[Eeglablist] How to "difference plot" of coherences from two different datasets or conditions in SIFT and/or EEGLAB
imponderabilion at gmail.com
Wed Feb 12 04:40:34 PST 2014
You can find all computed connectivity measures in EEG.CAT.Conn (although I
am not sure why the field is named 'CAT' - it would be nice to know :) ).
The matrices that reside there have the same names as method names that can
be chosen in SIFT connectivity measures gui.
For example EEG.CAT.Conn.nPDC contains a 4-d matrix of normalized partial
The dimensions are component-component-time-frequency (the last two may be
the other way around, I don't remember now).
(BTW "obliterate the putative "difference coherence" due to destructive
interference." sounds really cool. :) Would make for good lyrics for a SIFT
theme song maybe? )
7 lut 2014 22:32 "James Jones-Rounds" <jj324 at cornell.edu> napisał(a):
> Hello all (and Tim),
> I am a happy SIFT user and have found some exciting results measuring
> event-related complex coherence in certain frequency bands, between
> independent components, in a within-subject design using SIFT. My next step
> is to generate "difference" plots, i.e. the coherence (between two
> components) during one task (i.e. averaged epochs) subtracted from the
> coherence (between those same two components within the dataset, or between
> different components in another dataset) during another task.
> I don't see an apparent way to do this in SIFT. Do you have any
> One idea I had was that if the coherence data existed in a matrix or
> structure field that SIFT generated, I could do a matrix-subtraction and
> then plot that resulting matrix. I wouldn't want to just matrix-subtract
> one set of raw frequency data from another, because I imagine that unless
> they're perfectly phase-locked (unlikely), that would obliterate the
> putative "difference coherence" due to destructive interference. I want to
> just matrix-subtract the coherence values (coherence power at each
> frequency, at each time point in the epochs) that's used to plot coherence
> using the "Visualization > Time-Frequency Grid" menu item in SIFT.
> Thanks for your advice in advance, to any and all who can think of some!
> James Jones-Rounds
> Laboratory Manager
> Human Development EEG and Psychophysiology (HEP) Laboratory,
> Department of Human Development,
> Cornell University | Ithaca, NY
> eeg at cornell.edu
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