Degradability as Novel Implantable Bioelectrodes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300250. [PMID: 36828790 DOI: 10.1002/smll.202300250] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Indexed: 05/25/2023]
Abstract
Bioelectrodes have been developed to efficiently mediate electrical signals of biological systems as stimulators and recording devices. Recently, conductive hydrogels have garnered great attention as emerging materials for bioelectrode applications because they can permit intimate/conformal contact with living tissues and tissue-like softness. However, administration and control over the in vivo lifetime of bioelectrodes remain challenges. Here, injectable conductive hydrogels (ICHs) with tunable degradability as implantable bioelectrodes are developed. ICHs were constructed via thiol-ene reactions using poly(ethylene glycol)-tetrathiol and thiol-functionalized reduced graphene oxide with either hydrolyzable poly(ethylene glycol)-diacrylate or stable poly(ethylene glycol)-dimaleimide, the resultant hydrogels of which are degradable and nondegradable, respectively. The ICH electrodes had conductivities of 21-22 mS cm-1 and Young's moduli of 15-17 kPa, and showed excellent cell and tissue compatibility. The hydrolyzable conductive hydrogels disappeared 3 days after in vivo administration, while the stable conductive hydrogels maintained their shapes for up to 7 days. Our proof-of-concept studies reveal that electromyography signals with significantly improved sensitivity from rats could be obtained from the injected ICH electrodes compared to skin electrodes and injected nonconductive hydrogel electrodes. The ICHs, offering convenience in use, controllable degradation and excellent signal transmission, will have great potential to develop various bioelectronics devices.
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Affiliation(s)
- Junggeon Park
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Sanghun Lee
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Mingyu Lee
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Hyung-Seok Kim
- Department of Forensic Medicine, Chonnam National University Medical School, Gwangju, 61469, Republic of Korea
| | - Jae Young Lee
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
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8
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Duch Hurtado M, Vidal Oliver L, Marín Lambies C, Salom Alonso D. Microvascular quantitative metrics in retinitis pigmentosa using optical coherence tomography angiography. ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2023; 98:270-275. [PMID: 37031736 DOI: 10.1016/j.oftale.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 02/12/2023] [Indexed: 04/11/2023]
Abstract
AIMS To describe the changes in vessel density (VD) using optical coherence tomography angiography (OCTA) of the different sectors in the macular area between retinitis pigmentosa (RP) patients and controls. METHODS Observational case-control study. We initially included 22 patients with RP and 21 controls. We obtained 6 × 6 OCTA images of the macular area using Angio-OCT SS-DRI-Triton 1.22 (Topcon, Japan), together with visual acuity, biomicroscopy, visual field and optical coherence tomography examination. We compared the VD values in both groups for both superficial (SVP) and deep vascular plexus (DVP). Correlation between VD and macular thickness was also calculated. RESULTS The mean visual field index (VFI) in the RP group was 26.11% (+/- 17.29). VD was significantly lower in the RP group compared with healthy controls in all sectors of the DVP (Superior 43.48+/-3.79 vs 48.86+/-2.62, p < 0.0001; Nasal 40,52+/- 4.30 vs 46,01+/- 3.23, p = 0.0002; Inferior 42.76+/-5.26 vs 50.10+/- 3.36, p < 0.0001; Temporal 40.42+/- 4.46 vs 46.09+/-2.91, p = 0.0001) and in all but nasal sector in the SVP (Superior 39.86+/-4.46 vs 46.47+/- 2.61, p < 0.0001; Nasal 40.35+/- 4.56 vs 44.09+/-2.87, p = 0.0067; Inferior 40.74+/- 4.61 vs 46.58+/-3.26, p = 0.0002; Temporal 39.98+/-5.07 vs 44.78+/-3.28, p = 0.0024). Correlation between VD and macular thickness was positive and significant (RP: r = 0.59, p = 0.043; controls r = 0.51, p = 0.018). CONCLUSIONS Patients with advanced forms of RP have less vessel density in the macular area than healthy subjects. These differences are present in all four quadrants in the DVP and three in the SVP.
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Affiliation(s)
- M Duch Hurtado
- Servicio de Atención Primaria, Centro de Salud Pego, Alicante, Spain
| | - L Vidal Oliver
- Servicio de Oftalmología, Hospital Clínico Universitario Valencia, Valencia, Spain.
| | - C Marín Lambies
- Servicio de Oftalmología, Hospital de Manises, Manises, Valencia, Spain
| | - D Salom Alonso
- Servicio de Oftalmología, Hospital de Manises, Manises, Valencia, Spain
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Kavitha R. Analysis of Impact of Bioimpedance on Performance of Implant coil of Artificial Retina for Optimizing Q factor & Bandwidth. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2022; PP:142-151. [PMID: 37015408 DOI: 10.1109/tbcas.2022.3229669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Spiral coils are indispensable part of implantable electronics for facilitating wireless power and data transfer. Although many advanced high Q receiver design have emerged, implementing and retaining high Q in biological medium so as to improve link efficiency is challenging. This article bridges the gap between advanced techniques towards improving link efficiency and the tissue losses that deteriorates the Q factor of coil in heterogeneous tissue medium. The purpose of this research is to improve the Q factor and bandwidth of the coil in tissue medium by reducing the net conductance of the coil in tissue medium, which is comparable to the net conductance in air. Bioimpedance of each layer of the eye is modelled to identify the highly capacitive and highly conductive tissue layer in the eye. To investigate the worst-case and best-case scenario, Q factor and bandwidth of the implant coil is analysed in the eye with and without aqueous humor which is a highly conductive and capacitive tissue layer in the eye. The coil is encapsulated with breast fat which possess lowest permittivity of all body tissue. After removing the high conductive tissue layer from the implantation zone, the Q factor and bandwidth of the coil is improved by 87.5 % and 97.7 % respectively. It is observed that 100 % Q at 10 MHz and 76.75 % of bandwidth is recovered in tissue medium after using breast fat as encapsulation layer. This demonstration of coil for various test cases in tissue medium aids to device a reliable, safe and efficient wireless power/data transfer system for artificial retina.
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10
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Jeong H, Kim J, Seo JM, Neviani A. Neurostimulators for high-resolution artificial retina: ASIC design challenges and solutions. J Neural Eng 2022; 19. [PMID: 36374010 DOI: 10.1088/1741-2552/aca262] [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: 06/28/2022] [Accepted: 11/14/2022] [Indexed: 11/16/2022]
Abstract
Objective.Neurostimulator is one of the most important part in artificial retina design. In this paper, we discuss the main challenges in the design of application-specific integrated circuit for high-resolution artificial retina and suggest corresponding solutions.Approach. Problems in the design of the neurostimulator for the existing artificial retina have not been solved yet are analyzed and solutions are presented. For verification of the solutions, mathematical proof, MATLAB and Ansys simulations are used.Main results. The drawbacks of resorting to a high-voltage complementary metal oxide semiconductor (CMOS) process to deal with the large voltage compliance demanded by the stimulator output stage are pointed out, and an alternative approach based on a circuit that switches the voltage of the common reference electrode is proposed to overcome. The necessity of an active discharge circuit to remove the residual charge of electrodes caused by an unbalanced stimulus is investigated. We present a circuit analysis showing that the use of a passive discharge circuit is sufficient to suppress problematic direct current in most situations. Finally, possible restrictions on input and output (I/O) count are investigated by estimating the resistive-capacitive delay caused by the interconnection between the I/O pad and the microelectrode array.Significance. The results of this paper clarified the problems currently faced by neurostimulator design for the artificial retina. Through the solutions presented in this study, circuits with more competitiveness in power and area consumption can be designed.
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Affiliation(s)
- Hyunbeen Jeong
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
| | - Jisung Kim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
| | - Jong-Mo Seo
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea.,Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Andrea Neviani
- Department of Information Engineering, University of Padova, Padova, Italy
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11
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Erofeev A, Antifeev I, Bolshakova A, Bezprozvanny I, Vlasova O. In Vivo Penetrating Microelectrodes for Brain Electrophysiology. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22239085. [PMID: 36501805 PMCID: PMC9735502 DOI: 10.3390/s22239085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/14/2022] [Accepted: 11/22/2022] [Indexed: 05/13/2023]
Abstract
In recent decades, microelectrodes have been widely used in neuroscience to understand the mechanisms behind brain functions, as well as the relationship between neural activity and behavior, perception and cognition. However, the recording of neuronal activity over a long period of time is limited for various reasons. In this review, we briefly consider the types of penetrating chronic microelectrodes, as well as the conductive and insulating materials for microelectrode manufacturing. Additionally, we consider the effects of penetrating microelectrode implantation on brain tissue. In conclusion, we review recent advances in the field of in vivo microelectrodes.
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Affiliation(s)
- Alexander Erofeev
- Laboratory of Molecular Neurodegeneration, Graduate School of Biomedical Systems and Technologies, Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 Saint Petersburg, Russia
- Correspondence: (A.E.); (O.V.)
| | - Ivan Antifeev
- Laboratory of Methods and Instruments for Genetic and Immunoassay Analysis, Institute for Analytical Instrumentation of the Russian Academy of Sciences, 198095 Saint Petersburg, Russia
| | - Anastasia Bolshakova
- Laboratory of Molecular Neurodegeneration, Graduate School of Biomedical Systems and Technologies, Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 Saint Petersburg, Russia
| | - Ilya Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Graduate School of Biomedical Systems and Technologies, Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 Saint Petersburg, Russia
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Olga Vlasova
- Laboratory of Molecular Neurodegeneration, Graduate School of Biomedical Systems and Technologies, Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 Saint Petersburg, Russia
- Correspondence: (A.E.); (O.V.)
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12
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Rotov AY, Firsov ML. Optogenetic Prosthetization of Retinal Bipolar Cells. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022060011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
Although the experience of optogenetic retinal prosthetics
in animal models dates back to more than 16 years, the first results
obtained on humans have only been reported in the last year. Over this
period, the main challenges of prosthetics became clear and the
approaches to their solution were proposed. In this review, we aim
to present the achievements in the field of optogenetic prosthetization
of retinal bipolar cells with a focus mainly on relatively recent
publications. The review addresses the advantages and disadvantages
of bipolar cell prosthetics as compared to the alternative target,
retinal ganglion cells, and provides a comparative analysis of the
effectiveness of ionotropic light-sensitive proteins (channelrhodopsins)
or metabotropic receptors (rhodopsins) as prosthetic tools.
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13
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De Silva SR, Moore AT. Optogenetic approaches to therapy for inherited retinal degenerations. J Physiol 2022; 600:4623-4632. [PMID: 35908243 DOI: 10.1113/jp282076] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/18/2022] [Indexed: 01/07/2023] Open
Abstract
Inherited retinal degenerations such as retinitis pigmentosa (RP) affect around one in 4000 people and are the leading cause of blindness in working age adults in several countries. In these typically monogenic conditions, there is progressive degeneration of photoreceptors; however, inner retinal neurons such as bipolar cells and ganglion cells remain largely structurally intact, even in end-stage disease. Therapeutic approaches aiming to stimulate these residual cells, independent of the underlying genetic cause, could potentially restore visual function in patients with advanced vision loss, and benefit many more patients than therapies directed at the specific gene implicated in each disorder. One approach investigated for this purpose is that of optogenetics, a method of neuromodulation that utilises light to activate neurons engineered to ectopically express a light-sensitive protein. Using gene therapy via adeno-associated viral vectors, a range of photosensitive proteins have been expressed in remaining retinal cells in advanced retinal degeneration with in vivo studies demonstrating restoration of visual function. Developing an effective optogenetic strategy requires consideration of multiple factors, including the light-sensitive protein that is used, the vector and method for gene delivery, and the target cell for expression because these in turn may affect the quality of vision that can be restored. Currently, at least four clinical trials are ongoing to investigate optogenetic therapies in patients, with the ultimate aim of reversing visual loss in end-stage disease.
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Affiliation(s)
- Samantha R De Silva
- Oxford Eye Hospital, Oxford, UK.,UCL Institute of Ophthalmology, London, UK.,Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, London, UK.,Ophthalmology Department, University of California, San Francisco, CA, USA
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14
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Caravaca-Rodriguez D, Gaytan SP, Suaning GJ, Barriga-Rivera A. Implications of Neural Plasticity in Retinal Prosthesis. Invest Ophthalmol Vis Sci 2022; 63:11. [PMID: 36251317 DOI: 10.1167/iovs.63.11.11] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Retinal degenerative diseases such as retinitis pigmentosa cause a progressive loss of photoreceptors that eventually prevents the affected person from perceiving visual sensations. The absence of a visual input produces a neural rewiring cascade that propagates along the visual system. This remodeling occurs first within the retina. Then, subsequent neuroplastic changes take place at higher visual centers in the brain, produced by either the abnormal neural encoding of the visual inputs delivered by the diseased retina or as the result of an adaptation to visual deprivation. While retinal implants can activate the surviving retinal neurons by delivering electric current, the unselective activation patterns of the different neural populations that exist in the retinal layers differ substantially from those in physiologic vision. Therefore, artificially induced neural patterns are being delivered to a brain that has already undergone important neural reconnections. Whether or not the modulation of this neural rewiring can improve the performance for retinal prostheses remains a critical question whose answer may be the enabler of improved functional artificial vision and more personalized neurorehabilitation strategies.
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Affiliation(s)
- Daniel Caravaca-Rodriguez
- Department of Applied Physics III, Technical School of Engineering, Universidad de Sevilla, Sevilla, Spain
| | - Susana P Gaytan
- Department of Physiology, Universidad de Sevilla, Sevilla, Spain
| | - Gregg J Suaning
- School of Biomedical Engineering, University of Sydney, Sydney, Australia
| | - Alejandro Barriga-Rivera
- Department of Applied Physics III, Technical School of Engineering, Universidad de Sevilla, Sevilla, Spain.,School of Biomedical Engineering, University of Sydney, Sydney, Australia
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15
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Rubner R, Li KV, Canto-Soler MV. Progress of clinical therapies for dry age-related macular degeneration. Int J Ophthalmol 2022; 15:157-166. [PMID: 35047371 DOI: 10.18240/ijo.2022.01.23] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 10/08/2021] [Indexed: 01/10/2023] Open
Abstract
Dry age-related macular degeneration (AMD) is a progressive blinding disease that currently affects millions of people worldwide with no successful treatment available. Significant research efforts are currently underway to develop therapies aimed at slowing the progression of this disease or, more notably, reversing it. Here the therapies which have reached clinical trial for treatment of dry AMD were reviewed. A thorough search of PubMed, Embase, and Clinicaltrials.gov has led to a comprehensive collection of the most recent strategies being evaluated. This review also endeavors to assess the status and future directions of therapeutics for this debilitating condition.
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Affiliation(s)
- Rhianna Rubner
- CellSight Ocular Stem Cell and Regeneration Research Program, Department of Ophthalmology, Sue Anschutz-Rodgers Eye Center, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kang V Li
- CellSight Ocular Stem Cell and Regeneration Research Program, Department of Ophthalmology, Sue Anschutz-Rodgers Eye Center, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - M Valeria Canto-Soler
- CellSight Ocular Stem Cell and Regeneration Research Program, Department of Ophthalmology, Sue Anschutz-Rodgers Eye Center, University of Colorado School of Medicine, Aurora, CO 80045, USA
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16
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Otte E, Vlachos A, Asplund M. Engineering strategies towards overcoming bleeding and glial scar formation around neural probes. Cell Tissue Res 2022; 387:461-477. [PMID: 35029757 PMCID: PMC8975777 DOI: 10.1007/s00441-021-03567-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/17/2021] [Indexed: 12/15/2022]
Abstract
Neural probes are sophisticated electrophysiological tools used for intra-cortical recording and stimulation. These microelectrode arrays, designed to penetrate and interface the brain from within, contribute at the forefront of basic and clinical neuroscience. However, one of the challenges and currently most significant limitations is their ‘seamless’ long-term integration into the surrounding brain tissue. Following implantation, which is typically accompanied by bleeding, the tissue responds with a scarring process, resulting in a gliotic region closest to the probe. This glial scarring is often associated with neuroinflammation, neurodegeneration, and a leaky blood–brain interface (BBI). The engineering progress on minimizing this reaction in the form of improved materials, microfabrication, and surgical techniques is summarized in this review. As research over the past decade has progressed towards a more detailed understanding of the nature of this biological response, it is time to pose the question: Are penetrating probes completely free from glial scarring at all possible?
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17
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Esquenazi RB, Meier K, Beyeler M, Boynton GM, Fine I. Learning to see again: Perceptual learning of simulated abnormal on- off-cell population responses in sighted individuals. J Vis 2021; 21:10. [PMID: 34935878 PMCID: PMC8727313 DOI: 10.1167/jov.21.13.10] [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
Many forms of artificial sight recovery, such as electronic implants and optogenetic proteins, generally cause simultaneous, rather than complementary firing of on- and off-center retinal cells. Here, using virtual patients—sighted individuals viewing distorted input—we examine whether plasticity might compensate for abnormal neuronal population responses. Five participants were dichoptically presented with a combination of original and contrast-reversed images. Each image (I) and its contrast-reverse (Iʹ) was filtered using a radial checkerboard (F) in Fourier space and its inverse (Fʹ). [I * F′] + [Iʹ * F] was presented to one eye, and [I * F] + [Iʹ * F′] was presented to the other, such that regions of the image that produced on-center responses in one eye produced off-center responses in the other eye, and vice versa. Participants continuously improved in a naturalistic object discrimination task over 20 one-hour sessions. Pre-training and post-training tests suggest that performance improvements were due to two learning processes: learning to recognize objects with reduced visual information and learning to suppress contrast-reversed image information in a non–eye-selective manner. These results suggest that, with training, it may be possible to adapt to the unnatural on- and off-cell population responses produced by electronic and optogenetic sight recovery technologies.
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Affiliation(s)
| | - Kimberly Meier
- Department of Psychology, University of Washington, USA.,
| | - Michael Beyeler
- Department of Computer Science, University of California, Santa Barbara, Santa Barbara, California, USA.,Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, California, USA.,
| | | | - Ione Fine
- Department of Psychology, University of Washington, USA.,
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18
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Colombo L, Maltese PE, Romano D, Fogagnolo P, Castori M, Marceddu G, Cristofoli F, Percio M, Piteková B, Modarelli AM, Bertelli M, Rossetti L. SD-OCT analysis in syndromic and non-syndromic forms of retinitis pigmentosa due to USH2A gene mutations. Ophthalmic Res 2021; 65:180-195. [PMID: 34781295 DOI: 10.1159/000520329] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 10/09/2021] [Indexed: 11/19/2022]
Abstract
INTRODUCTION This study aims to analyze macular structure by using SD-OCT in a cohort of patients affected by autosomal recessive retinitis pigmentosa and Usher syndrome, due to genetic variants in USH2A gene, and to correlate OCT parameters with functional and genetic data. METHODS The subjects of this study were 92 patients, 46 syndromic (Ush2) and 46 non-syndromic (arRP), with clinical and genetic diagnosis of USH2A-related retinal dystrophy, who underwent a complete ophthalmic examination and spectral domain OCT analysis. The study focused on evaluating the differences between the two groups in the following parameters: best corrected visual acuity (BCVA), ellipsoid zone width (EZ), presence of epiretinal membrane (ERM) and cystic macular lesions (CML). Variants in USH2A gene were divided in 3 categories, according to the expected impact (low/high) at protein level of the different variants on each allele. RESULTS BCVA and EZ width were significantly lower in Ush2 than in arRP patients (p < 0.0001 and p = 0.001). ERM was detected in 34.8% (16/46) of arRP patients and in 65.2% (30/46) of Ush2 patients (p = 0.003). CML was detected in 17.4% (8/46) of arRP patients and 30.4% (14/46) of Ush2 patients (p = 0.14). The allelic distribution was statistically different (p = 0.0003) by dividing the two diseases: for Ush2 patients it was 45.7% (high/high), 39.1% (low/high) and 15.2% (low/low); for arRP patients it was 8.7% (high/high), 56.5% (low/high) and 34.8% (low/low). The severity class of the variants significantly affected VA and EZ width parameters (p = 0.004 and p = 0.002, respectively). CONCLUSION Retinal disease, as evaluated by means of SD-OCT, shows more advanced degeneration signs in the syndromic than the non-syndromic form of retinal dystrophy related to USH2A gene. Variant types and allelic profiles are determining factors for the onset of syndromic features. However, since the three allelic profiles can be found in both Usher and RP patients, other factors must necessarily play a determining role.
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Affiliation(s)
- Leonardo Colombo
- Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, Milan, Italy
| | | | - Dario Romano
- Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, Milan, Italy
| | - Paolo Fogagnolo
- Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, Milan, Italy
| | - Marco Castori
- Division of Medical Genetics, Fondazione IRCCS-Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | | | | | | | - Barbora Piteková
- Department of Pediatrics, Comenius University Faculty of Medicine, National Institute of Children's Diseases, Bratislava, Slovakia
| | - Antonio Mattia Modarelli
- Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, Milan, Italy
| | - Matteo Bertelli
- MAGI'S Lab s.r.l., Rovereto, Italy
- MAGI Euregio s.c.s., Bolzano, Italy
| | - Luca Rossetti
- Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, Milan, Italy
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19
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Too LK, Simunovic MP. Retinal Stem/Progenitor Cells Derived From Adult Müller Glia for the Treatment of Retinal Degeneration. Front Cell Dev Biol 2021; 9:749131. [PMID: 34660607 PMCID: PMC8511496 DOI: 10.3389/fcell.2021.749131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/06/2021] [Indexed: 01/09/2023] Open
Abstract
Over the past two decades, progress in our understanding of glial function has been revolutionary. Within the retina, a subset of glial cells termed the “Müller glia (MG),” have been demonstrated to play key roles in retinal homeostasis, structure and metabolism. Additionally, MG have also been shown to possess the regenerative capacity that varies across species. In teleost fish, MG respond to injury by reprogramming into stem-like cells capable of regenerating lost tissue. The expression of stem/progenitor cell markers has been demonstrated broadly in mammalian MG, including human MG, but their in vivo regenerative capacity appears evolutionarily limited. Advances in stem cell therapy have progressively elucidated critical mechanisms underlying innate MG reprogramming in teleost fish, which have shown promising results when applied to rodents. Furthermore, when cultured ex vivo, MG from mammals can differentiate into several retina cell types. In this review, we will explore the reparative and regenerative potential of MG in cellular therapy approaches, and outline our current understanding of embryonic retinal development, the stem-cell potential of MG in adult vertebrate retina (including human), and microenvironmental cues that guide MG reprogramming.
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Affiliation(s)
- Lay Khoon Too
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Matthew P Simunovic
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,Sydney Eye Hospital, Sydney, NSW, Australia
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20
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Hossaini A, Valeriani D, Nam CS, Ferrante R, Mahmud M. A Functional BCI Model by the P2731 working group: Physiology. BRAIN-COMPUTER INTERFACES 2021. [DOI: 10.1080/2326263x.2021.1968665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Ali Hossaini
- Department of Engineering, King’s College London, London, UK
| | | | - Chang S. Nam
- Department of Industrial and Systems Engineering, North Carolina State University, Raleigh, NC, USA
| | | | - Mufti Mahmud
- School of Science and Technology, Nottingham Trent University, Nottingham, UK
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21
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Turner BL, Senevirathne S, Kilgour K, McArt D, Biggs M, Menegatti S, Daniele MA. Ultrasound-Powered Implants: A Critical Review of Piezoelectric Material Selection and Applications. Adv Healthc Mater 2021; 10:e2100986. [PMID: 34235886 DOI: 10.1002/adhm.202100986] [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: 05/20/2021] [Revised: 06/15/2021] [Indexed: 12/14/2022]
Abstract
Ultrasound-powered implants (UPIs) represent cutting edge power sources for implantable medical devices (IMDs), as their powering strategy allows for extended functional lifetime, decreased size, increased implant depth, and improved biocompatibility. IMDs are limited by their reliance on batteries. While batteries proved a stable power supply, batteries feature relatively large sizes, limited life spans, and toxic material compositions. Accordingly, energy harvesting and wireless power transfer (WPT) strategies are attracting increasing attention by researchers as alternative reliable power sources. Piezoelectric energy scavenging has shown promise for low power applications. However, energy scavenging devices need be located near sources of movement, and the power stream may suffer from occasional interruptions. WPT overcomes such challenges by more stable, on-demand power to IMDs. Among the various forms of WPT, ultrasound powering offers distinct advantages such as low tissue-mediated attenuation, a higher approved safe dose (720 mW cm-2 ), and improved efficiency at smaller device sizes. This study presents and discusses the state-of-the-art in UPIs by reviewing piezoelectric materials and harvesting devices including lead-based inorganic, lead-free inorganic, and organic polymers. A comparative discussion is also presented of the functional material properties, architecture, and performance metrics, together with an overview of the applications where UPIs are being deployed.
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Affiliation(s)
- Brendan L. Turner
- Joint Department of Biomedical Engineering North Carolina State University and University of North Carolina Chapel Hill, 911 Oval Dr. Raleigh NC 27695 USA
| | - Seedevi Senevirathne
- The Patrick G Johnston Centre for Cancer Research Queen's University 97 Lisburn Rd Belfast BT9 7AE UK
| | - Katie Kilgour
- Department of Chemical and Biomolecular Engineering North Carolina State University Raleigh NC 27695 USA
| | - Darragh McArt
- The Patrick G Johnston Centre for Cancer Research Queen's University 97 Lisburn Rd Belfast BT9 7AE UK
| | - Manus Biggs
- Centre for Research in Medical Devices National University of Ireland Newcastle Road Galway H91 W2TY Ireland
| | - Stefano Menegatti
- Department of Chemical and Biomolecular Engineering North Carolina State University Raleigh NC 27695 USA
| | - Michael A. Daniele
- Joint Department of Biomedical Engineering North Carolina State University and University of North Carolina Chapel Hill, 911 Oval Dr. Raleigh NC 27695 USA
- Department of Electrical and Computer Engineering North Carolina State University 890 Oval Dr. Raleigh NC 27695 USA
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22
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Tholl M, Spring M, de Brot S, Casoni D, Zurbuchen A, Tanner H, Haeberlin A. Implications of wound healing on subcutaneous photovoltaic energy harvesting. IEEE Trans Biomed Eng 2021; 69:23-31. [PMID: 34086560 DOI: 10.1109/tbme.2021.3086671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Implanted cardiac pacemakers must be regularly replaced due to depleted batteries. A possible alternative is proposed by subcutaneous photovoltaic energy harvesting. The bodys reaction to an implant can cause device encapsulation. Potential changes in spectral light transmission of skin can inuence the performance of subcutaneous photovoltaic cells and has not yet been studied in large animal studies. METHODS Subcutaneous implants measuring changes in the light reaching the implant were developed. Three pigs received those implants and were analyzed for seven weeks. Spectral measurements with known irradiation were performed to identify possible changes in the transparency of the tissues above the implant during the wound healing process. A histological analysis at the end of the trial investigated the skin tissue above the subcutaneous photovoltaic implants. RESULTS The implants measured decreasing light intensity and shifts in the lights spectrum during the initial wound healing phase. In a later stage of tissue recovery, the implants measured a generally reduced light intensity compared to the healthy tissue after implantation. The spectral distribution of the measured light at the end of the trial was similar to the rst measurements. The histological analysis showed subcutaneous granulation tissue formation for all devices. CONCLUSION The varying reduction of light intensity reaching the implants means that safety margins must be sufciently high to ensure the power. At the end of the wound healing process, the spectral distribution of the light reaching the implant is similar to healthy tissue. Signicance: Optimizations of spectral sensitivity of photovoltaic cells are possible.
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23
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Kare SS, Rountree CM, Troy JB, Finan JD, Saggere L. Neuromodulation using electroosmosis. J Neural Eng 2021; 18:10.1088/1741-2552/ac00d3. [PMID: 33984848 PMCID: PMC8177066 DOI: 10.1088/1741-2552/ac00d3] [Citation(s) in RCA: 1] [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: 08/20/2020] [Accepted: 05/13/2021] [Indexed: 11/12/2022]
Abstract
Objective.Our laboratory has proposed chemical stimulation of retinal neurons using exogenous glutamate as a biomimetic strategy for treating vision loss caused by photoreceptor (PR) degenerative diseases. Although our previousin-vitrostudies using pneumatic actuation indicate that chemical retinal stimulation is achievable, an actuation technology that is amenable to microfabrication, as needed for anin-vivoimplantable device, has yet to be realized. In this study, we sought to evaluate electroosmotic flow (EOF) as a mechanism for delivering small quantities of glutamate to the retina. EOF has great potential for miniaturization.Approach.An EOF device to dispense small quantities of glutamate was constructed and its ability to drive retinal output tested in anin-vitropreparation of PR degenerate rat retina.Main results.We built and tested an EOF microfluidic system, with 3D printed and off-the-shelf components, capable of injecting small volumes of glutamate in a pulsatile fashion when a low voltage control signal was applied. With this device, we produced excitatory and inhibitory spike rate responses in PR degenerate rat retinae. Glutamate evoked spike rate responses were also observed to be voltage-dependent and localized to the site of injection.Significance.The EOF device performed similarly to a previously tested conventional pneumatic microinjector as a means of chemically stimulating the retina while eliminating the moving plunger of the pneumatic microinjector that would be difficult to miniaturize and parallelize. Although not implantable, the prototype device presented here as a proof of concept indicates that a retinal prosthetic based on EOF-driven chemical stimulation is a viable and worthwhile goal. EOF should have similar advantages for controlled dispensing of charged neurochemicals at any neural interface.
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Affiliation(s)
- Sai Siva Kare
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Corey M Rountree
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
| | - John B Troy
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
| | - John D Finan
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Laxman Saggere
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
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Mailhot N, Cheriton R, Vyas K, Cook J, Prawer S, Hinzer K, Spinello D. Eighty-Five Percent of Improved Optical Power Delivery to Epiretinal Prostheses Using Rigid Body Compensation Algorithm. J Biomech Eng 2021; 143:061009. [PMID: 33537711 DOI: 10.1115/1.4050026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Indexed: 11/08/2022]
Abstract
Vision impairment caused by degenerative retinal pathologies such as age-related macular degeneration can be treated using retinal implants. Such devices receive power and data using cables passing through a permanent surgical incision in the eye wall (sclera), which increases the risk to patients and surgical costs. A recently developed retinal implant design eliminates the necessity of the implant cable using a photonic power converter (PPC), which receives optical power and data through the pupil and is directed by an ellipsoidal reflector and micro-electromechanical mirror. We present a misalignment compensation algorithm model that accounts for rigid-body motions of the reflector relative to the eye and applies the correction to the mirror coordinates in the presence of angular misalignment of the reflector. We demonstrate that up to 85% of the nominal optical power can be delivered to the implant with axial reflector misalignments up to 30 deg using the compensation algorithm.
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Affiliation(s)
- Nathaniel Mailhot
- Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - Ross Cheriton
- National Research Council of Canada, Ottawa, ON K1N 6M6, Canada
| | - Kaustubh Vyas
- Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - John Cook
- Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - Steven Prawer
- Department of Physics, University of Melbourne, Melbourne VIC 3010, Australia
| | - Karin Hinzer
- Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - Davide Spinello
- Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6M6, Canada
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Gaillet V, Borda E, Zollinger EG, Ghezzi D. A machine-learning algorithm correctly classifies cortical evoked potentials from both visual stimulation and electrical stimulation of the optic nerve. J Neural Eng 2021; 18. [PMID: 33823498 DOI: 10.1088/1741-2552/abf523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 04/06/2021] [Indexed: 11/12/2022]
Abstract
Objective. Optic nerve's intraneural stimulation is an emerging neuroprosthetic approach to provide artificial vision to totally blind patients. An open question is the possibility to evoke individual non-overlapping phosphenes via selective intraneural optic nerve stimulation. To begin answering this question, first, we aim at showing in preclinical experiments with animals that each intraneural electrode could evoke a distinguishable activity pattern in the primary visual cortex.Approach. We performed both patterned visual stimulation and patterned electrical stimulation in healthy rabbits while recording evoked cortical activity with an electrocorticogram array in the primary visual cortex. Electrical stimulation was delivered to the optic nerve with the intraneural array OpticSELINE. We used a support vector machine algorithm paired to a linear regression model to classify cortical responses originating from visual stimuli located in different portions of the visual field and electrical stimuli from the different electrodes of the OpticSELINE.Main results. Cortical activity induced by visual and electrical stimulation could be classified with nearly 100% accuracy relative to the specific location in the visual field or electrode in the array from which it originated. For visual stimulation, the accuracy increased with the separation of the stimuli and reached 100% for separation higher than 7°. For electrical stimulation, at low current amplitudes, the accuracy increased with the distance between electrodes, while at higher current amplitudes, the accuracy was nearly 100% already for the shortest separation.Significance. Optic nerve's intraneural stimulation with the OpticSELINE induced discernible cortical activity patterns. These results represent a necessary condition for an optic nerve prosthesis to deliver vision with non-overlapping phosphene. However, clinical investigations will be required to assess the translation of these results into perceptual phenomena.
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Affiliation(s)
- Vivien Gaillet
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
| | - Eleonora Borda
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
| | - Elodie Geneviève Zollinger
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
| | - Diego Ghezzi
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
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Michalakis S, Gerhardt M, Rudolph G, Priglinger S, Priglinger C. Gene Therapy for Inherited Retinal Disorders: Update on Clinical Trials. Klin Monbl Augenheilkd 2021; 238:272-281. [PMID: 33784790 DOI: 10.1055/a-1384-0818] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Within the last decade, continuous advances in molecular biological techniques have made it possible to develop causative therapies for inherited retinal disorders (IRDs). Some of the most promising options are gene-specific approaches using adeno-associated virus-based vectors to express a healthy copy of the disease-causing gene in affected cells of a patient. This concept of gene supplementation therapy is already advocated for the treatment of retinal dystrophy in RPE65-linked Leber's congenital amaurosis (LCA) patients. While the concept of gene supplementation therapy can be applied to treat autosomal recessive and X-linked forms of IRD, it is not sufficient for autosomal dominant IRDs, where the pathogenic gene product needs to be removed. Therefore, for autosomal dominant IRDs, alternative approaches that utilize CRISPR/Cas9 or antisense oligonucleotides to edit or deplete the mutant allele or gene product are needed. In recent years, research retinal gene therapy has intensified and promising approaches for various forms of IRD are currently in preclinical and clinical development. This review article provides an overview of current clinical trials for the treatment of IRDs.
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Affiliation(s)
| | - Maximilian Gerhardt
- Department of Ophthalmology, University Hospital, LMU Munich, München, Germany
| | - Günter Rudolph
- Department of Ophthalmology, University Hospital, LMU Munich, München, Germany
| | | | - Claudia Priglinger
- Department of Ophthalmology, University Hospital, LMU Munich, München, Germany
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Simultaneous Power Feedback and Maximum Efficiency Point Tracking for Miniaturized RF Wireless Power Transfer Systems. SENSORS 2021; 21:s21062023. [PMID: 33809337 PMCID: PMC8000423 DOI: 10.3390/s21062023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/05/2021] [Accepted: 03/09/2021] [Indexed: 11/17/2022]
Abstract
Near-field interfaces with miniaturized coil systems and low output power levels, such as applied in biomedical sensor systems, can suffer from severe efficiency degradation due to dynamic impedance mismatches, reducing battery life of the power transmitter unit and requiring to increase the level of electromagnetic emission. Moreover, the stability of weakly-coupled power transfer systems is generally limited by transient changes in coil alignment and load power consumption. Hence, a central research question in the domain of wireless power transfer is how to realize an adaptive impedance matching system under the constraints of a simultaneous power feedback to increase the system’s efficiency and stability, while maintaining circuit characteristics such as small size, low power consumption and fast reaction times. This paper presents a novel approach based on a two-stage control loop implemented in the primary-side reader unit, which uses a digital PI controller to maintain the rectifier output voltage for power feedback and an on-top perturb-and-observe controller configuring the setpoint of the voltage controller to maximize efficiency. The paper mathematically analyzes the AC and DC transfer characteristics of a resonant inductive link to design the reactive AC matching network, the digital voltage controller and ultimately the DC-domain impedance matching algorithm. It was found that static reactive L networks result in suitable efficiency levels for coils with sufficiently high quality factor even without adaptive tuning of operational frequency or reactive components. Furthermore, the regulated output voltage of the rectifier is a direct measure of the DC load impedance when using a regular DC/DC converter to supply the load circuits, so that this quantity can be tuned to maximize efficiency. A prototype implementation demonstrates the algorithms in a 40.68 MHz inductive link with load power levels from 10 to 100 mW and tuning time constants of 300 ms, while allowing for a simplified receiver with a footprint smaller than 200 mm2 and a self-consumption below 1 mW. Hence, the presented concepts enable adaptive impedance matching with favorable characteristics for low-energy sensor systems, i.e., minimized footprint, power level and reaction time.
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Tholl MV, Zurbuchen A, Tanner H, Haeberlin A. Potential of subdermal solar energy harvesting for medical device applications based on worldwide meteorological data. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-200334RR. [PMID: 33694336 PMCID: PMC7946961 DOI: 10.1117/1.jbo.26.3.038002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 02/12/2021] [Indexed: 06/12/2023]
Abstract
SIGNIFICANCE Active implants require batteries as power supply. Their lifetime is limited and may require a second surgical intervention for replacement. Intracorporal energy harvesting techniques generate power within the body and supply the implant. Solar cells below the skin can be used to harvest energy from light. AIM To investigate the potential of subdermal solar energy harvesting. APPROACH We evaluated global radiation data for defined time slots and calculated the output power of a subdermal solar module based on skin and solar cell characteristics. We assumed solar exposure profiles based on daily habits for an implanted solar cell. The output power was calculated for skin types VI and I/II. RESULTS We show that the yearly mean power in most locations on Earth is sufficient to power modern cardiac pacemakers if 10 min midday solar irradiation is assumed. All skin types are suitable for solar harvesting. Moreover, we provide a software tool to predict patient-specific output power. CONCLUSIONS Subdermal solar energy harvesting is a viable alternative to primary batteries. The comparison to a human case study showed a good agreement of the results. The developed code is available open source to enable researchers to investigate further applications of subdermal solar harvesting.
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Affiliation(s)
- Maximilien V. Tholl
- University of Bern, sitem Center for Translational Medicine and Biomedical Entrepreneurship, Bern, Switzerland
- Bern University Hospital, Department of Cardiology, Bern, Switzerland
| | - Adrian Zurbuchen
- University of Bern, sitem Center for Translational Medicine and Biomedical Entrepreneurship, Bern, Switzerland
| | - Hildegard Tanner
- Bern University Hospital, Department of Cardiology, Bern, Switzerland
| | - Andreas Haeberlin
- University of Bern, sitem Center for Translational Medicine and Biomedical Entrepreneurship, Bern, Switzerland
- Bern University Hospital, Department of Cardiology, Bern, Switzerland
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Chenais NAL, Airaghi Leccardi MJI, Ghezzi D. Naturalistic spatiotemporal modulation of epiretinal stimulation increases the response persistence of retinal ganglion cell. J Neural Eng 2021; 18. [DOI: 10.1088/1741-2552/abcd6f] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/24/2020] [Indexed: 12/24/2022]
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Abstract
Illusions and hallucinations are commonly encountered in both daily life and clinical practice. In this chapter, we review definitions and possible underlying mechanisms of these phenomena and then review what is known about specific conditions that are associated with them, including ophthalmic causes, migraine, epilepsy, Parkinson's disease, and schizophrenia. We then discuss specific syndromes including the Charles Bonnet syndrome, visual snow syndrome, Alice in Wonderland syndrome, and peduncular hallucinosis. The scientific study of illusions and hallucinations has contributed significantly to our understanding of how eye and brain process vision and contribute to perception. Important concepts are the distinction between topologic and hodologic mechanisms underlying hallucinations and the involvement of attentional networks. This chapter examines the various ways in which pathological illusions and hallucinations might arise in relation to the phenomenology and known pathology of the various conditions associated with them.
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Affiliation(s)
- Clare L Fraser
- Department of Ophthalmology, Save Sight Institute, Faculty of Health and Medicine, University of Sydney, Sydney, Australia.
| | - Christian J Lueck
- Department of Neurology, Canberra Hospital, and Australian National University Medical School, Canberra, Australia
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31
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Park JH, Tan JSY, Wu H, Dong Y, Yoo J. 1225-Channel Neuromorphic Retinal-Prosthesis SoC With Localized Temperature-Regulation. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2020; 14:1230-1240. [PMID: 33156793 DOI: 10.1109/tbcas.2020.3036091] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A 1225-Channel Neuromorphic Retinal Prosthesis (RP) SoC is presented. Existing RP SoCs directly convert light intensity to electrical stimulus, which limit the adoption of delicate stimulus patterns to increase visual acuity. Moreover, a conventional centralized image processor leads to the local hot spot that poses a risk to the nearby retinal cells. To solve these issues, the proposed SoC adopts a distributed Neuromorphic Image Processor (NMIP) located within each pixel that extracts the outline of the incoming image, which reduces current dispersion and stimulus power compared with light-intensity proportional stimulus pattern. A spike-based asynchronous digital operation results in the power consumption of 56.3 nW/Ch without local temperature hot spot. At every 5×5 pixels, the localized (49-point) temperature-regulation circuit limits the temperature increase of neighboring retinal cells to less than 1 °C, and the overall power consumption of the SoC to be less than that of the human eye. The 1225-channel SoC fabricated in 0.18 μm 1P6M CMOS occupies 15mm2 while consuming 2.7 mW, and is successfully verified with image reconstruction demonstration.
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Faber H, Besch D, Bartz‐Schmidt K, Eisenstein H, Roider J, Sachs H, Gekeler F, Zrenner E, Stingl K. Restriction of eye motility in patients with RETINA IMPLANT Alpha AMS. Acta Ophthalmol 2020; 98:e998-e1003. [PMID: 32304165 DOI: 10.1111/aos.14435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 03/16/2020] [Indexed: 12/22/2022]
Abstract
PURPOSE To evaluate the motility of the eye in patients with the RETINA IMPLANT Alpha AMS. METHODS Eye motility was determined in eight gaze directions in ten blind retinitis pigmentosa patients, who had received the RETINA IMPLANT Alpha AMS, before implantation of the subretinal implant and at six time-points up to one year after. RESULTS The analysis of eye motility showed a restriction in the upgaze and gaze to the temporal side directly after surgery in eight of the nine patients included. The degree of motility restriction decreased continuously with recovery during the observation time. One year after surgery, eye motility was still restricted in the majority of patients, especially in the upgaze to the temporal side at 20° (five of seven patients). CONCLUSION Retinal implants with intraorbital parts (e.g. connecting cables) caused restriction in the temporal and superior viewing directions in the majority of patients. Although this restriction might be cosmetically visible, this limitation in eye motility has no effects on the monocular vision and the implant's efficacy for daily use.
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Affiliation(s)
- Hanna Faber
- University Eye Hospital Center for Ophthalmology Eberhard Karls University Tuebingen Germany
| | - Dorothea Besch
- University Eye Hospital Center for Ophthalmology Eberhard Karls University Tuebingen Germany
| | | | - Hanna Eisenstein
- University Eye Hospital Center for Ophthalmology Eberhard Karls University Tuebingen Germany
| | - Johann Roider
- Department of Ophthalmology Christian‐Albrechts‐University of Kiel University Medical Center Kiel Germany
| | - Helmut Sachs
- Städtisches Klinikum Dresden Friedrichstadt Dresden Germany
| | - Florian Gekeler
- Department of Ophthalmology Klinikum Stuttgart Stuttgart Germany
| | - Eberhart Zrenner
- Institute for Ophthalmic Research Center for Ophthalmology Eberhard Karls University Tuebingen Germany
- Werner Reichardt Centre for Integrative Neuroscience Eberhard Karls University Tuebingen Tuebingen Germany
| | - Katarina Stingl
- University Eye Hospital Center for Ophthalmology Eberhard Karls University Tuebingen Germany
- Center for Rare Eye Diseases Eberhard Karls University Tuebingen Germany
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Rincón Montes V, Gehlen J, Ingebrandt S, Mokwa W, Walter P, Müller F, Offenhäusser A. Development and in vitro validation of flexible intraretinal probes. Sci Rep 2020; 10:19836. [PMID: 33199768 PMCID: PMC7669900 DOI: 10.1038/s41598-020-76582-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/28/2020] [Indexed: 12/01/2022] Open
Abstract
The efforts to improve the treatment efficacy in blind patients with retinal degenerative diseases would greatly benefit from retinal activity feedback, which is lacking in current retinal implants. While the door for a bidirectional communication device that stimulates and records intraretinally has been opened by the recent use of silicon-based penetrating probes, the biological impact induced by the insertion of such rigid devices is still unknown. Here, we developed for the first time, flexible intraretinal probes and validated in vitro the acute biological insertion impact in mouse retinae compared to standard silicon-based probes. Our results show that probes based on flexible materials, such as polyimide and parylene-C, in combination with a narrow shank design 50 µm wide and 7 µm thick, and the use of insertion speeds as high as 187.5 µm/s will successfully penetrate the retina, reduce the footprint of the insertion to roughly 2 times the cross-section of the probe, and induce low dead cell counts, while keeping the vitality of the tissue and recording the neural activity at different depths.
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Affiliation(s)
- V Rincón Montes
- Bioelectronics, Institute of Biological Information Processing-3, Forschungszentrum Jülich, Jülich, Germany
- RWTH Aachen University, Aachen, Germany
| | - J Gehlen
- Molecular and Cellular Physiology, Institute of Biological Information Processing-1, Forschungszentrum Jülich, Jülich, Germany
| | - S Ingebrandt
- Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Aachen, Germany
| | - W Mokwa
- Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Aachen, Germany
| | - P Walter
- Department of Ophthalmology, RWTH Aachen University, Aachen, Germany
| | - F Müller
- Molecular and Cellular Physiology, Institute of Biological Information Processing-1, Forschungszentrum Jülich, Jülich, Germany
| | - A Offenhäusser
- Bioelectronics, Institute of Biological Information Processing-3, Forschungszentrum Jülich, Jülich, Germany.
- RWTH Aachen University, Aachen, Germany.
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Thorn JT, Migliorini E, Ghezzi D. Virtual reality simulation of epiretinal stimulation highlights the relevance of the visual angle in prosthetic vision. J Neural Eng 2020; 17:056019. [DOI: 10.1088/1741-2552/abb5bc] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Baroncelli L, Lunghi C. Neuroplasticity of the visual cortex: in sickness and in health. Exp Neurol 2020; 335:113515. [PMID: 33132181 DOI: 10.1016/j.expneurol.2020.113515] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/14/2020] [Accepted: 10/21/2020] [Indexed: 01/18/2023]
Abstract
Brain plasticity refers to the ability of synaptic connections to adapt their function and structure in response to experience, including environmental changes, sensory deprivation and injuries. Plasticity is a distinctive, but not exclusive, property of the developing nervous system. This review introduces the concept of neuroplasticity and describes classic paradigms to illustrate cellular and molecular mechanisms underlying synapse modifiability. Then, we summarize a growing number of studies showing that the adult cerebral cortex retains a significant degree of plasticity highlighting how the identification of strategies to enhance the plastic potential of the adult brain could pave the way for the development of novel therapeutic approaches aimed at treating amblyopia and other neurodevelopmental disorders. Finally, we analyze how the visual system adjusts to neurodegenerative conditions leading to blindness and we discuss the crucial role of spared plasticity in the visual system for sight recovery.
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Affiliation(s)
- Laura Baroncelli
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy.
| | - Claudia Lunghi
- Laboratoire des systèmes perceptifs, Département d'études cognitives, École normale supérieure, PSL University, CNRS, 75005 Paris, France
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Shivdasani MN, Evans M, Burns O, Yeoh J, Allen PJ, Nayagam DAX, Villalobos J, Abbott CJ, Luu CD, Opie NL, Sabu A, Saunders AL, McPhedran M, Cardamone L, McGowan C, Maxim V, Williams RA, Fox KE, Cicione R, Garrett DJ, Ahnood A, Ganesan K, Meffin H, Burkitt AN, Prawer S, Williams CE, Shepherd RK. In vivo feasibility of epiretinal stimulation using ultrananocrystalline diamond electrodes. J Neural Eng 2020; 17:045014. [PMID: 32659750 DOI: 10.1088/1741-2552/aba560] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE Due to their increased proximity to retinal ganglion cells (RGCs), epiretinal visual prostheses present the opportunity for eliciting phosphenes with low thresholds through direct RGC activation. This study characterised the in vivo performance of a novel prototype monolithic epiretinal prosthesis, containing Nitrogen incorporated ultrananocrystalline (N-UNCD) diamond electrodes. APPROACH A prototype implant containing up to twenty-five 120 × 120 µm N-UNCD electrodes was implanted into 16 anaesthetised cats and attached to the retina either using a single tack or via magnetic coupling with a suprachoroidally placed magnet. Multiunit responses to retinal stimulation using charge-balanced biphasic current pulses were recorded acutely in the visual cortex using a multichannel planar array. Several stimulus parameters were varied including; the stimulating electrode, stimulus polarity, phase duration, return configuration and the number of electrodes stimulated simultaneously. MAIN RESULTS The rigid nature of the device and its form factor necessitated complex surgical procedures. Surgeries were considered successful in 10/16 animals and cortical responses to single electrode stimulation obtained in eight animals. Clinical imaging and histological outcomes showed severe retinal trauma caused by the device in situ in many instances. Cortical measures were found to significantly depend on the surgical outcomes of individual experiments, phase duration, return configuration and the number of electrodes stimulated simultaneously, but not stimulus polarity. Cortical thresholds were also found to increase over time within an experiment. SIGNIFICANCE The study successfully demonstrated that an epiretinal prosthesis containing diamond electrodes could produce cortical activity with high precision, albeit only in a small number of cases. Both surgical approaches were highly challenging in terms of reliable and consistent attachment to and stabilisation against the retina, and often resulted in severe retinal trauma. There are key challenges (device form factor and attachment technique) to be resolved for such a device to progress towards clinical application, as current surgical techniques are unable to address these issues.
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Affiliation(s)
- Mohit N Shivdasani
- Graduate School of Biomedical Engineering, University of New South Wales, Kensington, NSW 2033, Australia. The Bionics Institute of Australia, East Melbourne, VIC 3002, Australia
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Nowik K, Langwińska-Wośko E, Skopiński P, Nowik KE, Szaflik JP. Bionic eye review – An update. J Clin Neurosci 2020; 78:8-19. [DOI: 10.1016/j.jocn.2020.05.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 05/03/2020] [Indexed: 01/26/2023]
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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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Affiliation(s)
- John E Dowling
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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40
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Im M, Kim SW. Neurophysiological and medical considerations for better-performing microelectronic retinal prostheses. J Neural Eng 2020; 17:033001. [PMID: 32329755 DOI: 10.1088/1741-2552/ab8ca9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Maesoon Im
- Center for BioMicrosystems, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea. Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Seoul, Republic of Korea
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Boehler C, Vieira DM, Egert U, Asplund M. NanoPt-A Nanostructured Electrode Coating for Neural Recording and Microstimulation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:14855-14865. [PMID: 32162910 DOI: 10.1021/acsami.9b22798] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bioelectronic devices, interfacing neural tissue for therapeutic, diagnostic, or rehabilitation purposes, rely on small electrode contacts in order to achieve highly sophisticated communication at the neural interface. Reliable recording and safe stimulation with small electrodes, however, are limited when conventional electrode metallizations are used, demanding the development of new materials to enable future progress within bioelectronics. In this study, we present a versatile process for the realization of nanostructured platinum (nanoPt) coatings with a high electrochemically active surface area, showing promising biocompatibility and providing low impedance, high charge injection capacity, and outstanding long-term stability both for recording and stimulation. The proposed electrochemical fabrication process offers exceptional control over the nanoPt deposition, allowing the realization of specific coating morphologies such as small grains, pyramids, or nanoflakes, and can moreover be scaled up to wafer level or batch fabrication under economic process conditions. The suitability of nanoPt as a coating for neural interfaces is here demonstrated, in vitro and in vivo, revealing superior stimulation performance under chronic conditions. Thus, nanoPt offers promising qualities as an advanced neural interface coating which moreover extends to the numerous application fields where a large (electro)chemically active surface area contributes to increased efficiency.
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Affiliation(s)
- Christian Boehler
- Department of Microsystems Engineering (IMTEK)-ElectroActive Coatings Group, University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany
- BrainLinks-BrainTools Center, University of Freiburg, 79110 Freiburg, Germany
| | - Diego M Vieira
- BrainLinks-BrainTools Center, University of Freiburg, 79110 Freiburg, Germany
- Department of Microsystems Engineering (IMTEK)-Laboratory for Biomicrotechnology, University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany
- Bernstein Center Freiburg (BCF), University of Freiburg, 79110 Freiburg, Germany
| | - Ulrich Egert
- BrainLinks-BrainTools Center, University of Freiburg, 79110 Freiburg, Germany
- Department of Microsystems Engineering (IMTEK)-Laboratory for Biomicrotechnology, University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany
- Bernstein Center Freiburg (BCF), University of Freiburg, 79110 Freiburg, Germany
| | - Maria Asplund
- Department of Microsystems Engineering (IMTEK)-ElectroActive Coatings Group, University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany
- BrainLinks-BrainTools Center, University of Freiburg, 79110 Freiburg, Germany
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Kleinlogel S, Vogl C, Jeschke M, Neef J, Moser T. Emerging approaches for restoration of hearing and vision. Physiol Rev 2020; 100:1467-1525. [DOI: 10.1152/physrev.00035.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Impairments of vision and hearing are highly prevalent conditions limiting the quality of life and presenting a major socioeconomic burden. For long, retinal and cochlear disorders have remained intractable for causal therapies, with sensory rehabilitation limited to glasses, hearing aids, and electrical cochlear or retinal implants. Recently, the application of gene therapy and optogenetics to eye and ear has generated hope for a fundamental improvement of vision and hearing restoration. To date, one gene therapy for the restoration of vision has been approved and undergoing clinical trials will broaden its application including gene replacement, genome editing, and regenerative approaches. Moreover, optogenetics, i.e. controlling the activity of cells by light, offers a more general alternative strategy. Over little more than a decade, optogenetic approaches have been developed and applied to better understand the function of biological systems, while protein engineers have identified and designed new opsin variants with desired physiological features. Considering potential clinical applications of optogenetics, the spotlight is on the sensory systems. Multiple efforts have been undertaken to restore lost or hampered function in eye and ear. Optogenetic stimulation promises to overcome fundamental shortcomings of electrical stimulation, namely poor spatial resolution and cellular specificity, and accordingly to deliver more detailed sensory information. This review aims at providing a comprehensive reference on current gene therapeutic and optogenetic research relevant to the restoration of hearing and vision. We will introduce gene-therapeutic approaches and discuss the biotechnological and optoelectronic aspects of optogenetic hearing and vision restoration.
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Affiliation(s)
| | | | | | | | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Goettingen, Germany
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Affiliation(s)
- Diego Ghezzi
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École polytechnique fédérale de Lausanne, Geneva, Switzerland.
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Arens-Arad T, Farah N, Lender R, Moshkovitz A, Flores T, Palanker D, Mandel Y. Cortical Interactions between Prosthetic and Natural Vision. Curr Biol 2019; 30:176-182.e2. [PMID: 31883811 DOI: 10.1016/j.cub.2019.11.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/14/2019] [Accepted: 11/07/2019] [Indexed: 01/15/2023]
Abstract
Outer retinal degenerative diseases, such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD), are among the leading causes of incurable blindness in the Western world [1]. Retinal prostheses have been shown to restore some useful vision by electrically stimulating the remaining retinal neurons [2]. In contrast to inherited retinal degenerative diseases (e.g., RP), typically leading to a complete loss of the visual field, in AMD patients the disease is localized to the macula, leaving the peripheral vision intact. Implanting a retinal prosthesis in the central macula in AMD patients [3, 4] leads to an intriguing situation where the patient's central retina is stimulated electrically, whereas the peripheral healthy retina responds to natural light stimulation. An important question is whether the visual cortex responds to these two concurrent stimuli similarly to the interaction between two adjacent natural light stimuli projected onto healthy retina. Here, we investigated the cortical interactions between prosthetic and natural vision based on visually evoked potentials (VEPs) recorded in rats implanted with photovoltaic subretinal implants. Using this model, where prosthetic and natural vision information are combined in the visual cortex, we observed striking similarities in the interactions of natural and prosthetic vision, including similar effect of background illumination, linear summation of non-patterned stimuli, and lateral inhibition with spatial patterns [5], which increased with target contrast. These results support the idea of combined prosthetic and natural vision in restoration of sight for AMD patients.
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Affiliation(s)
- Tamar Arens-Arad
- Faculty of Life Sciences, School of Optometry and Vision Science, Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel; Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel
| | - Nairouz Farah
- Faculty of Life Sciences, School of Optometry and Vision Science, Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel; Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel
| | - Rivkah Lender
- Faculty of Life Sciences, School of Optometry and Vision Science, Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel; Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel
| | - Avital Moshkovitz
- Faculty of Life Sciences, School of Optometry and Vision Science, Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel; Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel
| | - Thomas Flores
- Hansen Experimental Physics Laboratory, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA; Ophthalmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA
| | - Yossi Mandel
- Faculty of Life Sciences, School of Optometry and Vision Science, Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel; Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Max ve-Anna Webb St, Ramat Gan 5290002, Israel.
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An update on retinal prostheses. Clin Neurophysiol 2019; 131:1383-1398. [PMID: 31866339 DOI: 10.1016/j.clinph.2019.11.029] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 11/23/2022]
Abstract
Retinal prostheses are designed to restore a basic sense of sight to people with profound vision loss. They require a relatively intact posterior visual pathway (optic nerve, lateral geniculate nucleus and visual cortex). Retinal implants are options for people with severe stages of retinal degenerative disease such as retinitis pigmentosa and age-related macular degeneration. There have now been three regulatory-approved retinal prostheses. Over five hundred patients have been implanted globally over the past 15 years. Devices generally provide an improved ability to localize high-contrast objects, navigate, and perform basic orientation tasks. Adverse events have included conjunctival erosion, retinal detachment, loss of light perception, and the need for revision surgery, but are rare. There are also specific device risks, including overstimulation (which could cause damage to the retina) or delamination of implanted components, but these are very unlikely. Current challenges include how to improve visual acuity, enlarge the field-of-view, and reduce a complex visual scene to its most salient components through image processing. This review encompasses the work of over 40 individual research groups who have built devices, developed stimulation strategies, or investigated the basic physiology underpinning retinal prostheses. Current technologies are summarized, along with future challenges that face the field.
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Abstract
In humans high quality, high acuity visual experience is mediated by the fovea, a tiny, specialized patch of retina containing the locus of fixation. Despite this, vision restoration strategies are typically developed in animal models without a fovea. While electrical prostheses have been approved by regulators, as yet they have failed to restore high quality, high acuity vision in patients. Approaches under pre-clinical development include regenerative cell therapies, optogenetics and chemical photosensitizers. All retinal vision restoration therapies require reactivation of inner retina that has lost photoreceptor input and that the restored signals can be interpreted at a behavioural level. A greater emphasis on tackling these challenges at the fovea may accelerate progress toward high quality vision restoration.
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Affiliation(s)
- Juliette E McGregor
- Center for Visual Science, University of Rochester, 601 Crittenden Blvd, Rochester, New York, USA
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Crespo-Cano R, Cuenca-Asensi S, Fernández E, Martínez-Álvarez A. Metaheuristic Optimisation Algorithms for Tuning a Bioinspired Retinal Model. SENSORS (BASEL, SWITZERLAND) 2019; 19:E4834. [PMID: 31698827 PMCID: PMC6891458 DOI: 10.3390/s19224834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/31/2019] [Accepted: 11/03/2019] [Indexed: 11/22/2022]
Abstract
A significant challenge in neuroscience is understanding how visual information is encoded in the retina. Such knowledge is extremely important for the purpose of designing bioinspired sensors and artificial retinal systems that will, in so far as may be possible, be capable of mimicking vertebrate retinal behaviour. In this study, we report the tuning of a reliable computational bioinspired retinal model with various algorithms to improve the mimicry of the model. Its main contribution is two-fold. First, given the multi-objective nature of the problem, an automatic multi-objective optimisation strategy is proposed through the use of four biological-based metrics, which are used to adjust the retinal model for accurate prediction of retinal ganglion cell responses. Second, a subset of population-based search heuristics-genetic algorithms (SPEA2, NSGA-II and NSGA-III), particle swarm optimisation (PSO) and differential evolution (DE)-are explored to identify the best algorithm for fine-tuning the retinal model, by comparing performance across a hypervolume metric. Nonparametric statistical tests are used to perform a rigorous comparison between all the metaheuristics. The best results were achieved with the PSO algorithm on the basis of the largest hypervolume that was achieved, well-distributed elements and high numbers on the Pareto front.
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Affiliation(s)
- Rubén Crespo-Cano
- Department of Computer Technology, University of Alicante, 03690 Alicante, Spain; (R.C.-C.); (S.C.-A.)
| | - Sergio Cuenca-Asensi
- Department of Computer Technology, University of Alicante, 03690 Alicante, Spain; (R.C.-C.); (S.C.-A.)
| | - Eduardo Fernández
- Institute of Bioengineering, University Miguel Hernández and CIBER BBN, 03202 Elche (Alicante), Spain;
| | - Antonio Martínez-Álvarez
- Department of Computer Technology, University of Alicante, 03690 Alicante, Spain; (R.C.-C.); (S.C.-A.)
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Xu LT, Rachitskaya AV, DeBenedictis MJ, Bena J, Morrison S, Yuan A. Correlation between Argus II array-retina distance and electrical thresholds of stimulation is improved by measuring the entire array. Eur J Ophthalmol 2019; 31:194-203. [PMID: 31680546 DOI: 10.1177/1120672119885799] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To describe two methods of measuring Argus II array-retina distance and to correlate array-retina distance to electrode stimulation thresholds. METHODS This was a case series of eight patients implanted with the Argus II. Spectral domain-optical coherence tomography array-retina distance was measured by two methods and correlated to corresponding electrode thresholds: (1) array-retina distance at each array corner and the largest array-retina distance and (2) using manual optical coherence tomography segmentation, the average array-retina distance was determined for each group of four electrodes. Patients 1-5 and 6-8 were analyzed separately due to a different threshold programming software. RESULTS The Spearman's rank coefficient between array-retina distance and thresholds was -0.006 (p = 0.98) for patients 1-5, and 0.16 (p = 0.59) for patients 6-8 with the first method. The Spearman's rank coefficient was 0.25 (p < 0.001) for patients 1-5 and 0.36 (p < 0.001) for patients 6-8 with the second method. CONCLUSION There is a positive correlation between array-retina distance and threshold measurements when measuring the entire array but not when using a faster measurement method of four corners and largest array-retina distance.
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Affiliation(s)
- Lucy T Xu
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | | | | | - James Bena
- Department of Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Shannon Morrison
- Department of Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Alex Yuan
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
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Koch J, Schuettler M, Pasluosta C, Stieglitz T. Electrical connectors for neural implants: design, state of the art and future challenges of an underestimated component. J Neural Eng 2019; 16:061002. [PMID: 31362277 DOI: 10.1088/1741-2552/ab36df] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Technological advances in electrically active implantable devices have increased the complexity of hardware design. In particular, the increasing number of stimulation and recording channels requires innovative approaches for connectors that interface electrodes with the implant circuitry. OBJECTIVE This work aims to provide a common theoretical ground for implantable connector development with a focus on neural applications. APPROACH Aspects and experiences from several disciplines are compiled from an engineering perspective to discuss the state of the art of connector solutions. Whenever available, we also present general design guidelines. MAIN RESULTS Degradation mechanisms, material stability and design rules in terms of biocompatibility and biostability are introduced. Considering contact physics, we address the design and characterization of the contact zone and review contaminants, wear and contact degradation. For high-channel counts and body-like environments, insulation can be even more crucial than the electrical connection itself. Therefore, we also introduce the requirements for electrical insulation to prevent signal loss and distortion and discuss its impact on the practical implementation. SIGNIFICANCE A final review is dedicated to the state of the art connector concepts, their mechanical setup, electrical performance and the interface to other implant components. We conclude with an outlook for possible approaches for the future generations of implants.
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Affiliation(s)
- Julia Koch
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
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Takhchidi KP, Kachalina GF, Takhchidi NK, Manoyan RA, Gliznitsa PV. A bionic eye: performance of the Argus II retinal prosthesis in low-vision and social rehabilitation of patients with end-stage retinitis pigmentosa. BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY 2019. [DOI: 10.24075/brsmu.2019.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The death of outer retinal layers occurring in retinitis pigmentosa causes severe visual impairment and often leads to total blindness. Inner retinal layers are spared, though, which provides a possibility of inducing visual perception by direct electrical stimulation of intact retinal cells. This article presents clinical outcomes of two patients who were the first in Russia to have received the Argus II Retinal Prosthesis System. Both implantations were successful. No complications were reported throughout the entire follow-up period. Upon completing 3 rehabilitation sessions, the patients were able to navigate indoors and outdoors, locate small high-contrast objects, discern contours of large objects and people’s silhouettes.
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Affiliation(s)
- Kh. P. Takhchidi
- Pirogov Russian National Research Medical University, Moscow, Russia
| | - G. F. Kachalina
- Scientific Clinical Center of Otorhinolaryngology, FMBA of Russia, Moscow, Russia
| | - N. Kh. Takhchidi
- Scientific Clinical Center of Otorhinolaryngology, FMBA of Russia, Moscow, Russia
| | - R. A. Manoyan
- Scientific Clinical Center of Otorhinolaryngology, FMBA of Russia, Moscow, Russia
| | - P. V. Gliznitsa
- Pirogov Russian National Research Medical University, Moscow, Russia
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