[Eeglablist] CDA plotting and difference waves

[Javier Lopez-Calderon]

Hi Dwight,

I'll take a look into this. Meanwhile please try the following:

i) Using Bin Operations on your ERPset, create a new one (*) as follows (at bin operations GUI check "Create new ERPset (independent transformations"):

LH  = [1 3 5]
RH  = [2 4 6]
nb1 = 0.5*b1 at RH + 0.5*b2 at LH  label average contra
nb2 = 0.5*b1 at LH + 0.5*b2 at RH  label average ipsi


ii) Once you create this 2-bin ERPset, go back to bin operations again and add a third bin as follows (at bin operations GUI check "Modify existing ERPset (recursive updating"):

b3 =  b1-b2 label average contra minus ipsi


(*) The reason for creating a new ERPset  is that the new one has less channels than the current one, so its data matrix would no longer fit on it.


I hope this helps,


Javier


PS: You may also use erplab at ucdavis.edu for sending questions/feedback



>> From: Dwight Peterson <dwight.peterson23 at gmail.com>
>> Subject: [Eeglablist] CDA plotting and difference waves
>> Date: February 9, 2013 7:27:59 PM PST
>> To: <eeglablist at sccn.ucsd.edu>
>> 
>> 
>> Hello everyone, 
>> 
>>          I am using ERPLAB to try and plot the CDA (difference waveform) from my Contralateral and Ipsilateral waveforms.  In my Bin Operations relative to my erpset,  I have used the following basic formula (modified to my specific bins and channels,  etc):   (as recommended by Dr. Luck in the ERP tutorial)
>> 
>> However, when I go to plot the difference waveforms for my respective electrode pairs and conditions (i.e., bins), I get a plot with axes for each of my electrode pairs, but no difference waveform (or waveform at all for that matter).     Is there something that I perhaps need to install/update to insure proper plotting, etc.?   I've also noticed this when trying to plot a contra and ipsi waveform for an electrode pair, wherein the only wave form that will come up when I plot 1:2, is 2 (but not 1).   Any thoughts as to why this might be?   Thanks!!! 
>> 
>> 
>> LH = [1 3 5]
>> RH = [2 4 6]
>> b1 = (b2 at LH + b1 at RH)/2 label Average Contra
>> b2 = (b1 at LH + b2 at RH/2 label Average Ipsi
>> b3 = ((b2 at LH + b1 at RH)/2) – ((b1 at LH + b2 at RH)/2) label Average Contra Minus Ipsi
>> 
>> --Dwight--
>> 
>> -- 
>> Dwight J. Peterson, M.A.
>> Graduate Assistant
>> Cognitive and Brain Sciences
>> Department of Psychology/296
>> Memory and Brain Laboratory
>> University of Nevada, Reno
>> Reno, NV 89557
>> Cellular: 319-231-8596
>> Laboratory: 775-682-8667







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