Combining different MEG sensortypes

[Michael Wibral]

Dear Fieldtrip users (with a Neuromag system),

I have a question on how to combine the Information from the planar gradiometers and the magnetometers of a 306 channel Neurmag system best for beamformer weight computation and source time course reconstruction. Do you compute a complete leadfield mixing both types of gradiometers (i.e. you do an unweighted analysis)? Do you somehow weight the sensors for their different noise levels? Do you compute two sets of timecourses (one from grads, one from megnetometers)?
A related question: Do you update the leadfileds for projections that MAxfiltering does (like it should be done when using ICA)?

I am asking because it has been shown that the more sensors are available the better the time course reconstruction (a recent paper by Matthew Brookes). Hence it would be a pity to have to throw some of the information away.

Michael

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