[Eeglablist] How can I apply headplot to time windows?

[Arnaud Delorme]

Hi Niko,

> i have got a question concerning 'headplot'. this function plots field 
> maps for a certain latency, i.e. a single data point. how can i plot 
> an average map, averaged across sampling points, e.g. the average map 
> of the time window from 300 to 500 ms?

% first find out data points corresponding to your latencies of interest
% the easiest way to do that is to use the function "eeg_lat2point"
% 
------------------------------------------------------------------------------------------
tlim = eeg_lat2point( [0.3 0.5], 1, EEG.srate, [EEG.xmin EEG.xmax]);

% alternativelly you may compute it yourself
% note that the +1 at the end is because the first data point has index 
1 and not 0
% ---------------------------------------------------------
tlim(1) = (0.3-EEG.xmin)*EEG.srate+1;
tlim(2) = (0.5-EEG.xmin)*EEG.srate+1;

% then compute the average for this time period
% ------------------------------------------------------------
tlim = round(tlim); % find closest data points
ERP                = mean(EEG.data, 3); % averages over data trials, 
i.e., compute the ERP
ERP300to500 = mean(ERP(:,tlim(1):tlim(2)), 2); % average of time points

% plot the resulting average using headplot
% (assuming you have already computed the splinefile by calling the
%  "Plot > ERP map series > In 3-D" menu item at least once)
% ------------------------------------------------------
figure; headplot(ERP300to500, EEG.splinefile, 'title', 'Average ERP from 
300 to 500 ms');

Arno
-- 

*Arnaud Delorme, Ph.D.*
Swartz Center for Computational Neuroscience, INC, University of San 
Diego California
La Jolla, CA92093-0961, USA

*Tel* :/(+1)-858-458-1927 ext 15/
*Fax* :/(+1)-858-458-1847/
*Web page*: sccn.ucsd.edu/~arno <http://www.sccn.ucsd.edu/%7Earno>
*To think upon*:

    In the process of defining myself, I have a tendency to set up rules
    and boundaries and then forget that rules are made to be broken, as
    are boundaries to be expanded and crossed.

        /Kathleen Casey Theisen/  

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