[Eeglablist] Baseline issues, trying again, no pictures this time :-)

[Ilaria Berteletti]

Hello again,

I am hoping for some insight on why my baseline removal is not working.
This time, I am adding a step-by-step explanation of what I'm doing.
(pictures available if needed)

The file I start with is a file that was imported from Brain Vision and
then re-referenced to the mastoids.
When I open to check the "scroll" plot, it appears that a baseline
correction is needed, based on my understanding of Arnaud's tutorials, as
all channels are wide apart and off the plot (ref: 'EEGLAB preprocessing
part 4: Filtering' video).
Using the "remove DC offset" from the plot options, the traces do improve
and nicely show.
I then unflag the plot option (just to make sure although it should have
not changed anything to the file itself) and select the "remove baseline"
option from the drop menu.
If it is relevant, after I click 'OK', I do see the pop-rmbase process show
up in my matlab command window but *no saving GUI pops up *(this shows up
in the video tutorial, maybe differences in version?).

---Command Window text showing up ----
pop_rmbase () : Removing baseline ...
pop_rmbase () : finding continuous data discontinuities
Done.
-------------------------------------------------------

To be sure everything is saved, I manually go in the drop down menu to save
the new file adding a _BL to the end.
When I visualise the "scroll" plot on the newly saved file, nothing has
changed.

Again, my understanding of Arnaud's tutorial was that this operation would
be equivalent to the Remove DC offset option found in the plot menu and
appears to be an important step before filtering.

my question is:
why is this happening?
where am I going wrong?
is the issue in the original file elsewhere?

I have tried running this as a script by saving the history of the baseline
removal and it does not seem to do much.

I would really appreciate any insight as I don't want to simply go on and
process data pretending all is good. Maybe the step is not necessary or the
problem is elsewhere. I'd really like the advice from someone who has more
experience than myself

Thank you,
ilaria



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