[Mne_analysis] time course signs

[Akiko Ikkai]

Hi,

I'm extracting time course from labels, and am wondering if someone could help me understand the following points;

when overlaying a label and examining the time-course in the source wave form display in mne_analyze, I find that the time-course within the label is always positive, even when time courses at each vertex is negative ("retain sign" is checked). Is the time course in a label absolute value of average or max of vertices?

Also, output of Timecourse manager ("save" -> save as *.tim) and inverse solution from the same label using mne_compute_raw_inverse are not identical. I'm curious about why this would be, and whether one output is more suitable for some later analysis than the other. If my ROI labels contain some positive and some negative vertices, is it better to examine time course using mne_analyze (all positive)? 

Thanks in advance, Akiko