Hi all,
I’m a new BST user. Maybe this problem has been already posted and solved but I could not find it in the past threads.
Well, I imported 128-sensor EEG recordings in BST directly as EDF averaged files (then already re-sampled, low-pass filtered, artifact-corrected, epoched, etc with Net Station software).
My problem is that when I plot the time-series the waveforms look all right, the amplitude scale too (-8 to 8 microvolt) and the time scale is expressed in seconds, but after running sLORETA source analysis the amplitude scale does not longer show the unit (it goes up to 250 but below values there is written “No Units”).
Then I tried to normalize sLORETA files to baseline and even if I got really nice findings at a cortical level, in this case amplitude scale displays “Invalid scale”.
Now, I’m pretty convinced of the goodness of the analyses I run in BST given that when comparing conditions the results are consistent with literature and with my hypotheses, thus maybe this is just a scale problem not affecting data effects, but I really do not know what I have to report in the source pictures for publication!((:
Is there a way to solve this problem??
Thank you very much and please let me congratulate with you for this beautiful toolbox!
The sLORETA source amplitudes are unit-less since the currents are scaled with respect to the square-root of their covariance. If you standardize the sLORETA solution, the results are still unit less. You could document in your report they are multiples of the baseline standard deviation. The ‘Invalid Scale’ displayed in Brainstorm is a bug: Brainstorm is expecting current amplitudes to be smaller that the values generated by your analysis: we’ll fix that in a future update.
One in the interface, that appeared in June, that was preventing from actually calculating dSPM or sLORETA solutions. It was writing “sLORETA” in the file name, but it was saving the regular wMNE values in it…
One in the colorbar amplitudes, that was leading you to see those “Invalid scales”.
Note that I made a small change in the way the sLORETA values are displayed. The values for this solution are normalized values with amplitude range ~10^-10. Before I was multiplying them by 10^12 when loading the files, then displaying them with this “No units” information.
Now I just show the real value of the sLORETA result.
I’m sorry for all those terrible mistakes. It will probably change a lot what you see on the screen…
The updated version of Brainstorm is online. You can use the menu: Help > Update Brainstorm.
Please contact us again if you are other questions.
Francois