Comparison between different approaches to the biomagnetic inverse problem — workshop report

In view of the eminent importance models have for the interpretation of biomagnetic data, it is a matter of concern that a generally accepted strategy for the analysis of experimental data is not in sight. It seems evident that the future prospects of biomagnetic investigations as compared to other functional imaging techniques (e.g. PET, fMRI) will decisively depend on the success of new data analysis techniques. The necessity to develop new modeling strategies is underlined by the fact that the availability of whole-head magnetometer devices necessitates the development of better models: First, more realistic volume conductor models are required, because simple models like a homogeneous sphere are not capable of providing a good approximation if the measurement area Covers the whole head rather than a relatively small area. Second, the number of sources to be considered generally increases with increasing measurement area so that simple source models like the equivalent current dipole become more and more obsolete.