[Eeglablist] re-epoching, ICA selected periods

José Luis joseluisulloafulgeri at gmail.com
Sat Mar 4 13:54:15 PST 2017


Hi Tarik,

Thanks for the input,
Looks the approach we are taking is good,
However, I haven't be able to epoch using two triggers, I need to select an
epoch which is 0.5 sec before a trigger A, and 0.5 sec after a trigger D,
is there any way to do this?,

thanks for your help,
best
Jose

On 3 March 2017 at 21:25, Tarik S Bel-Bahar <tarikbelbahar at gmail.com> wrote:

> Hello Jose,
>
> Yes you should be able to re-epoch, then run ICA on just the epochs
> without the buffer time,
> and then re-apply the ICA results to the files with the buffer time, and
> go from there.
> You may have to insert a new trigger, but you should be able to just
> "select an epoch start/end time that does include the buffer times. First
> try it with one file from the gui, and use eegh to build a script for that.
>
> Overall, if your buffer time is under ~2 seconds, and has no large
> artifacts, it would be okay to include them in the ICA. In other words,
> your ICA results should look very similar with either method (with or
> without the buffer periods).
>
> Check Makoto's general recommendations for ICA just in case, if you
> haven't had a chance to.
>
> On Fri, Mar 3, 2017 at 10:11 AM, José Luis <joseluisulloafulgeri at gmail.com
> > wrote:
>
>> hi,
>>
>> I'm analysing EEG data and want to perform ERP and time-frequency
>> analyses,
>> I'm doing the pre-processing with EEGlab,
>> I wanted to move fast so I epoch my data and then I proceed with the
>> artefact rejection. I epoch my data taken into consideration that for
>> time-frequency I need a buffer zone,
>> Now, I want to perform ICA but only in a selected time period of
>> interest. I have several question here:
>> 1) Can I do ICA in select periods of time within my epochs?
>> 2) If not, I could try to re-epoch my dataset, perform ICA in the
>> re-epoched (shorter) dataset, and then re-inject the weight of the ICA back
>> to the original dataset), does that sound ok? I'm only interested in my
>> selected time period of interest, and the rest of the signal I would use it
>> because I need a buffer zone, and because long periods to compute power at
>> low frequencies,
>> 3) Can I epoch relative to two triggers, i.e. for a sequence of triggers:
>> A, B, C, D, E I want to do from -0.5 relative to A until E,
>>
>> Thanks in advance for your help,
>> Jose
>>
>> --
>> José Luis ULLOA FULGERI, PhD
>> +32477429007 <+32%20477%2042%2090%2007>
>> +32492646477
>> https://sites.google.com/site/joseluisulloafulgeri/
>>
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>


-- 
José Luis ULLOA FULGERI, PhD
+32477429007 <+32%20477%2042%2090%2007>
+32492646477
https://sites.google.com/site/joseluisulloafulgeri/
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