[Eeglablist] How to calculate EEG asymmetry index?

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Thu Jan 26 13:31:56 PST 2017

Dear Frederic,

You need to code. See the following page for the example.
https://sccn.ucsd.edu/wiki/Makoto%27s_useful_EEGLAB_code#How_to_extract_EEG_power_of_frequency_bands

> I then calculate asymmetry log(absolute power F4)-log(absolute power F3)
to calculate the index, or even using a mean of absolute power for groups
of electrodes. Do you think that is the right?

Yes, that makes sense. See the example code and you can do it.

> Does the calculation of asymmetry index requires the use of absolute
power?

No I don't think so. Using dB makes the data easier to handle.

Makoto

On Tue, Jan 24, 2017 at 6:54 AM, Frederic Andre Albert Haesebaert <
frederic-andre-albert.haesebaert.1 at ulaval.ca> wrote:

> Hi all. In order to compute EEG asymmetry on resting state datasets I use
> the EEGlab toolbox spectopo function, so I get the spectra in dB for each
> frequency, then I calculate absolute power (with the formula
> 10^10(spetra)/10) and a mean of this absolute power for each electrode in
> the alpha band. I then calculate asymmetry log(absolute power
> F4)-log(absolute power F3) to calculate the index, or even using a mean of
> absolute power for groups of electrodes. Do you think that is the right?
> Does the calculation of asymmetry index requires the use of absolute power?
>
>
> Regards
>
>
>
>
>
> *Frédéric Haesebaert, MD, PhD*
>
> *Post-Doctorant (Post Doctoral Fellow), Université Laval (Laval
>
> *frederic-andre-albert.haesebaert.1 at ulaval.ca
> <frederic-andre-albert.haesebaert.1 at ulaval.ca>*
>
> *418-663-5000 <(418)%20663-5000> (poste 4772)*
>
>
>
>
>
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--
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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