External Email - Use Caution
Hi Lin,
In a related conversation I was recently reminded that the inverse solution may not be linear when the orientation is loose rather than fixed, maybe that is contributing to the difference?
Ellen
External Email - Use Caution
Hi Ellen,
Thanks for your response. Yeah, as Alex also pointed out, the averaging of
the dSPM values is not linear because of the noise normalization, which
takes the number of epochs into account.
But if we average the MNE values along the 'normal' orientation for the
loose orientation constraints, the operation should be linear, i.e. the
average of MNE values across runs is the same as the MNE of the averaged
ERF across runs.
Best,
Lin
External Email - Use Caution
Hi Lin,
You can use this to bring runs into a common head position (copy-pasted
from Alex's response to an older post):
https://gist.github.com/jasmainak/756cf02dce82ab2dc5c2c69722dd13d1
It's basically using the MNE method on a spherical surface to bring them to
a common head position. I will not vouch for its accuracy compared to
Maxfilter as I have not tested it. However, this is what the 2005 SSS paper
says:
"The problem caused by movement can be solved by using the minimum norm
estimate as a source model for
transforming the measured signals to correspond to a reference head
position. The device-independent components of SSS are a similar source
model with the benefit of modeling also the external interference signals."
I think it's a chicken and an egg problem to some extent. How can you get
an accurate noise covariance to bring the data to a common head position if
the head position is not fixed?
Best,
Mainak