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Optimization of Array Magnetic Coil Design for Functional Magnetic Stimulation Based on Improved Genetic Algorithm | IEEE Journals & Magazine | IEEE Xplore

Optimization of Array Magnetic Coil Design for Functional Magnetic Stimulation Based on Improved Genetic Algorithm


Abstract:

The human brain can be stimulated noninvasively by strong pulses of magnetic field that induce a flow of current in the tissue, leading to the excitation of neurons. Hen...Show More

Abstract:

The human brain can be stimulated noninvasively by strong pulses of magnetic field that induce a flow of current in the tissue, leading to the excitation of neurons. Hence, transcranial magnetic stimulation (TMS) has a wealth of applications in the research, diagnosis and therapy of the brain. The key-point in the stimulation process is to ensure that the effect of the eddy currents evoked in the brain are meeting therapeutical expectations. However, the structure and parameters of the magnetic coils (MC) have very poor relationship with the TMS ability to specifically stimulate the target tissue without activating the surrounding tissues. In this paper, a cone-shaped coil, which consists of two circular coils with a cross angle, is studied and discussed. Furthermore, an array-coil unit which consists of 7 circular coils is also analyzed using an improved adaptive genetic algorithm (IAGA) to search for the optimal parameters of the coils in order to obtain the desired deep and sharp distribution of magnetic fields in deep magnetic stimulation.
Published in: IEEE Transactions on Magnetics ( Volume: 45, Issue: 10, October 2009)
Page(s): 4849 - 4852
Date of Publication: 22 September 2009

ISSN Information:


I. Introduction

TO perform efficient functional magnetic stimulation or to localize the stimulation sites precisely in brain studies, magnetic stimulations are often used. Brain stimulation with transcranial magnetic stimulation (TMS) is achieved from the outside of the head using pulses of electromagnetic field to induce an electric field in the brain [1]. TMS has numerous applications in the study, diagnosis, and therapy of the brain. It is well known that TMS can either excite the cortex or disturb its function. Intense current pulses are driven through a stimulating coil placed above the head, generating a time-varying magnetic field. The poor linkage between the coil and the tissue however limits the efficacy of TMS: only about 10%–30% of the magnetic energy in the coils is transmitted into the nervous tissues. Optimization of the magnetic coil design is therefore necessary in order to improve and optimize TMS. Recent advances in MC configuration have improved the focality (the ability for a coil to stimulate a small target area of the tissue) significantly.

References

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