[Eeglablist] EEG Alpha Asymmetry

[Arnaud Delorme]

Dear Gregor,

first you need to compute alpha power. To do so may use the function 
spectopo or newtimef to compute the alpha power. For example for a 
single channel on the left and on the right.

x = 10; % example of channel index on the left
y = 11; % example of channel index on the right
[ spec_x freqs ] = spectopo(EEG.data(x,:), EEG.pnts, EEG.frames, 'plot', 
'off');
[ spec_y freqs ] = spectopo(EEG.data(y,:), EEG.pnts, EEG.frames, 'plot', 
'off');
[tmp alpha_ind] = min( abs(freqs-10)); % find closest frequency to alpha 
at 10 Hz
asymmetry = spec_x(alpha_ind) - spec_y(alpha_ind) % I think asymmetry is 
about subtracting power but I might be wrong.

Hope this helps.
Best regards,

Arno

gkohls at ukaachen.de wrote:
> Dear all,
>
> I collected resting EEG to analyze frontal Alpha asymmetry. Can anyone 
> help me how to analyze alpha band and asymmetries with EEGlab? I tried 
> but did not succeed.
>
> Many thanks in advance,
> Gregor