[Eeglablist] Frontal Alpha Asymmeytri Score Problem

robert lawson robert at sherab.net
Sat Feb 20 12:03:54 PST 2021


Alpha asymmetry scores depend upon the reference used. Many of the early
papers used CZ reference. Other studies used different references. I did a
presentation about 25 years ago showing there was low correlation between
linked ear Alpha asymmetry and CZ alpha asymmetry. Soon after I did this
presentation, a guy published papers about this. I can't remember his name
but it shouldn't be too hard to find. Probably these papers were around
2000.

On Sat, Feb 20, 2021, 9:04 AM gökhan alper figen <gokhanalper at gmail.com>
wrote:

> Hi everyone,
> i have phd project. My eeg device is emotiv epoc + 14 channel.
> I applied on EEGLAB for raw egg preprocess:
> 1-remove baseline(for time)
> 2-select channel
> 3-load channel location
> 4-remove epoch baseline(DCOFF)
> 5-1-45 Hz Fır-filter
> 6-???? i dont apply re-reference. Because my device reference is
> Mastoid(P3-P4). But i am not sure for this step. I tried
> re-reference(average), but this time ICA calculate one a component is under
> calculated. HELP ME. Is it necessary to re-reference?
> 7- ICA
> 8-Remove for Artifact applied ADJUST
> 9- Last one on matlab, i applied frontal alpha asymmetry algorithm(8-13Hz).
> But i have got another problem in here. I got AF3-AF4,  F7-F8,  F3-F4,
> FC5-FC6 dipole electrode on frontal lobe. Which dipole is important frontal
> alpha asymmetry? Used one by one at different times in the literature.İn
> addition i have different score same trial(for example: AF3-AF4-->positive,
> F7-F8--> negative,  F3-F4-->positive, FC5-FC6-->negative ). is it possible?
>
> FAA SCORE:
> AF4-AF3 F8-F7 F4-F3 FC6-FC5 MeanFAA
> 0,835219 1,803982 0,768355 1,929266 1,334206
> 1,552542 0,523332 1,283658 0,662677 1,005552
> 0,212559 0,767369 -0,09146 0,533678 0,355537
> 2,695686 0,651778 0,208955 1,1194 1,168955
> 0,021023 0,745326 0,28 1,529339 0,643922
> 0,400539 0,693247 0,435739 1,952571 0,870524
> 0,069624 0,294606 1,358425 0,82884 0,637874
> 0,646927 0,528689 0,728926 1,521723 0,856566
> 0,260962 -0,12185 1,093646 1,173347 0,601527
> 1,228531 1,233191 1,044209 1,793257 1,324797
> 0,020307 0,647727 1,570798 1,414552 0,913346
> -0,58441 0,484781 0,804384 1,398788 0,525887
> 1,199436 1,282988 0,766968 1,721898 1,242822
> -0,2001 -0,69111 0,976038 1,513998 0,399708
> 0,184563 1,183316 1,678075 2,736944 1,445725
> -0,10969 0,93127 0,343262 0,51734 0,420546
> -0,22403 0,445983 -0,2119 0,763368 0,193354
>
> thanks
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