[Eeglablist] Time-frequency analysis (subtraction first or analysis first)

[Thomas Ferree]

Speaking for myself, we do not subtract off the ERP, so we must acknowledge
that our TF results have both 'evoked' and 'induced' activity.The ITC
measure in EEGLAB can help with interpretation, by showing the
degree of phase similarity across trials at each frequency and time.

Isolating the induced activity by subtracting the ERP first is a worthwhile
goal, but it is technically complicated due to inter-trial variability of
the ERP.
Some work has been done on this topic.  Truccolo et al (2002), for example.

On Tue, Apr 15, 2008 at 3:41 PM, Stanley Klein <dualitystan at gmail.com>
wrote:

>
> Andrei, I'm not sure I understood your last comment or question, but I
> have a related question. Whenever one does time-frequency power plots I
> would think that one should ALWAYS first get the time locked average and
> subtract it off  of all the individual trials. Then one could do a TF plot
> of each. How many on this list do that?  I suspect that people mix together
> the standard evoked response and also the phase varying response. Why do
> that since its so easy to show the the two TF plots separately.
>
>
-- 
Thomas Ferree, PhD
Department of Radiology
UT Southwestern Medical Center
Email: tom.ferree at gmail.com
Voice: (214) 648-9767
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