Kinematic visualization of human magnetic encephalography

A method is presented for the analysis of magneto-encephalographic (MEG) data from a cognitive study involving auditory activity in humans. Signal averaging based on the moment of stimulus onset was used to extract the evoked magnetic field from the spontaneous activity. Positions and dipole moment estimation for auditory sources i.e. “the inverse problem” was addressed for each time point in the interstimulus interval. Two field-map sequences were generated, one corresponding to the direct magnetic field responses over the head and the other to the inverse-problem solutions and software developed for simultaneously field map superposition (SFMS). SFMS, included whole-head tomography, stimulus time series, auditory evoked fields and inverse-problem solutions. A computer movie was created to provide an accessible overview of magnetic-encephalography methods and to demonstrate its application to auditory research. The methods and software developed are applicable to other MEG recording sets.