[Eeglablist] using BCILAB to deploy different approaches on BCI competition dataset

Thu Sep 29 02:07:55 PDT 2011

Thanks for the reply, using the points in
this<http://sccn.ucsd.edu/wiki/A02:_Importing_Event_Epoch_Info>page,
there is a little description about event types:

...the channel is an event channel with values 1 (stimulus onset), 2
> (subject response), and 0 (other)....
>
I'm not really sure what these are. is 1 , 2 or 0 just a naming convention?
so they could be anything as long as they are consistently named through the
whole process using EEGLAB and BCILAB? from what I've figured out in
this<http://sccn.ucsd.edu/wiki/A02:_Importing_Event_Epoch_Info>page ,
for each "time X channel" entry there should be an event type.now I
have no idea what kind of event it would be for each of entries in my
dataset? 1,2 or 0?
Another question is about latencies, how can I obtain latencies for my
events?
-----------
Regards, Mehdi Karamnejad
Rajaee Artificial Intelligence & Robotics Laboratory  , Shahid Rajee
University

On Fri, Jun 17, 2011 at 12:50 AM, Christian Kothe <
christiankothe at googlemail.com> wrote:

> Hello Mehdi,
>
> yes, importing the format of the BCI competition into an EEGLAB-compatible
> format with appropriate markers requires quite some special treatment. On
> our wiki we have a piece of code which demonstrates loading & running a
> simple CSP approach over it using just bare-bones MATLAB:
> http://sccn.ucsd.edu/wiki/Minimalist_BCI This should give you an idea of
> how the data is laid out (this is for the .mat version of one of the data
> sets - I hope it's the data set that you are interested in). You may also
> check whether this code runs for you right out of the box.
>
> To generate from this an EEGLAB-compatible data set, you might want to take
> a look at the wiki page on the data structure layout:
> http://sccn.ucsd.edu/wiki/A05:_Data_Structures. A bit more conveniently is
> BCILAB's function set_new, which is used like in the following usage
> example:
>
> If you have extracted the following variables from the BCI competition data
> set:
> mydata (numeric array of #channels x #samples)
> mysrate (sampling rate in Hz)
> mychannels (cell array of channel names, e.g. {'C3', 'C4', 'Cz', ...})
> myeventtypes (cell array of event type strings -- note: these should be
> strings, e.g. {'1', '2', '1', '2' ...}, not numbers)
> myeventlatencies (cell array of event latencies, measured in samples, e.g.
> {10200, 20300, 55100, ...})
>
> Then you can create a new set using the command.
> traindata = exp_eval(set_new('data',mydata, 'srate',mysrate,
> 'chanlocs',struct('labels',mychannels),
> 'event',struct('type',myeventtypes,'latency',myeventlatencies)));
>
> If you save the data set now as a .set file using
>
> pop_saveset(traindata)
>
> ... then you can then use it with BCILAB following the GUI tutorials. For
> this to work, you need to remember that you named your event types a certain
> way when you created the EEGLAB set, and BCILAB needs to know what events it
> should use. The tutorial data sets use different event types than those that
> you have, so assuming that you used the strings '1' and '2', you need to
> pass {'1','2'} instead of the {'S  1', 'S  2'} in the GUI dialog box where
> the marker names are specified.
>
>
> Likewise, when you want to go through the scripting tutorials with it (say:
> tutorial_erd1.m or tutorial_erd2.m), you first need to replace the
> respective io_loadset line which loads the file (you can also directly use
> the traindata that you have in your workspace),
> and replace the names of the event types that are declared to BCILAB. In
> tutorial_erd1.m, for example, the line
>
> myapproach = {'CSP' 'SignalProcessing',{'EpochExtraction',{'TimeWindow',[0
> 3.5],'EventTypes',{'StimulusCode_2','StimulusCode_3'}}}};
>
> needs to be changed to
>
> myapproach = {'CSP' 'SignalProcessing',{'EpochExtraction',{'TimeWindow',[0
> 3.5],'EventTypes',{'1','2'}}}};
>
> ... and you should be ready to go (again assuming that you actually named
> your markers '1' and '2'). If you want to use the more advanced approaches,
> you need to adapt the event types there, too.
>
> Best,
> Christian
>
> PS: I'm actually planning to write a tutorial for BCI competition data sets
> at some point, but didn't yet get to it.
>
> 2011/6/16 Mehdi Karamnejad <mehdi.karamnejad at srttu.edu>
>
>> Hello,
>>
>> I'm trying to deploy some approaches of BCILAB on BCI competition IV
>> dataset  1 (here <http://www.bbci.de/competition/iv/desc_1.html> is the
>> link to description of this dataset)
>> I take the following steps:
>>
>>    1. cnt matrix  contains raw continues EEG data in volts and I first
>>    convert the values to micro volts . cnt matrix also arranges data in
>>    the form of  time x channels so I take the transpose of the matrix to
>>    produce a matrix in the form of channels x time
>>    2. for testing reasons and making processes much less time-consuming ,
>>    I just extracted a small portion of the signal to import into EEGLAB
>>    3. then I imported the extracted signal into EEGLAB  along with it's
>>    channel location
>>    4. then I had to create the  Events because BCILAB needs it, I did
>>    this using  File>> Import event info >> >From data channel  and picked 59 as
>>    my event channel and left other options as default since I'm not sure what
>>    they do yet.
>>    ** 59 is the number of entire channels . I'm not sure what my events
>>    are although I've read the EEGLAB wiki, *could someone tell me what
>>    are experimental events in EEG signals? and how can I figure out which
>>    channel(s) are the event channels?
>>    *
>>    5. then I saved all of my work as an EEGLAB dataset and loaded it into
>>    BCILAB and created a new CSP approach. when modifying the approach I don't
>>    know what to fill in for "Epoch time window relative to the events" and
>>    "Event marker types for which epochs shall be extracted " . for the second
>>    one I have read a tutorial which  's 1''s 2' is filled in but I don't
>>    really understand what this means and when I try to train my model I get an
>>    error with these settings.
>>    *could you please explain to me what ** "Event marker types for which
>>    epochs shall be extracted " is?*
>>
>> and could you tell me what do I generally need  to do to make my dataset
>> appropriate for loading into BCILAB? (for now appropriate enough to use the
>> CSP approach )
>> -----------
>> Regards, Mehdi Karamnejad
>> Rajaee Artificial Intelligence & Robotics Laboratory  , Shahid Rajee
>> University
>>
>>
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