Open AccessReconstruction of extended cortical sources for EEG and MEG based on a Monte‐Carlo‐Markov‐chain estimator
Author(s) -
Kincses Wilhelm Emil,
Braun Christoph,
Kaiser Stefan,
Grodd Wolfgang,
Ackermann Hermann,
Mathiak Klaus
Publication year - 2003
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/hbm.10079
Subject(s) - estimator , markov chain monte carlo , maximum a posteriori estimation , computer science , noise (video) , markov chain , probabilistic logic , electroencephalography , pattern recognition (psychology) , algorithm , artificial intelligence , bayesian probability , mathematics , statistics , maximum likelihood , psychology , machine learning , neuroscience , image (mathematics)
A new procedure to model extended cortical sources from EEG and MEG recordings based on a probabilistic approach is presented. The method (SPMECS) was implemented within the framework of maximum likelihood estimators. Neuronal activity generating EEG or MEG signals was characterized by the number of sources and their location and extension. Based on the noise distribution of the measured data, source configurations were associated with the according value of the likelihood function. To find the most likely source, i.e., the maximum likelihood estimator, and its level of confidence, a stochastic solver (Metropolis algorithm) was applied. The method presented supports the incorporation of virtually any constraint, e.g., based on physiological and anatomical a priori knowledge. Thus, ambiguity of the ill‐posed inverse problem was reduced considerably by confining sources to the cortical surface extracted from individual MR images. The influence of different levels and types of noise on the outcome was investigated by means of simulations. Somatosensory evoked magnetic fields analyzed by the method presented suggest that larger extended cortical areas are involved in the processing of combined finger stimulation as compared to single finger stimulation. Hum. Brain Mapping 18:100–110, 2003. © 2002 Wiley‐Liss, Inc.