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Re: EEG averaging across subjects
- To: Multiple recipients of list CLIN_NEUROPHYSIOL <CLIN_NEUROPHYSIOL@LISTSERV.UMU.SE>
- Subject: Re: EEG averaging across subjects
- From: Jerry Larson <jerry@NEUROMON.COM>
- Date: Fri, 2 Jun 2000 23:04:00 -0700
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>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?
Well, sure latency is meaningful on its own, but with ERP's you can
have a wide normal variability of latency, and if you were to compare
the peak amplitude of P300, say, you have to compare the peak, not
amplitude at 300 ms. I used to do clinical EEG and evoked potential
brain mapping, using several different systems, and I remember one
particular system, the BEAM, the only abnormality would always be on
the visual evoked potential-- because the system compared the
patient's amplitude at 100ms to the database. Someone whose P100 was
actually at 95ms, with a perfectly normal VEP, would nevertheless
have a markedly "reduced" amplitude at 100ms, because that was well
downslope from the peak.
>.. My meaning is, any normalization (or transformatin)
>be related to an functional legitimation.
Jerry Larson, MA, CNIM, etc.