MEG Source Imaging Using Multipolar Expansions

We describe the use of truncated multipolar expansions for producing dynamic images of cortical neural activation from measurements of the magnetoencephalogram. We use a signal-subspace method to find the locations of a set of multipolar sources, each of which represents a region of activity in the cerebral cortex. Our method builds up an estimate of the sources in a recursive manner, i.e. we first search for point current dipoles, then magnetic dipoles, and finally first order multipoles. The dynamic behavior of these sources is then computed using a linear fit to the spatiotemporal data. The final step in the procedure is to map each of the multipolar sources into an equivalent distributed source on the cortical surface. The method is demonstrated through a Monte Carlo simulation.

• Type: Conference
• Year: 1999
• Where: IPMI
• Authors: John C. Mosher, Richard M. Leahy, David W. Shattuck, Sylvain Baillet
• Keywords: Cortical Neural Activation, IPMI 1999, Magnetic Dipoles, Medical Imaging, Point Current Dipoles