[Eeglablist] plotting average timewindows with pop topoplot

Arnaud Delorme arno at salk.edu
Thu Jul 28 16:39:46 PDT 2005

Dear Zara,

to plot an average of data points within a particular time range, you 
have to do it from the command line. For performing this operation on 
your current dataset, use the following code

range = [0 50]; % range in ms
pts = round(eeg_lat2point(range/1000, [1 1], EEG.srate, [EEG.xmin 
EEG.xmax])); % convert latencies in seconds to data points
ERP = mean(EEG.data,3); % average all data trials
ERPinrange = mean(ERP(:, pts(1):pts(2)),2); % average data points in 
specified time range

figure; topoplot(ERPinrange, EEG.chanlocs); % plot average scalp map


ps001zmb at gold.ac.uk wrote:

> Hi there,
> I have a question regarding the scalp latencies that are plotted using 
> the pop topoplot function in EEG Lab. As far as I understand, the 
> function plots a scalp distribution at the particular latency you 
> specify as a 'snapshot' of activity at that particular data point in 
> time.
> What I want to do instead is to plot an average of data points within 
> a particular time range - for example plot the average activity 
> between 0-50 ms, 51-100 ms, 101-150 ms etc. Is there an easy way of 
> doing this using the pop topoplot function rather than having to 
> average the data points before importing the data files into EEGLab?
> Thanks very much for your help!
> Zara Bergstrom
> MPhil/PhD student
> Goldsmiths College,
> University of London
> _______________________________________________

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