# [Eeglablist] Plotting ERSPS averaged across several channels

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Tue Nov 18 15:11:32 PST 2014

```Dear Tom,

> Is there a way to do this using the STUDY function?

I don't think so. You need to write code. You should be able to find it in
the archived mail list since I've been giving it several times. But the
bottomline is that you have to do it yourself.

open edit/plot clusters
plot all ersp
press 'ok' to close the window (this updates the STUDY in the workspace)
click STUDY-cluster(1,3)-icaersp
where you should find {3,3} since you have 3x3 design. Figure out carefully
which one is which (refer to STUDY.design). You should also find something
like erspfreq and ersptime with which you can plot the values. Use
imagesc() and axis xy option.

If you don't understand what to do, let me know.

Makoto

On Mon, Nov 17, 2014 at 11:25 AM, Tom Bullock <thomas.bullock at psych.ucsb.edu
> wrote:

> Hello,
>
> I'm currently working with a STUDY with three groups and three conditions.
> I'm using the std_erspplot function to plot ERSPs.. When I input a single
> channel into std_erspplot, I get a 3x3 grid of ERSP plots, one plot for
> each channel and group e.g.
>
> [STUDY erspdata ersptimes erspfreqs pgroup pcond pinter] =
> std_erspplot(STUDY,ALLEEG,'channels',{'Oz'});
>
> I'd like to plot a separate ERSP for each condition and group, but with
> several channels averaged together (e.g. Oz, O1, O2, PO3, PO4) rather than
> just a single channel at a time.  However, when I select several channels,
> I get one ERSP plot for each individual electrode, averaged over all groups
> and conditions e.g.
>
> [STUDY erspdata ersptimes erspfreqs pgroup pcond pinter] =
> std_erspplot(STUDY,ALLEEG,'channels',{'Oz' 'O1' 'O2' 'PO3' 'PO4'});
>
> I've been through the documentation and cannot see a way to specify
> averaging across channels rather than across groups/conditions.  Is there a
> way to do this using the STUDY function?  One workaround migh be to create
> an averaged "channel" in my epoched dataset (e.g. channel 33 = mean(Oz, O1,
> O3,PO3, PO4)), recompute the ERSPS, and then plot that averaged "channel".
> But before I do that, I just wanted to check if there's an faster, more
> flexible solution?
>
> Any advice would be much appreciated.
>
> Thanks!
>
> Tom
>
> --
> Tom Bullock, PhD
>
> https://labs.psych.ucsb.edu/giesbrecht/barry/Attention_
> Lab/Tom_Bullock.html
>
> Postdoctoral Researcher, Department of Psychological and Brain Sciences,
> University of California, Santa Barbara, CA 93106-9660
>
> bullock at psych.ucsb.edu
>
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--
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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