Implantable microcoils for intracortical magnetic stimulation

Lee, Seung Woo; Fallegger, Florian; Casse, B. D. F.; Fried, Shelley I.

doi:10.1126/sciadv.1600889

Cited by 132 publications

(194 citation statements)

References 60 publications

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“…The size of the coils, number of turns, their magnetic core, and locations with respect to the brain are optimized in a way that fulfil multiple objectives: a) the size of the coils and their locations with respect to the brain should be optimized such that the produced magnetic fields by two coils can interfere at any area and any depth inside the brain with a high spatial resolution. Unlike TMS technique, which can only stimulate the peripheral regions and lacks a high spatial resolution, MTI technique can focus the magnetic or electric fields at deep brain area; b) the generated electric field gradient, which is the most important parameter for magnetic brain stimulation, should be higher than the threshold value required for brain stimulation, which is about 11k V/m 2 [12,13]; c) the designed coils should be able to efficiently operate at frequencies up to 50kHz. This is because the induced electric field of the coils increases linearly by increasing the operational frequency, meaning that we can generate very large electric fields and go above required threshold value by increasing the frequency and without increasing the current, heavily reducing the generated heat and power consumption.…”

Section: -Design Simulation and Concept Validation Of Magnetic Temmentioning

confidence: 99%

Magnetic Temporal Interference For Noninvasive, High-resolution, and Localized Deep Brain Stimulation: Concept Validation

Zaeimbashi

Khalifa

Dong

et al. 2020

Preprint

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Non-invasive deep brain stimulation has been a major challenge in the field of neuroscience and brain stimulation in the past three decades. Current brain stimulation technologies suffer from such hurdles as the inability to do deep brain stimulation, poor spatial resolution, and invasiveness. Transcranial magnetic stimulation (TMS) technique, for instance, cannot target brain regions deeper than ∼2cm and has a poor spatial resolution, impacting a large area of the peripheral region and leading to various side effects. Implantable electrodes, even though effective for deep brain stimulation, are invasive and carry various drawbacks related to the surgery and site infection. In this paper, we propose a new concept that relies on temporal interference of two high- frequency magnetic fields generated by two electromagnetic coils. The neural system does not respond to each of these high-frequency magnetic fields alone because of the intrinsic low-pass filtering properties of the neural membrane. The peripheral areas of the brain are impacted only by the high-frequency magnetic fields that cannot stimulate the nerves, while the deep brain area where the two fields interfere experiences a magnetic field that contains a low-frequency envelope and therefore the nerves can be stimulated. This technique can noninvasively focus a magnetic or electric beam at any depth inside the brain with a high resolution, without impacting the peripheral regions.

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Section: -Design Simulation and Concept Validation Of Magnetic Temmentioning

confidence: 99%

Magnetic Temporal Interference For Noninvasive, High-resolution, and Localized Deep Brain Stimulation: Concept Validation

Zaeimbashi

Khalifa

Dong

et al. 2020

Preprint

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“…Additionally, other researchers are starting to use magnetic stimulation from implantable micro-coils as an alternative to conventional micro-electrodes. Coils are attractive because they overcome many of the limitations of conventional electrodes since magnetic stimulation does not require the injection of electrical currents and asymmetric fields from coils can be used to improve focal activation of specific subsets of neurons (Lee et al, 2016).…”

Section: Electrode-to-tissue Interface Issuesmentioning

confidence: 99%

Development of visual Neuroprostheses: trends and challenges

Fernández

2018

Bioelectron Med

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Visual prostheses are implantable medical devices that are able to provide some degree of vision to individuals who are blind. This research field is a challenging subject in both ophthalmology and basic science that has progressed to a point where there are already several commercially available devices. However, at present, these devices are only able to restore a very limited vision, with relatively low spatial resolution. Furthermore, there are still many other open scientific and technical challenges that need to be solved to achieve the therapeutic benefits envisioned by these new technologies. This paper provides a brief overview of significant developments in this field and introduces some of the technical and biological challenges that still need to be overcome to optimize their therapeutic success, including long-term viability and biocompatibility of stimulating electrodes, the selection of appropriate patients for each artificial vision approach, a better understanding of brain plasticity and the development of rehabilitative strategies specifically tailored for each patient.

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“…Although subretinal 344 prostheses such as Alpha-IMS (Stingl et al, 2015) have electrodes in close proximity to bipolar 345 cells, in vitro animal studies have found that subretinal stimulation with 1 ms pulses also directly 346 activates retinal ganglion cells at thresholds statistically similar to those of inner retinal cells 347 (Boinagrov et al, 2014;Eickenscheidt et al, 2012;Tsai et al, 2009). Similarly, axonal stimulation 348 is expected to be an issue for cortical implants, since passing axons from neurons located in distant 349 parts of the brain have been shown to be highly sensitive to electrical stimulation (Histed et al,350 2009; Lee et al, 2016;Ranck, 1975). 351…”

Section: Phosphene Shape Is Mediated By Axonal Stimulation 331mentioning

confidence: 99%

A model of ganglion axon pathways accounts for percepts elicited by retinal implants

Beyeler

Nanduri

Weiland

et al. 2018

Preprint

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12Degenerative retinal diseases such as retinitis pigmentosa and macular degeneration cause 13 irreversible vision loss in more than 10 million people worldwide. Retinal prostheses, now 14 implanted in more than 250 patients worldwide, electrically stimulate surviving cells in order to 15 evoke neuronal responses that are interpreted by the brain as visual percepts ('phosphenes'). 16However, instead of seeing focal spots of light, users of current epiretinal devices perceive highly 17 distorted phosphenes, which vary in shape not just across subjects but also across electrodes, 18 resulting in distorted percepts. We characterized these distortions by asking users of the Argus 19retinal prosthesis system (Second Sight Medical Products, Inc.) to draw percepts elicited by single-20 electrode stimulation on a touchscreen. Based on ophthalmic fundus photographs, we then 21 developed a computational model of the topographic organization of optic nerve fiber bundles in 22 each subject's retina, and used this model to successfully simulate predicted patient percepts. Our 23 model shows that activation of passing axon fibers contributes to the rich repertoire of phosphene 24shapes reported by patients in our psychophysical measurements, successfully replicating visual 25 percepts ranging from 'blobs' to oriented 'streaks' and 'wedges' depending on the retinal location 26 of the stimulating electrode. This model provides a first step towards future devices that 27 incorporate stimulation strategies tailored to each individual patient's retinal neurophysiology. 28 Impact 29 Current retinal implant users report seeing distorted and often elongated shapes rather than small 30 focal spots of light that match the shape of the implant electrodes. Here we show that the perceptual 31 experience of retinal implant users can be accurately predicted using a computational model that 32simulates each individual patient's retinal ganglion axon pathways. This opens up the possibility 33 for future devices that incorporate stimulation strategies tailored to each individual patient's retina. 34Wuyyuru, V., Sahel, J., Stanga, P., et al. (2013). The Argus II epiretinal prosthesis system allows 595 letter and word reading and long-term function in patients with profound vision loss. Br J 596Ophthalmol 97, 632-636. 597

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Implantable microcoils for intracortical magnetic stimulation

Abstract: Magnetic stimulation from cortically implantable microcoils can activate neuronal circuits with high selectivity and reliability.

Cited by 132 publications

References 60 publications

Magnetic Temporal Interference For Noninvasive, High-resolution, and Localized Deep Brain Stimulation: Concept Validation

Magnetic Temporal Interference For Noninvasive, High-resolution, and Localized Deep Brain Stimulation: Concept Validation

Development of visual Neuroprostheses: trends and challenges

A model of ganglion axon pathways accounts for percepts elicited by retinal implants

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