[Eeglablist] scale for component averages plots

[Arnaud Delorme]

Hi Makoto and Mirek,

component activities are scale to RMS (root mean square) of their projections on all data channels. So the unit of their activity is the same as the data channels (microvolt). 
Hope this makes sense,

Arno

On 11 Oct 2012, at 15:42, Makoto Miyakoshi wrote:

> Dear Scott and Mirek,
> 
> My understanding is that the unit, microV, can be used because ICA
> does not do any rescaling. However, real source activity must be much
> larger than microV scale. So something must be wrong in my
> understanding. Please tell me where I'm making a mistake.
> 
> Also, I found the EEGLAB option has 'Scale ICA activities to RMS'...
> what does this do? Default is on.
> 
> Makoto
> 
> 
> 2012/10/11 mirek <3mirek at gmail.com>:
>> Hi All,
>> 
>> After ICA decomposition and ICs clustering there's a possibility to plot
>> the ERPs of the clusters ('Plot component measures'). The plots have µV
>> on the vertical axis, but I wonder what, in fact, µV mean in this
>> context? For usual channel ERP averages we have just averaged voltage
>> measured by particular electrode. In case of clusters, the plots show
>> only reconstructed averaged activity of the deep cluster centroid. So
>> how can I treat these units? As a relative rather than real ones?
>> 
>> Mirek Wyczesany
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> 
> 
> 
> -- 
> Makoto Miyakoshi
> JSPS Postdoctral Fellow for Research Abroad
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
> 
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