[Eeglablist] help with power spectral density

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Sun Nov 16 13:54:42 PST 2014

Dear Omar,

Sorry for slow response.
You have to use the spectopo() function in the command line to obtain the
raw values. There were related posts in the past in which I have been
repeatedly showing the following. Hope it helps.

% for your epoched data, channel 2
[spectra,freqs] = spectopo(EEG.data(2,:,:), 0, EEG.srate);

% delta=1-4, theta=4-8, alpha=8-13, beta=13-30, gamma=30-80
deltaIdx = find(freqs>1 & freqs<4);
thetaIdx = find(freqs>4 & freqs<8);
alphaIdx = find(freqs>8 & freqs<13);
betaIdx  = find(freqs>13 & freqs<30);
gammaIdx = find(freqs>30 & freqs<80);

% compute absolute power
deltaPower = 10^(mean(spectra(deltaIdx))/10);
thetaPower = 10^(mean(spectra(thetaIdx))/10);
alphaPower = 10^(mean(spectra(alphaIdx))/10);
betaPower  = 10^(mean(spectra(betaIdx))/10);
gammaPower = 10^(mean(spectra(gammaIdx))/10);

If you don't want to code, maybe you want to try the following toolbox.


On Mon, Nov 3, 2014 at 12:24 PM, Omar Ortega <tourette95 at gmail.com> wrote:

> Hi there!
> I have a question about computing psd,
> I loaded an neuroscan .ee file and I wan to compute the power spectral
> density, I saw in webpage that is possible to do that by using the plot
> function, the problemm is:
> I clicked on plot function, but how can i get that into numerical data?
> I need to export the psd in text file in order to work whit it, so first i
> hope using plot function from eeglab was enough to get the psd.
> help please!!!
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Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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