[Eeglablist] Shifted rejection boundaries in continuous data
Maria Teresa Wijaya
a0089301 at nus.edu.sg
Tue Jan 8 19:11:40 PST 2013
Hi James and Makoto,
I tried quickly clicking >> twice on the channel data scroll page with
three different datasets but did not see the error you described. I
don't think it is very likely to be the cause of the shift in my case
since I always use the > button to scroll through my data, also if the
display is refreshed after further interaction I don't think it would
result in the permanent shift which is still there after the data is
saved into new file.
I also had another probably related problem after epoching the data. It
seemed that a rejection boundary marker was not recognized and as a
result the stretch of discontinuous data was treated as continuous and
included as a valid epoch (e.g.:
http://www.flickr.com/photos/89964745@N02/8363588406/in/photostream). I
ran James' script to see if my event markers were shifted, but they did
not seem to be affected and the subject ERP also looked fine to me.
Here's the script that I used for the epoching:
%%%%%epoch & baseline correction
EEG = pop_epoch(EEG, {'122', '121', '120', '220', '210', '200'}, ...
[-0.15 1], 'savenew', 'BDF file resampled epochs', 'epochinfo','yes');
EEG=pop_rmbase(EEG,[],[1:38]); %be sure to put a negative number for
the starting point of the baseline.
EEG=eeg_checkset(EEG);
v = [EEG.event.epoch];
allepochs = v(end);
%%%%%%reject
EEG = pop_jointprob(EEG,1,PROB,PROB,0,0);
EEG = eeg_rejsuperpose( EEG, 1, 1, 1, 1, 1, 1, 1, 1);
EEG = pop_rejepoch(EEG, find(EEG.reject.rejglobal), 0);
v = [EEG.event.epoch];
cleanedepochs = v(end);
Thank you.
Regards,
Maria
>
>
> On Tuesday 08,January,2013 01:45 AM, Makoto Miyakoshi wrote:
>> Dear James,
>>
>> Ah, that makes sense.
>>
>> Makoto
>>
>> 2013/1/7 James Desjardins <jdesjardins at brocku.ca
>> <mailto:jdesjardins at brocku.ca>>
>>
>> Hi Maria,
>>
>> I just came across a bug in the eegplot function that may account
>> for the shifted rejection boundaries you reported finding while
>> scrolling through your continuous data.
>>
>> If the paging buttons { [ << ] or [ >> ]} are quickly clicked
>> twice it can happen that the signals will advance two windows,
>> while the events will only advance 1 window (e.g. if you are
>> displaying 50 seconds at a time and the current window starts at
>> 100 seconds... then you double click [ >> ] quickly, the figure
>> will display the signals from 200 to 250 seconds but the events
>> that will be superimposed are the events for the time period of
>> 150 to 200 seconds).
>>
>> This is a relatively harmless bug as it is only display... any
>> further interaction with the GUI (including selecting time for
>> rejection) refreshes the figure and the offset is corrected.
>>
>> Let me know if this could account for all of the symptoms that
>> you found while scrolling your continuous data.
>>
>> I have reported this in EEGLab bugzilla (#1393) and will look
>> into solving the issue over the next few days.
>>
>> James
>> ------------------------------------------------------------------------
>>
>> On 18 Nov 2012, at 20:07, Maria Teresa Wijaya wrote:
>>
>>> Dear Makoto,
>>>
>>> I recorded my data using Biosemi Active two system with 64
>>> electrodes at
>>> 256Hz. Data were band pass filtered at 0.1-20 Hz and re-referenced
>>> offline first to nose reference to remove bad channels. Removed
>>> channels
>>> were interpolated and the data were re-referenced to average
>>> reference.
>>> I then checked the continuous data for non-typical artifacts,
>>> removed
>>> them, and saved the data with a new name. The shifted rejection
>>> boundaries problem appeared in this new data set.
>>>
>>> Kindly let me know if I need to provide any other information.
>>>
>>> Thank you.
>>>
>>> Regards,
>>> Maria
>>>
>>>
>>>
>>> On Saturday 17,November,2012 01:33 PM, Makoto Miyakoshi wrote:
>>>> Dear Maria,
>>>>
>>>> We need more information to identify what caused this.
>>>> Could you tell me more detail?
>>>>
>>>> Makoto
>>>>
>>>> 2012/11/12 Maria Teresa Wijaya<a0089301 at nus.edu.sg
>>>> <mailto:a0089301 at nus.edu.sg>>:
>>>>
>>>>> Dear list,
>>>>>
>>>>> I did rejection on continuous data and noticed that the rejection
>>>>> boundaries shifted from where they are supposed to be (picture
>>>>> here:
>>>>> http://www.flickr.com/photos/89964745@N02/8178303896/in/photostream).
>>>>> This happened to several of my subjects, and it also happened
>>>>> to someone
>>>>> else in our lab before. My questions are:
>>>>>
>>>>> - What are the possible reasons of this shift?
>>>>> - Is there any way I can know if any of my event triggers have
>>>>> also been
>>>>> shifted or if only the rejection boundaries are shifted?
>>>>>
>>>>> Thank you for your help.
>>>>>
>>>>> Regards,
>>>>> Maria
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>>>>
>>>>
>>>>
>>>
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>>
>>
>>
>>
>> --
>> Makoto Miyakoshi
>> JSPS Postdoctral Fellow for Research Abroad
>> Swartz Center for Computational Neuroscience
>> Institute for Neural Computation, University of California San Diego
>
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