[Eeglablist] Creating ERPs contralateral and ipsilateral to stimulus presentation

[Stephen Politzer-Ahles]

Dani,

I don't know of an easy way to do this within EEGLAB, but after doing your
preprocessing it should be easy to do in MATLAB. Assuming you have the data
coded for separate conditions (i.e., with one condition for left-field
color change and another condition for right-field color change), you could
just make ERPs for each condition, and then create a "contralateral" ERP by
averaging the data from the left electrodes in the right-field condition
with the data from the corresponding right electrodes in the left-field
condition; likewise you could create the "ipsilateral" ERP by averaging
data from the left electrodes in the left-field condition with the data
from the corresponding right electrodes in the right-field condition. I
don't know enough about your research area to know if this is conceptually
OK to do, but at least from the technical standpoint it would be easy to
implement.

Best,
Steve

On Sun, Jan 29, 2012 at 2:55 PM, Daniela Gledhill
<d.gledhill at uni-bremen.de>wrote:

> **
> Dear all,
>
> I am doing my PhD in Visual Neuroscience and quite recently started my EEG
> analysis with EEGLAB.
> In my experiment two stimuli are presented bilaterally with one of them
> changing it's color. I am trying to create ERPs contra- and ipsilateral to
> the color change, but not sure how to proceed in EEGLAB.
>
> There is only one message in the discussion list with the idea of "Swap
> the data, not the channels. Leave the channels alone."
> But how does it work?
> - contralateral:  data of left-hemispheric electrodes for changes on the
> right side and data of right-hemispheric electrodes for changes on the left
> side
> - ipsilateral:  data of left-hemispheric electrodes for changes on the
> left side and data of right hemispheric electrodes for changes on the right
> side
>
> It would be wonderful to get some help with that!
>
> Kind regards from Bremen,
> Dani
>
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-- 
Stephen Politzer-Ahles
University of Kansas
Linguistics Department
http://www.linguistics.ku.edu/
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