[Eeglablist] Can I do ERSP for epochs of 1.25 sec duration?

[arno]

Dear Eric,

yes you can do ERSP. The only problem is that if you want to look a low 
frequencies (1-10 Hz) you need to use epoch lengths which are relatively 
long (3 seconds). With frequent events, it means that time-frequency 
windows may overlap over several experimental events at very low 
frequencies. For high frequencies, frequent events is not a problem at 
all. In your case, I would still use 3-second epochs (-1 to +2 seconds) 
while keeping in mind that several experimental events may influence low 
frequencies activations (baseline may still be set to -0.25 to 0 even in 
this case).

About ICA, you can of course perform ICA on your data. ICA will not help 
in the ERSP problem above though.

Hope this helps,

Arno

Eric Landsness wrote:
> If my experimental events occur frequently (every 1.25 seconds) can I legitimately do ERSP time/frequency analysis?
>
> Background: A subject is repeatedly (90 trials) primed to perform a motor movement every 1.25 sec, where the movement takes about 750 msec to complete.  I realize that typically we use -1s to +2s for time/freq analysis because event-related changes in the EEG need time to develop and to recover.  In this situation can I get away with using -0.25s to 0 for my baseline and 0 to +1s for my post-event activity?
>
> If the eeglablist feels that I can’t do ERSP, I can still perform ICA, correct?  The ideal situation would be to perform ICA and then feed the independent components into timef.
>
> Thank you,
> Eric 
> PhD student
>
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