[Eeglablist] How to do TF analysis with eeglab

[Arnaud Delorme]

>I want to do time-frequency analysis with eeglab. My data is 3-minute-long steady state visual evoked potential. I have trouble with doing time-frequency anaylsis with eeglab. The message is "Epochs must be extracted before running the function". Only one epoch for my data. The time-frequency analysis can not be used for one- epoch  data? How can I do?
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You may use the specgram function of the Matlab signal processing
toolbox. For instance,
figure;specgram(EEG.data(1,:), 512, EEG.srate, 256);

To respond to the question of Pradyumna S Upadrashta about the
difference between timef and specgram, specgram computes the spectrogram
(continuous time-frequency decomposition) and timef() compute the
average spectrogram of a collection of epochs (and optionally subtract
the baseline activity). The equation timef uses is described in the
EEGLAB paper (J Neuroscience methods).

In a future version of EEGLAB, we will allow timef() to plot the
spectrogram too (and assess significant changes).

Best

Arno

-- 

*Arnaud Delorme, Ph.D.*
Computational Neurobiology Lab, Salk Institute
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