Which EEG and MEG file formats are supported by BESA?
Click here to download a list of supported file formats.
What is the best strategy to design a multiple source model?
The best strategy is usually a sequential spatio-temporal approach. However, this may depend on the data to be analyzed. For strategies and examples, please read the key papers on multiple source analysis in Publications / Methods.
How can I handle artifacts in BESA?
It is important to get good templates for the topographies of the artifact using pattern search and averaging. Then the topographies can be used as spatial components during source analysis to separate brain from artifactual activities (preferred method). For this load the data segments and the averaged artifacts into the source analysis module and use the PCA on the artifacts to add spatial components to the solution. The second method is based on subspace projection which regressed the artifact topographies out and distorts the topographies during source analysis. Use the artifact correction of the on-going EEG, average and save the corrected averages. When reopening a corrected average file, artifact correction coefficients will be read and automatically used (only in BESA 5.0) for subspace proejction of the data prior to source analysis. In the source analysis module, the forward vectors will be subspace projection and (similarly) distorted. The advantage of the first, preferred method ist that the source waveforms of the artifact and brain signals can be compared to see the epochs of critical interference. Maps are not distorted. The artifact correction of the on-going EEG (second method) contrast the artifact against the background EEG rhythms but not against the much smaller evoked response components to be averaged.
How can I handle artifacts in EEGFocus?
The artifact correction menu in BESA / EEGFocus has been designed to reduce artifacts in the on-going EEG during EEG review without distorting the prominent EEG signals and maps. This can be useful for reducing EKG or frequent eye artifacts such as blinks.
How do I export dipole moments of my fitted sources?
The source waveforms contain the dipole moments of the sources calculated for each time point. Source waveforms can be written to an ASCII file: Use the 'File | Save Source Waveforms As...' menu entry.