Estimation of locations of multiple sources in a multi-layer volume conductor using medium filters

An estimate is made of the number and locations of planar bioelectric sources in a horizontally layered volume conductor, from noisy surface measurements of electrical potential on a plane. The effects of the volume conductor are modeled by a medium filter, a 2-D filter which relates the potential on one plane to the potential on another plane; this permits simple regularization. The location estimation problem can then be formulated as a multiple hypothesis minimum error probability generalized likelihood ratio test. Numerical results are presented. The Cramer-Rao bound on the variance of any unbiased depth estimator is discussed to interpret the results