[Eeglablist] Question about sorting epochs

[Renzo Lanfranco]

Hi Arno,

Thanks for the reply! About the second part of your answer, the problem is
that these stimuli are applied in series (to induce an illusion), so the
baseline of each of those epochs is contaminated by the stimulus applied
before. Therefore, I want to use those 2 seconds of wait at the beginning
of the trial as the baseline for each stimulus event. Each trial has 2
seconds of no stimulus, then a series of 5 stimuli. Epoched, it would be
one segment of 2 s and five segments of 1 s each (the stimulus' of the
event is at time zero there). Then copy the 2-s-long segment and paste it
at the beginning of each stimulus segment, so we end up with five 3-s-long
epochs. I wonder if anyone has a script for this.

Best,
Renzo

--




On Tue, 4 Apr 2023 at 07:59, Arnaud Delorme via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> > I was wondering if you could help me with something. I have EEG datasets
> > that need an unconventional treatment before analysis. In this
> experiment,
> > participants hear a beep (event 1), and 2 seconds later, a series of 5
> > stimuli are shown, with 1 second of separation in between (events from 2
> to
> > 6). After pre-processing and epoching, epochs with event label 1 are 2000
> > ms long (from 0 to 2000 ms, no stimulus) and the other epochs are 1000 ms
> > long (from -500 to +500 ms, where time zero indicates stimulus
> > presentation).
> >
> > How can I average across all the epochs with event label 1, 2, 3, 4, 5,
> and
> > 6
>
> This is best done by creating an EEGLAB study (which can be created with 1
> participant only).
> Then you can compare epochs 1, 2, 3, 4, 5 and 6.
>
> > and then copy the epochs with event label 1 to every other epoch so the
> > resulting epochs are 2000 ms (duration of epoch 1) + 1000 ms (duration of
> > each stimulus epoch)? Thus, we’d have resulting epochs of -2000 ms to
> +1000
> > ms. The objective is to use the epoch with event number 1 as baseline for
> > the stimulus-related epochs (event numbers 2, 3, 4, 5, and 6).
>
> This would require a script.
> It is unclear what you are trying to do. If it is a standard ERP baseline,
> you can extract very long epochs with events 1, 2, 3, 4, 5, and 6 compute
> the baseline, then extract smaller epochs.
>
> Cheers,
>
> Arno
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu