[Eeglablist] ICA clustering

[Larry L Greischar]

We've been working with attentional blink task data (64 channel) for 20 
subjects using EEGLAB (version 5.02) and are currently attempting to 
cluster ICA components. There appears to be a wide range of results 
produced depending on the chosen clustering parameters. Some experienced 
advice on the following would be greatly appreciated:

weight and number of pre-clustering parameters

reasonable PCA dimensions for ERP, spectrum, ERSP/ITC

better to reduce the number of parameters used for pre-clustering than use 
final dimension reduction

number of clusters to compute (Should this be based on ERP literature? Is 
it reasonable to have a cluster with several components per subject?)

when using dipoles it appears to be necessary to rather carefully hand 
screen artifact components (EMG components are sometimes modelled by 
dipoles with RV < 10% and "good" components sometimes have relatively large 
RVs ~30%) How much hand screening is necessary for good results?

Thanks in advance,

Larry Greischar
Heleen Slagter
University of Wisconsin