[Eeglablist] Time-frequency analysis of raw EEG power

[Senne Braem]

Dear Experts,

 

I'm quite new to the time-frequency analysis in EEGLAB (and time-frequency
analysis in general). I would like to take a look at raw EEG power, using
FFT at the Pz in 5 time windows in between 256ms before till 1024ms after
the time locked event. I wanted 4Hz frequency bands in between 2Hz and 38Hz.
In order to do so I used the following command:

 

pop_newtimef(EEG, 1, 45, [-381   1149], [0], 'timesout', [5], 'freqs', [2
38], 'nfreqs', 9, 'baseline', NaN, 'plotitc', 'off');

 

Please note the outcome: http://i.imgur.com/7t89n.png

 

Besides the general question if I'm using the appropriate commands I was
also wondering if I was right in worrying that the power values are still
compared to a certain baseline, since most microvolt values are negative?

 

(minor question) Also, I was wondering how to calculate power values for
non-overlapping time windows, since I assume the time windows now use 125ms
extra information at each side. Would it help if I apply another windowing
method than Hanning windowing, or is this not possible?

 

Thanks in advance,

 

Best,

 

Senne

 

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