[Eeglablist] How to compute the CDA in EEGLAB (contralateral delay activity)

[Massimiliano Papera]

Dear All,



I am investigating the relationship between Attention and Memory and would
like to use the Contralateral Delay Activity (CDA) as a correlate of the
visual working memory. I am dealing with the bin operations function.

I would like to check through the Discussion list if anyone who is familiar
with the CDA knows I am using the right coding to get my CDA component
across three different conditions.

I am investigating 3 different pair of electrodes (p3-4, o1-2 and p7-8) for
correct and incorrect responses. However I am not sure if I need to filter
out the incorrect trials.



Thank you

ERP = pop_binoperator( ERP, {'LH = [18 23 24]' 'RH = [14 28 27]' 'nb1=
b1 at RH-b1@LH label CDA LVF20' 'nb2= b2 at LH-b2@RH label CDA RVF20' 'nb3=
b3 at RH-b3@LH label CDA LVF40' 'nb4= b4 at LH-b4@RH label CDA RVF40' 'nb5=
b5 at RH-b5@LH label CDA LVF22' 'nb6= b6 at LH-b6@RH label CDA RVF22'});



This gives me 6 bins, 2 per each of the 3 conditions. Each pair gives me
erp for either left visual field (LVF) or right visual field (RVF).



To get the CDA I now subtract  the activity between left and right visual
field trials for all of the 3 conditions:

ERP = pop_binoperator( ERP, {'nbin1= b1-b2 label CDA 2T0D' 'nbin2=b3-b4
label CDA 4T0D' 'nbin3=b5-b6 label CDA 2T2D' });



This gives me 3 CDA component, one for each condition.



Does anyone know if this is correct to compute the CDA?



Thank you



Thanks to everyone

Massimiliano Papera
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