[Eeglablist] extracting single-trial values

Bastien Boutonnet bastien.b1 at gmail.com
Fri Mar 7 07:37:49 PST 2014

Yeah doesn't seem like there are any built-in functions.

Your suggestion helps a bit. However I need to extract the peak from each epoch. So I guess I have to loop over it. 

What does the squeeze() do. I looked on the matlab help but the explanation is not helpful to me at all. 

Bastien Boutonnet, Ph.D.
Department of Psychology
University of Wisonsin, Madison

Sent from my iPhone, apologies for thumb-induced typos.

On Thu, Mar 6, 2014 at 11:27 PM, Stephen Politzer-Ahles
<politzerahless at gmail.com> wrote:

> Hello Bastien,
> I don't know about built-in functions for this, but if there isn't
> one, extracting them with MATLAB is fairly straightforward anyway. For
> each participant you can run something like this:
> baseline = 200; % length of pre-stimulus baseline in ms, assuming 1000
> Hz sampling rate
> window = [300 500]; % let's say you want to extract the mean from 300-500 ms
> values = EEG.data(:, (window(1)+baseline+1):(window(2)+baseline+1),
> :); % pull out the time window
> values = squeeze( mean( values, 2 ) ); % average over samples
> Then you have a vector consisting of the mean amplitudes for each trial.
> Best,
> Steve
> Stephen Politzer-Ahles
> New York University, Abu Dhabi
> Neuroscience of Language Lab
> http://www.nyu.edu/projects/politzer-ahles/
> On Wed, Mar 5, 2014 at 10:36 AM, Bastien Boutonnet <bastien.b1 at gmail.com> wrote:
>> Dear all,
>> It will be my first attempt to look at ERPs in terms of single-trials. In
>> the first instance I was wondering if anyone had a suggestion regarding the
>> following:
>> I would like to extract a time point (or rather a mean of close time points)
>> for each trial, which I wish to correlate/regress with a continuous
>> variable. I tried to look if there was a function already doing that kind of
>> thing but I was out of luck. 1. Was my search badly done and there IS in
>> fact a function? 2. My search was done correctly, there is no ready-made
>> function and I will have to “manually” extract the information. If so, what
>> could I do? Has anyone done something slightly similar?
>> Thanks in advance for your time.
>> Bastien
>>>> Bastien Boutonnet, Ph. D.
>> Department of Psychology
>> University of Wisconsin, Madison
>> bastienboutonnet.com
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