Fabrication of a Miniature Figure-of-Eight Coil for Micromagnetic Stimulation on Neuronal Tissue

doi:10.46620/21-0008

Cited by 3 publications

(2 citation statements)

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“… Jeong et al (2021) designed a figure-eight spiral micro-coil to generate high magnetic flux for ultra-focal stimulation. Saito constructed a figure-eight micro-coil using commercially available chip inductors, which effectively suppressed synchronized bursting activity in a cultured neural network ( Saito, 2021 ). Colella et al (2021) simulated axonal stimulation of peripheral nerves with the figure-eight micro-coil, and found that the threshold for axonal activation was lower for the figure-eight coil than for a circular micro-coil.…”

Section: Introductionmentioning

confidence: 99%

Improving focality and consistency in micromagnetic stimulation

Hall

Hendee

2023

Front. Comput. Neurosci.

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The novel micromagnetic stimulation (μMS) technology aims to provide high resolution on neuronal targets. However, consistency of neural activation could be compromised by a lack of surgical accuracy, biological variation, and human errors in operation. We have recently modeled the activation of an unmyelinated axon by a circular micro-coil. Although the coil could activate the axon, its performance sometimes lacked focality and consistency. The site of axonal activation could shift by several experimental factors, including the reversal of the coil current, displacement of the coil, and changes in the intensity of the stimulation. Current clinical practice with transcranial magnetic stimulation (TMS) has suggested that figure-eight coils could provide better performance in magnetic stimulation than circular coils. Here, we estimate the performance of μMS by a figure-eight micro-coil, by exploring the impact of the same experimental factors on its focality and consistency in axonal activation. We derived the analytical expression of the electric field and activating function generated by the figure-eight micro-coil, and estimated the location of axonal activation. Using NEURON modeling of an unmyelinated axon, we found two different types (A and B) of axon activation by the figure-eight micro-coil, mediated by coil currents of reversed direction. Type A activation is triggered by membrane hyperpolarization followed by depolarization; Type B activation is triggered by direct membrane depolarization. Consequently, the two types of stimulation are governed by distinct ion channel mechanisms. In comparison to the circular micro-coil, the figure-eight micro-coil requires significantly less current for axonal activation. Under figure-eight micro-coil stimulation, the site of axonal activation does not change with the reversal of the coil current, displacement of the coil, or changes in the intensity of the stimulation. Ultimately, the figure-eight micro-coil provides a more efficient and consistent site of activation than the circular micro-coil in μMS.

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Section: Introductionmentioning

confidence: 99%

Improving focality and consistency in micromagnetic stimulation

Hall

Hendee

2023

Front. Comput. Neurosci.

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“…We and colleagues have developed in vivo and in vitro experimental systems with human cells, especially primary stem cells and induced pluripotent stem cells, and have used them to evaluate the biological effects of MF [Takahashi et al, 2017; Saito, 2021; Takahashi and Furuya, 2022]. In this study, we imitated, in vitro, the human B‐cell early differentiation from hematopoietic stem/progenitor cells (HSPCs) using human cord blood‐derived CD34 + (hCD34 + ) cells that have a normal phenotype with the potential to reconstitute hematopoiesis in vivo [Takahashi et al, 2012; Garcia‐Perez et al, 2021].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Effects of Power‐Frequency Magnetic Field Exposure on B‐Cell Differentiation From Human Hematopoietic Stem/Progenitor Cells

Takahashi

Furuya²

2023

Bioelectromagnetics

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The causal relationship between exposure to power‐frequency magnetic fields (MFs) and childhood leukemia has long been controversial. The most common type of childhood leukemia is acute B‐lymphoblastic leukemia caused by abnormal proliferation of B cells in the early differentiation process. Here, we focused on B‐cell early differentiation and aimed to evaluate the effects of exposing cells to power‐frequency MF. First, we optimized an in vitro differentiation protocol of human hematopoietic stem/progenitor cells (HSPCs) to B‐cell lineages. Following validation of the responsiveness of the protocol to additional stimulations and the uniformity of the experimental conditions, human HSPCs were continuously exposed to 300 mT of 50 Hz MF for 35 days of the differentiation process. These experiments were performed in a blinded manner. The percentages of myeloid or lymphoid cells and their degree of differentiation from pro‐B to immature‐B cells in the MF‐exposed group showed no significant changes compared with those in the control group. Furthermore, the expression levels of recombination‐activating gene (RAG)1 and RAG2 in the B cells were also similar to those in the control group. These results indicate that exposure to 50 Hz MF at 300 mT does not affect the human B‐cell early differentiation from HSPCs. © 2023 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.

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