Adjoint method for lead-fields computation in MEEG.

Abstract : Functional brain imaging with M/EEG (Magneto/Electro-EncephaloGraphy) requires first to compute the forward problem whose solution is called lead-field matrix. The lead-field matrix is obtained by concatenating the forward fields computed for thousands of sources characterized by their positions, orientations and strengths. A line of this lead-field matrix represents the physical quantity (potential for EEG, or some components of the magnetic field for MEG) at a sensor for each source. The number of sources largely exceeds the number of sensors (up to 256 electrodes for EEG, and less than 600 squids for MEG). When solving the forward problem with a BEM (Boundary Element Method), the lead-field matrix is generally computed column-by-column, i.e. source by source, which represents nsources resolutions of the forward problem. Using the adjoint operator of the forward problem, one can reduce the computations to nsensors resolutions. Some previous works [5,6,7] have used similar techniques for efficient computation of the lead-fields using finite element methods. The adjoint method [3] generalizes the Helmholtz reciprocity theorem and here is proposed its implementation using the BEM provided by the open-source software OpenMEEG [2] (http://openmeeg.gforge.inria.fr).
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Poster communications
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https://hal.inria.fr/inria-00603769
Contributor : Emmanuel Olivi <>
Submitted on : Monday, June 27, 2011 - 1:11:11 PM
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Emmanuel Olivi, Alexandre Gramfort, Théodore Papadopoulo, Maureen Clerc. Adjoint method for lead-fields computation in MEEG.. HBM'2011, Jun 2011, Québec City, Canada. ⟨inria-00603769⟩

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