Event Abstract Back to Event The Compressible Estimate (CE) of MEG Current Sources Wei-Tang Chang1* and Fa-Hsuan Lin1 1 National Taiwan University, Institute of Biomedical Engineering, Taiwan Due to the ill-posed nature, MEG inverse problem has no unique solution unless additional constraints are imposed. Since focal and distributed current sources can exist simultaneously or asynchronously, distributed source models using either the minimized l1-norm or l2-norm can inevitably causes biases. Here we introduce the maximal transformed-sparsity estimate (MTSE) source modeling method to localize MEG current sources without explicit preference toward either focal or distributed current source a priori. Inspired by the compressibility of natural images and discrete current loci, MTSE hypothesizes the current sources are spatially focal after a sparsity transformation. MTSE is as an optimization problem with the cost function: min_{s(t)} ||Ms^{l2}(t)||_+α||s^{l2}(t)||_1,s.t.||y(t)-As(t)||_2^2<ε: where M is the sparsity transformation matrix, which can be a Laplacian or wavelet operator. α is the regularization parameter. s_i^{l2}(t)(1<=i<=n) is the local l2-norm at the ith source location and is defined as: s_i^{l2}=||[w_{x,i}s_{x,i}(t) w_{y,i}s_{y,i}(t) w_{z,i}s_{z,i}(t)]||_2: where [w_{x,i}, w_{y,i}, w_{z,i}]=[1/sinθi, 1/sinθi, 1]. θi ranging from 0° to 90° controls the orientation of current sources. ε controls the fidelity of the reconstruction to the measured data.Simulations of MTSEs using Laplacian and wavelet as the sparsity transformation were compared the results from sparce source imaging (SSI) and the minimum norm estimates (MNE). SSI generates globally focal source estimates regardless of the underlying source configurations. MNE generates overly diffused source estimates because of the l2-norm prior. MTSEs provide source estimates without biases toward either a focal or diffused spatial distribution. MTSE is also applied to in vivo MEG auditory and somatosensory experimental data showing both focal and diffused current source estimates. Conference: Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010. Presentation Type: Poster Presentation Topic: MEG Modeling Citation: Chang W and Lin F (2010). The Compressible Estimate (CE) of MEG Current Sources. Front. Neurosci. Conference Abstract: Biomag 2010 - 17th International Conference on Biomagnetism . doi: 10.3389/conf.fnins.2010.06.00059 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Mar 2010; Published Online: 21 Mar 2010. * Correspondence: Wei-Tang Chang, National Taiwan University, Institute of Biomedical Engineering, Taipei, Taiwan, d96548016@ntu.edu.tw Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Wei-Tang Chang Fa-Hsuan Lin Google Wei-Tang Chang Fa-Hsuan Lin Google Scholar Wei-Tang Chang Fa-Hsuan Lin PubMed Wei-Tang Chang Fa-Hsuan Lin Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.