[Eeglablist] time-frequency of cluster of ICs

Scott Makeig smakeig at gmail.com
Sun Feb 21 15:17:18 PST 2010

Diego -

Time/frequency analysis as implemented in EEGLAB is relative event-related
dB change in spectral power from baseline (ERSP) and (absolute) inter-trial
coherence (ITC). It thus can operate on the IC time courses themselves
(e.g., the unitless activations). For IC clusters, the grand mean ERSP and
ITC values are used as representative.

An IC activation times a particular IC channel weight gives the
back-projection of the IC to that channel. One could compute e.g. an
absolute power spectrum (uV^2/Hz) there -- At every scalp channel the
projected IC spectrum is the same except for a scalp map weight constant.

Scott Makeig

On Thu, Feb 18, 2010 at 4:13 AM, Diego Lozano Soldevilla <dlozano at ub.edu>wrote:

> Dear all,
> I'm doing an independent component clustering of a 15 participants in 2
> conditions. I've obtained 5 clusters and I wish to do a time-frequency
> analysis of each cluster. I've selected the W matrix of each component of
> each cluster and I've applied to longer epochs to do the time-frequency. My
> doubt consists in what electrode/s I should select to do the time-frequency
> that represent better the source of each cluster: the most activate
> electrode in the mean of the topography cluster for example? Do a PCA of xdimensions of the electrodes?
> Thank you all for your replies in advance.
> Diego Lozano-Soldevilla
> --
> Neurodynamics Laboratory
> Dept. Psychiatry and Clinical Psychobiology
> Faculty of Psychology
> University of Barcelona
> Passeig Vall d'Hebron, 171,
> 08035 Barcelona - Spain.
> Tf: +34 934024493
> Fax: +34 934021584
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Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0961, http://sccn.ucsd.edu/~scott
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