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KMID : 1137820080290030231
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의공학회지
2008 Volume.29 No. 3 p.231 ~ p.238
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Magnetoencephalography Source Localization using Improved Downhill Simplex Method in Frequency Domain
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Kim Byeong-Jun
An Kwang-Ok
Jung Hyun-Kyo
Lee Chany
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Abstract
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Nelder-Mead downhill simplex method (DSM), a kind of deterministic optimization algorithms, has been used extensively for magnetoencephalography(MEG) dipolar source localization problems because it dose not require any functional differentiation. Like many other deterministic algorithms, however, it is very sensitive to the choice of initial positions and it can be easily trapped in local optima when being applied to complex inverse problems with multiple simultaneous sources. In this paper, some modifications have been made to make up for DSM’s limitations and improve the accuracy of DSM. First of all, initial point determination method for DSM using magnetic fields on the sensor surface was proposed. Secondly, Univariant-DSM combined DSM with univariant method was proposed. To verify the performance of the proposed method, it was applied to simulated MEG data and practical MEG measurements.
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KEYWORD
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Nelder-Mead downhill simplex method, initial point determination, Univariant method
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