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Ahtiainen A, Leydolph L, Tanskanen JMA, Hunold A, Haueisen J, Hyttinen JAK. Electric field temporal interference stimulation of neurons in vitro. LAB ON A CHIP 2024; 24:3945-3957. [PMID: 38994783 DOI: 10.1039/d4lc00224e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
Electrical stimulation (ES) techniques, such as deep brain and transcranial electrical stimulation, have shown promise in alleviating the symptoms of depression and other neurological disorders in vivo. A new noninvasive ES method called temporal interference stimulation (TIS), possesses great potential as it can be used to steer the stimulation and possibly selectively modulate different brain regions. To study TIS in a controlled environment, we successfully established an in vitro 'TIS on a chip' setup using rat cortical neurons on microelectrode arrays (MEAs) in combination with a current stimulator. We validated the developed TIS system and demonstrated the spatial steerability of the stimulation by direct electric field measurements in the chip setup. We stimulated cultures of rat cortical neurons at 28 days in vitro (DIV) by two-channel stimulation delivering 1) TIS at 653 Hz and 643 Hz, resulting in a 10 Hz frequency envelope, 2) low-frequency stimulation (LFS) at 10 Hz and 3) high-frequency stimulation (HFS) at 653 Hz. Unstimulated cultures were used as control/sham. We observed the differences in the electric field strengths during TIS, HFS, and LFS. Moreover, HFS and LFS had the smallest effects on neuronal activity. Instead, TIS elicited neuronal electrophysiological responses, especially 24 hours after stimulation. Our 'TIS on a chip' approach eludicates the applicability of TIS as a method to modulate neuronal electrophysiological activity. The TIS on a chip approach provides spatially steerable stimuli while mitigating the effects of high stimulus fields near the stimulation electrodes. Thus, the approach opens new avenues for stimulation on a chip applications, allowing the study of neuronal responses to gain insights into the potential clinical applications of TIS in treating various brain disorders.
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Affiliation(s)
- Annika Ahtiainen
- Faculty of Medicine and Health Technology, Tampere University, 33520, Tampere, Finland.
| | - Lilly Leydolph
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany
| | - Jarno M A Tanskanen
- Faculty of Medicine and Health Technology, Tampere University, 33520, Tampere, Finland.
| | - Alexander Hunold
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany
- neuroConn GmbH, 98693, Ilmenau, Germany
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany
- Department of Neurology, Jena University Hospital, 07747 Jena, Germany
| | - Jari A K Hyttinen
- Faculty of Medicine and Health Technology, Tampere University, 33520, Tampere, Finland.
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Thiele C, Rufener KS, Repplinger S, Zaehle T, Ruhnau P. Transcranial temporal interference stimulation (tTIS) influences event-related alpha activity during mental rotation. Psychophysiology 2024:e14651. [PMID: 38997805 DOI: 10.1111/psyp.14651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 05/14/2024] [Accepted: 07/01/2024] [Indexed: 07/14/2024]
Abstract
Non-invasive brain stimulation techniques offer therapeutic potential for neurological and psychiatric disorders. However, current methods are often limited in their stimulation depth. The novel transcranial temporal interference stimulation (tTIS) aims to overcome this limitation by non-invasively targeting deeper brain regions. In this study, we aimed to evaluate the efficacy of tTIS in modulating alpha activity during a mental rotation task. The effects of tTIS were compared with transcranial alternating current stimulation (tACS) and a sham control. Participants were randomly assigned to a tTIS, tACS, or sham group. They performed alternating blocks of resting and mental rotation tasks before, during, and after stimulation. During the stimulation blocks, participants received 20 min of stimulation adjusted to their individual alpha frequency (IAF). We assessed shifts in resting state alpha power, event-related desynchronization (ERD) of alpha activity during mental rotation, as well as resulting improvements in behavioral performance. Our results indicate tTIS and tACS to be effective in modulating cortical alpha activity during mental rotation, leading to an increase in ERD from pre- to poststimulation as well as compared to sham stimulation. However, this increase in ERD was not correlated with enhanced mental rotation performance, and resting state alpha power remained unchanged. Our findings underscore the complex nature of tTIS and tACS efficacy, indicating that stimulation effects are more observable during active cognitive tasks, while their impacts are less pronounced on resting neuronal systems.
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Affiliation(s)
- Carsten Thiele
- Department of Neurology, Otto-von-Guericke-University, University Clinic of Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
| | - Katharina S Rufener
- Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
- Department of Psychiatry, Psychotherapy and Psychosomatic Medicine of Childhood and Adolescents, Otto-von-Guericke-University, University Clinic of Magdeburg, Magdeburg, Germany
| | - Stefan Repplinger
- Department of Neurology, Otto-von-Guericke-University, University Clinic of Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
| | - Tino Zaehle
- Department of Neurology, Otto-von-Guericke-University, University Clinic of Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
| | - Philipp Ruhnau
- Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
- School of Psychology and Humanities, University of Central Lancashire, Preston, UK
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Mojiri Z, Akhavan A, Rouhani E, Zahabi SJ. Quantitative analysis of noninvasive deep temporal interference stimulation: A simulation and experimental study. Heliyon 2024; 10:e29482. [PMID: 38655334 PMCID: PMC11035070 DOI: 10.1016/j.heliyon.2024.e29482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/26/2024] Open
Abstract
Background Deep brain stimulation (DBS) is a method for stimulating deep regions of the brain for the treatment of various neurological and psychiatric disorders such as depression, obsessive-compulsive disorder, addiction, and Parkinson's disease. Generally, DBS can be performed using both invasive and non-invasive approaches. Invasive DBS is associated with several problems, including intracranial bleeding, infection, and changes in the position of the electrode tip. Temporal interference (TI) stimulation is a non-invasive technique used to stimulate deep regions of the brain by applying two high-frequency sinusoidal currents with slightly different frequencies. New method This paper presents insights into the response of the spiking in the Hodgkin-Huxley (HH) neuron model of the rat somatosensory cortex by changing the parameters carrier frequency, current ratio, and difference frequency of TI stimulation. Furthermore, in order to experimentally evaluate the effect of TI stimulation on the activation of the left motor cortex, an experiment was conducted to measure the motion induced by the balanced and unbalanced TI stimulation. In the experiment, a three-axis accelerometer was attached to the right hand of the animal to determine the position of the hand. Results Simulation results of the HH model showed that the frequency of the envelope of the TI stimulation is identical to the fundamental frequency of the neuron spikes. This result was obtained for difference frequencies of 6 Hz and 9 Hz in balanced and unbalanced TI stimulations. Moreover specifically, when the difference frequency is set to zero, the carrier frequency is within the range of 1300-1400 Hz, and the current range is between 140 and 250 μA/cm2, the firing rate reached to its highest value. In the experimental result, the maximum range of movement at a difference frequency of Δf = 6 Hz was approximately 1.6 mm and 5.3 mm in the z and y directions respectively. Comparison with existing method The results of the spatial spectrum of the rat hand movement were consistent with the spectrum information of the simulation results. Additionally, steering the interfering region to the left motor cortex leads to noticeable contralateral movement of the right hand while no movement was observed in the right hand during the stimulation of the right motor cortex. Conclusion This technique of stimulation for the deep regions of the brain is a promising tool to noninvasively treat various neurological and psychiatric disorders such as morphine dependence in addicted rats.
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Affiliation(s)
- Zohre Mojiri
- Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Amir Akhavan
- Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Ehsan Rouhani
- Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Sayed Jalal Zahabi
- Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
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Ma S, Song X, Guo T, Zhou F, Liu Z, Chai X, Li L. Improving Spatial Resolution and Selectivity of Transcorneal Electrical Stimulation by Temporal Interference Technology. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083661 DOI: 10.1109/embc40787.2023.10341049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Transcorneal electrical stimulation (TES) used in a therapeutic device has been demonstrated significant neuroprotective effect for rescuing retinal function. However, the diffuse electric field induced by conventional TES devices reduced their spatial resolution and selectivity, limiting their capability of actively stimulating a severely diseased retina. A cutting-edge neuromodulation approach named temporal interference stimulation (TIS) was reported to induce electric fields focalizing on local neuronal targets. Despite the competent feasibility of application in retinal TIS, the interpretation of characteristics of spatial resolution and selectivity under TIS remains rudimentary. In this study, we conduct in silico investigations to understand the characteristics of spatial selectivity and resolution using a finite element model of a multi-layered eyeball and multiple electrode configuration. By simulating different metrics of electric potentials envelope modulated by TIS, our model supports the possibility of achieving mini-invasive and spatially selective electrical stimulation using retinal TIS. These simulations provide theoretical evidence on the basis of which sophisticated devices for improved spatial selectivity can be designed.Clinical Relevance- This study provides a theoretical basis for understanding how the design of electrode configuration impacts transcorneal TIS performance. This model can guide future development of transcorneal TIS configurations and stimulation strategies that may benefit patients with inherited retinal diseases.
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Guo W, He Y, Zhang W, Sun Y, Wang J, Liu S, Ming D. A novel non-invasive brain stimulation technique: "Temporally interfering electrical stimulation". Front Neurosci 2023; 17:1092539. [PMID: 36777641 PMCID: PMC9912300 DOI: 10.3389/fnins.2023.1092539] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/17/2023] [Indexed: 01/30/2023] Open
Abstract
For decades, neuromodulation technology has demonstrated tremendous potential in the treatment of neuropsychiatric disorders. However, challenges such as being less intrusive, more concentrated, using less energy, and better public acceptance, must be considered. Several novel and optimized methods are thus urgently desiderated to overcome these barriers. In specific, temporally interfering (TI) electrical stimulation was pioneered in 2017, which used a low-frequency envelope waveform, generated by the superposition of two high-frequency sinusoidal currents of slightly different frequency, to stimulate specific targets inside the brain. TI electrical stimulation holds the advantages of both spatial targeting and non-invasive character. The ability to activate deep pathogenic targets without surgery is intriguing, and it is expected to be employed to treat some neurological or psychiatric disorders. Recently, efforts have been undertaken to investigate the stimulation qualities and translation application of TI electrical stimulation via computational modeling and animal experiments. This review detailed the most recent scientific developments in the field of TI electrical stimulation, with the goal of serving as a reference for future research.
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Affiliation(s)
- Wanting Guo
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Yuchen He
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Wenquan Zhang
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Yiwei Sun
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Junling Wang
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Shuang Liu
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China,*Correspondence: Shuang Liu,
| | - Dong Ming
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China,Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China,Tianjin International Joint Research Center for Neural Engineering, Tianjin, China,Dong Ming,
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Guo T, Chang YC, Li L, Dokos S, Li L. Editorial: Advances in bioelectronics and stimulation strategies for next generation neuroprosthetics. Front Neurosci 2023; 16:1116900. [PMID: 36704005 PMCID: PMC9872720 DOI: 10.3389/fnins.2022.1116900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/13/2022] [Indexed: 01/11/2023] Open
Affiliation(s)
- Tianruo Guo
- Graduate School of Biomedical Engineering, The University of New South Wales Sydney, Sydney, NSW, Australia
| | - Yao-chuan Chang
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, United States,Medtronic PLC, Minneapolis, MN, United States
| | - Luming Li
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, China,Precision Medicine and Healthcare Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen, China,IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, The University of New South Wales Sydney, Sydney, NSW, Australia
| | - Liming Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China,*Correspondence: Liming Li ✉
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Bahn S, Lee C, Kang B. A computational study on the optimization of transcranial temporal interfering stimulation with high-definition electrodes using unsupervised neural networks. Hum Brain Mapp 2022; 44:1829-1845. [PMID: 36527707 PMCID: PMC9980883 DOI: 10.1002/hbm.26181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
Transcranial temporal interfering stimulation (tTIS) can focally stimulate deep parts of the brain related to specific functions using beats at two high frequencies that do not individually affect the human brain. However, the complexity and nonlinearity of the simulation limit it in terms of calculation time and optimization precision. We propose a method to quickly optimize the interfering current value of high-definition electrodes, which can finely stimulate the deep part of the brain, using an unsupervised neural network (USNN) for tTIS. We linked a network that generates the values of electrode currents to another network, which is constructed to compute the interference exposure, for optimization by comparing the generated stimulus with the target stimulus. Further, a computational study was conducted using 16 realistic head models. We also compared tTIS with transcranial alternating current stimulation (tACS), in terms of performance and characteristics. The proposed method generated the strongest stimulation at the target, even when targeting deep areas or performing multi-target stimulation. The high-definition tTISl was less affected than tACS by target depth, and mis-stimulation was reduced compared with the case of using two-pair inferential stimulation in deep region. The optimization of the electrode currents for the target stimulus could be performed in 3 min. Using the proposed USNN for tTIS, we demonstrated that the electrode currents of tTIS can be optimized quickly and accurately. Moreover, we confirmed the possibility of precisely stimulating the deep parts of the brain via transcranial electrical stimulation.
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Affiliation(s)
- Sangkyu Bahn
- Cognitive Science Research GroupKorea Brain Research InstituteDaeguRepublic of Korea
| | - Chany Lee
- Cognitive Science Research GroupKorea Brain Research InstituteDaeguRepublic of Korea
| | - Bo‐Yeong Kang
- School of ConvergenceKyungpook National UniversityDaeguRepublic of Korea
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Lu Z, Zhou M, Guo T, Liang J, Wu W, Gao Q, Li L, Li H, Chai X. An in-silico analysis of retinal electric field distribution induced by different electrode design of trans-corneal electrical stimulation. J Neural Eng 2022; 19. [PMID: 36044887 DOI: 10.1088/1741-2552/ac8e32] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/31/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Trans-corneal electrical stimulation (TcES) produces therapeutic effects on many ophthalmic diseases non-invasively. Existing clinical TcES devices use largely variable design of electrode distribution and stimulation parameters. Better understanding of how electrode configuration paradigms and stimulation parameters influence the electric field distribution on the retina, will be beneficial to the design of next-generation TcES devices. APPROACH In this study, we constructed a realistic finite element human head model with fine eyeball structure. Commonly used DTL-Plus and ERG-Jet electrodes were simulated. We then conducted in silico investigations of retina observation surface (ROS) electric field distributions induced by different return electrode configuration paradigms and different stimulus intensities. MAIN RESULTS Our results suggested that the ROS electric field distribution could be modulated by re-designing TcES electrode settings and stimulus parameters. Under far return location (FRL) paradigms, either DTL-Plus or ERG-Jet approach could induce almost identical ROS electric field distribution regardless where the far return was located. However, compared with the ERG-Jet mode, DTL-Plus stimulation induced stronger nasal lateralization. In contrast, ERG-Jet stimulation induced relatively stronger temporal lateralization. The ROS lateralization can be further tweaked by changing the DTL-Plus electrode length. SIGNIFICANCE These results may contribute to the understanding of the characteristics of DTL-Plus and ERG-Jet electrodes based electric field distribution on the retina, providing practical implications for the therapeutic application of TcES.
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Affiliation(s)
- Zhuofan Lu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai, Shanghai, 200240, CHINA
| | - Meixuan Zhou
- Shanghai Jiao Tong University, Shanghai 200240, Shanghai, 200240, CHINA
| | - Tianruo Guo
- GSBME, University of New South Wales, Graduate School of Biomedical Engineering, University of New South Wales, NSW 2052, Sydney, Australia, Sydney, New South Wales, 2052, AUSTRALIA
| | - Junling Liang
- Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai Shanghai, CN 200240, Shanghai, 200240, CHINA
| | - Weilei Wu
- Shanghai Jiao Tong University, School of Biomedical Engineering Shanghai Jiao Tong University , Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang District, Shanghai Shanghai, CN 200240, Shanghai, 200240, CHINA
| | - Qi Gao
- Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai, Shanghai, 200240, CHINA
| | - Liming Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, Shanghai, 200240, CHINA
| | - Heng Li
- Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai Shanghai, CN 200240, Shanghai, 200240, CHINA
| | - Xinyu Chai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, Shanghai, 200240, CHINA
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Su X, Zhou M, Di L, Chen J, Zhai Z, Liang J, Li L, Li H, Chai X. The Visual Cortical Responses to Sinusoidal Transcorneal Electrical Stimulation. Brain Res 2022; 1785:147875. [PMID: 35271821 DOI: 10.1016/j.brainres.2022.147875] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 11/25/2022]
Abstract
Retinal stimulation has become a widely utilized approach to restore visual function for individuals with retinal degenerative diseases. Although the rectangular electrical pulse is the primary stimulus waveform used in retinal neuromodulation, it remains unclear whether alternate waveforms may be more effective. Here, we used the optical intrinsic signal imaging system to assess the responses of cats' visual cortex to sinusoidal electrical stimulation through contact lens electrode, analyzing the response to various stimulus parameters (frequency, intensity, pulse width). A comparison between sinusoidal and rectangular stimulus waveform was also investigated. The results indicated that the optimal stimulation frequency for sinusoidal electrical stimulation was approximately 20 Hz, supporting the hypothesis that low-frequency electrostimulation induces more responsiveness in retinal neurons than high-frequency electrostimulation in case of sinusoidal stimulation. We also demonstrated that for low-frequency retinal neuromodulation, sinusoidal pulses are more effective than rectangular ones. In addition, we found that compared to current intensity, the effect of the sinusoidal pulse width on cortical responses was more prominent. These results suggested that sinusoidal electrical stimulation may provide a promising strategy for improved retinal neuromodulation in clinical settings.
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Affiliation(s)
- Xiaofan Su
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Meixuan Zhou
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Liqing Di
- Department of Orthopedics, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China
| | - Jianpin Chen
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zhenzhen Zhai
- The Network & Information Center, Shanghai Jiao Tong University, Shanghai, China
| | - Junling Liang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Liming Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Heng Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Xinyu Chai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
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Terasawa Y, Tashiro H, Ueno T, Ohta J. Precise temporal control of interferential neural stimulation via phase modulation. IEEE Trans Biomed Eng 2021; 69:220-228. [PMID: 34161235 DOI: 10.1109/tbme.2021.3091689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Noninvasive neural stimulation via temporally interferential (TI) electrical field is currently an area of interest as a noninvasive method of brain stimulation. The major limitation of TI stimulation is the difficulty of precise temporal control of the stimulation, due to the nature of the sinusoidal envelope generated by the interference. The purpose of this study was to investigate the possibility of improving interferential stimulation by introducing precise temporal control using phase modulation. METHODS In conventional TI, a sinusoidal current is applied to two electrode pairs with slightly different frequencies, to cause interference. In this paper we describe phase modulation interference (PMI). Instead of shifting frequency, the phase of a sinusoidal wave was partially modulated, causing a transient increase or decrease of the envelope. The spatial distribution of envelope modulation amplitude by TI and PMI was visualized using both electromagnetic simulation and actual measurement using tissue phantom. RESULTS The measured voltage transient in the tissue phantom produce a precise, temporally controlled pulse-like envelope using PMI. The spatial distributions of the amplitude of the envelope modulation by TI and PMI did not differ significantly, and were consistent with electromagnetic simulation. CONCLUSION PMI allows precise temporal control of interferential stimulation, thus increasing the practical utility of interferential stimulation. SIGNIFICANCE PMI improves interferential stimulation, allowing more temporally precise stimulation to neural tissue located distantly from the stimulating electrodes.
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