[Eeglablist] biosig function and bio-semi triggers - mystery resolved!

Wed Apr 27 02:09:57 PDT 2011

Hi Alois, Arno,

Yes, BioSig event reader bdf2biosig_events.m in the new versions takes Case
4 as the default option written under the folder:
 /eeglab10_1/external/biosig-partial/t200_FileAccess. I tried this in some
of the later versions of EEGLAB_9 too, and it seems that using this default
option started a while ago.

So, it seems the default Case 4 is a better starting point for reading
events as Alois recommended. I would like to thank Alois again for providing
this support for us.

I have another point to make Arno, it is again related to pre-copmpute
function. I really want to use newer versions of EEGLAB but here what
happens:

In version 9_0_4 the error message was:

Error in ==> eeg_getdatact at 193
        data = data(:,:,opt.trialindices);

Error in ==> std_erp at 158
        EEG(dat).data = eeg_getdatact(EEG(dat), 'channel',
[1:EEG(dat).nbchan], 'rmcomps',
        g.rmcomps{dat}, 'trialindices', g.trialindices{dat});

Error in ==> std_precomp at 196
                std_erp(ALLEEG(desset.dataset), 'channels', tmpchanlist,
opts{:},
                addopts{:}, g.erpparams{:});

Error in ==> fish_study_Adjusted_monotone_50 at 91
[STUDY ALLEEG] = std_precomp(STUDY, ALLEEG,
{},'allcomps','on','recompute','on','erp','on');

In the EEGLAB 10_1 the error message changed into:

??? Error using ==> cell.unique at 47
Input must be a cell array of strings.

Error in ==> std_precomp at 187
        if
length(unique([ALLEEG([STUDY.design(g.design).cell.dataset]).pnts])) > 1

Error in ==> fish_study_Adjusted_monotone_50 at 91
[STUDY ALLEEG] = std_precomp(STUDY, ALLEEG,
{},'allcomps','on','recompute','on','erp','on');

Is this something to do with my settings or a bug ? I still use EEGLAB 7.2
since I believe it is the most stable one for my functions.

Best,
Baris

On Tue, Apr 26, 2011 at 8:02 PM, Arnaud Delorme <arno at ucsd.edu> wrote:

> Dear Baris and others,
>
> EEGLAB 10 contains the latest version of BIOSIG and uses BIOSIG's defaults
> for extracting event information.
> Would you mind making sure that your files are imported as expected using
> this version?
>
> Best regards,
>
> Arno
>
> On Apr 26, 2011, at 2:20 AM, Alois Schloegl wrote:
>
> >
> > Some time ago, based on user feedback, I've already set the default
> > decoding method in biosig/t200/bdf2biosig_events.m also to
> >    case 4 (rising edge, of lower 15 bits)
> > Also for Baris, this mode is working fine.
> >
> > Therefore, I suggest that the default decoding method in eeglab should
> > be also changed to this method, and as used in biosig.
> >
> >
> > Kind regards,
> >    Alois Schloegl
> >
> >
> >
> >
> > On 04/20/11 13:26, Baris Demiral wrote:
> >> Hi everyone,
> >>
> >> I would like to comment on the previous discussion about the biogig
> import
> >> of the bdf files, related to the warnings to some triggers. Some of you
> >> previously reported that you see
> >> the following error messages after importing bdf files with biosig
> function:
> >> Warning SOPEN: number of event onset (TYP=0) and event offset (TYP=8000)
> >> differ (371,366)
> >> Warning SOPEN: number of event onset (TYP=5A) and event offset
> (TYP=805A)
> >> differ (276,280)
> >> Warning SOPEN: number of event onset (TYP=5B) and event offset
> (TYP=805B)
> >> differ (85,88)
> >>
> >> I recognized that this is due to the "response" triggers. Biosig
> >> successfully detects triggers of Stimulus type (first 8 bits of the
> Status
> >> channel) but it is not capable of
> >> detecting the last 8 bits of the Status channel reserved for Response
> coming
> >> mainly from the Switch-boxes.
> >>
> >> That might be the reason why Arno and some other could not replicate
> this
> >> bug, probably because they did not use Biosemi response switch (?). What
> >> happens is that biosig somehow detects the Response trigger, but then it
> >> marks them as "0s". I know that BioSemi marks the off-set of the
> response
> >> switch (release) and puts "0".
> >>
> >> Another reason for the warning might be that when you use response
> boxes, as
> >> well as recording, say, accuracy by looking at the response, and send
> >> triggers to eeg machine before the button release, they may add up and
> give
> >> you weird trigger codes. But, the codes are not arbitrary and can be
> easily
> >> converted.
> >>
> >> Any comments? Anyone responsible for the Biosig function, could you
> reply
> >> please?
> >>
> >> Best,
> >> Baris
> >>
> >>
> >>
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-- 
SB Demiral, PhD.
Department of Psychology
7 George Square
The University of Edinburgh
Edinburgh, EH8 9JZ
UK
Phone: +44 (0131) 6503063
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