SOFIA: spatially optimal fast initial analysis of biomagnetic signals

A method of analysing biomagnetic signals is presented which focuses attent ion on activity in a specific region of interest. The method is based on th e construction of virtual sensors, corresponding to linear combinations of lead fields that are optimally localized within the region of interest. Thi s method is fast and stable. It is tested against physiologically plausible computer generated signals and also against more elaborate analysis of rea l data. The results show that the method can be very effective as a fast sc anning tool identifying activity from pre-defined regions of interest.