Re: EEG averaging across subjects

[Friedrich Vogt <Friedrich.Vogt@SBG.AC.AT>]

At 10:53 23.05.00 -0500, you wrote:
>Hi all,
>
>I am trying to find a way to normalize the EEG data I acquired with
>different subjects on the same experimental conditions.
>What are the most reliable methods known to avoid intoducing artifacts?
>
>Thanks,
>
>Virginie
>


Hi Virginie

sorry for not answering Your question untill now. In our  normalization
prozeeding we used online recordings. The epochs were not triggered by an
event
or stimulation. The question was power in a frequency window of interest.
So I don't know, if power is a relevant value in interpreting
ERPs. But what You mean with "artefacts created by the ERP latency disparities
across subjects? Isn't ERP latency a functional meaning by itself? And if so,
wouldnīt it better to leave it that way (;that means don't transform it into a
percent value or so). My meaning is, any normalization (or transformatin)
should
be related to  an functional legitimation. Our normalization was concerned to
the interindividuell difference in EEG- (also ERP) power due to the sculp
thickness. Keep raw data as long as possible and find a plausible reason, why
transforming data. I donīt find a reason to normalize ERP latency. Perhaps
I donīt understand the question.

sincerly yours

Friedrich