noise covariance matrix

Dear MNE specialists,

I am new to MNE and MEG and I am going to analyze coherence on the MEG
data that were originally supposed to be analyzed as averaged ERPs. For
this purpose I need to analyze non-averaged (ongoing, spontaneous ) MEG.
Page 34 of the MNE manual says that in the case of ongoing MEG the noise
covariance matrix should be calculated based on the empty room
measurements. Unfortunately, when the data were collected they were not
supposed to be analyzed as ongoing activity and the empty room
measurements were not done.
Can I still analyze coherence on this data? What kind of noise weighting
can be used in this case?

Elena

Hi Elena

there is an empty room measurement made everyday by the MEG tech, Monday thru Friday, so if you have the dates your subjects were run then we can look up the empty room measurements for that day, I think you can use that file for your the noise covariance matrix.

Deirdre

<elena at nmr.mgh.harvard.edu> 10/30/2007 3:52 PM >>>

Dear MNE specialists,

I am new to MNE and MEG and I am going to analyze coherence on the MEG
data that were originally supposed to be analyzed as averaged ERPs. For
this purpose I need to analyze non-averaged (ongoing, spontaneous ) MEG.
Page 34 of the MNE manual says that in the case of ongoing MEG the noise
covariance matrix should be calculated based on the empty room
measurements. Unfortunately, when the data were collected they were not
supposed to be analyzed as ongoing activity and the empty room
measurements were not done.
Can I still analyze coherence on this data? What kind of noise weighting
can be used in this case?

Elena