[Eeglablist] ICA on continuous data - eye artifact component

[ida miokovic]

Dear Makoto,

Within IC1 I see horizontal line in the lower half of the figure, meaning
this component "is happening" only during one trial (right?), which is
strange to me since everything else about this component (location,
activity power spectrum and plot of the component in time domain) is
showing that it is most likely eye artifact...

In mentioned diagram, I would expect it to be more distributed through
trials and to look more like:
http://sccn.ucsd.edu/wiki/File:I94component3_properties.jpg

One data set of mine consists of one subject performing one task (for
example for 15 secs) than there was a break time (10 secs which I manually
removed from he data set) and than again task performance etc. What is
considered in this case to be a trial? Here I have some continuous data
with markers marking the moments when task is performed and some boundary
markers when unuseful data (break time) was rejected.

All the best

Ida


On Tue, Apr 2, 2013 at 3:27 AM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu>wrote:

> Dear Ida,
>
> >Third mentioned diagram is shown with dimensions: 200 trials and 810 ms
> on y and x axis respectfully (image is in the attachment) - why exactly
> these values are taken? Could I change those?
>
> These are chosen arbitrarily. This plot is called ERPimage, and as you can
> see in its naming, the plot is to show trial-by-trial event-related phase
> and amplitude structure. Since your data are continuous, the function
> determined a good number to chop up your data to make them aligned in the
> box.
>
> If you see a 'column' (or 'slope') in the ERPimage that means there was
> phase-locking event. Do you see it?
>
> Makoto
>
> 2013/3/30 ida miokovic <ida.miokovic at gmail.com>
>
>> Dear list,
>>
>> I run ICA on continuous data and now am interested into removal of the
>> components that represent eye and muscle artifacts (and some other if
>> recognized).
>>  When I go through Tools --> Reject data using ICA --> Reject components
>> by maps there is possibility for me to see Activity power spectrum, 2D
>> location of component presence and time - trials diagram. Third mentioned
>> diagram is shown with dimensions: 200 trials and 810 ms on y and x axis
>> respectfully (image is in the attachment) - why exactly these values are
>> taken? Could I change those?
>>
>>  Since it is IC1 that is shown, I expect it to be most likely an eye
>> artifact, but I am confused about the look of the third diagram - it does
>> not look like eye artifact should  and blinks are not visible as shown in
>> EEGLAB tutorial about ICA. Am I missing somenthing? maybe it is because of
>> only 800 ms of the dataset on x axis?
>>
>> Thanks
>>
>> Ida
>>
>>
>>
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>
>
>
> --
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>
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