[Mne_analysis] Negative Weighted Phase Lag Index Values

[Andrea Brovelli]

Dear all,

I don't know the implementation in MNE, but, as far as I know, the WPLI 
ranges between between -1 and 1 (see Fig. 1C in Vinck, Neuroimage 2011). 
The same is for the imaginary coherence (Nolte, Clin Neurophysiol 2004).

The strength of phase-synchronization can be indexed by the magnitude 
(or squared value) of the WPLI.

bye

Andrea




Le 14-Jun-17 à 7:51 PM, Eric Larson a écrit :
> Yes it looks like WPLI should be bounded by 0 and 1. Can you open an 
> MNE issue so we can look into it further?
>
> Eric
>
>
> On Wed, Jun 14, 2017 at 1:28 PM, Stout, Jeffrey <jstout at mcw.edu 
> <mailto:jstout at mcw.edu>> wrote:
>
>     We are running analyses on resting state MEG data and we are
>     finding negative values in the weighted phase lag index (wpli)
>     measure.  We have also run this data using the phase lag index
>     (PLI) measure and do not see any values below zero.  I thought
>     that both the PLI and WPLI should be defined from 0 to 1. 
>     Although the negative values tend to be small, we are seeing this
>     across many subjects.
>
>     wpli=np.load('connmat_wpli2_debiased13_30hz_run1.npy')
>
>     np.min(wpli), np.max(wpli)
>
>     Out[22]: (-0.0048496421426467845, 0.14954351856205442) <<<<<<<<<
>     WPLI minimum value below Zero
>
>     pli=np.load('connmat_pli13_30hz_run1.npy')
>
>     np.min(pli), np.max(pli)
>
>     Out[24]: (0.0, 0.21375066880684856) <<<<<<<<< PLI minimum value
>     equals zero
>
>     Is this a correct finding?  Any insight would be helpful.
>
>     Thank you,
>
>     Jeff Stout
>
>
>     _______________________________________________
>     Mne_analysis mailing list
>     Mne_analysis at nmr.mgh.harvard.edu
>     <mailto:Mne_analysis at nmr.mgh.harvard.edu>
>     https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis
>     <https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis>
>
>
>     The information in this e-mail is intended only for the person to
>     whom it is
>     addressed. If you believe this e-mail was sent to you in error and
>     the e-mail
>     contains patient information, please contact the Partners
>     Compliance HelpLine at
>     http://www.partners.org/complianceline
>     <http://www.partners.org/complianceline> . If the e-mail was sent
>     to you in error
>     but does not contain patient information, please contact the
>     sender and properly
>     dispose of the e-mail.
>
>
>
>
> _______________________________________________
> Mne_analysis mailing list
> Mne_analysis at nmr.mgh.harvard.edu
> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis
>
>
> The information in this e-mail is intended only for the person to whom it is
> addressed. If you believe this e-mail was sent to you in error and the e-mail
> contains patient information, please contact the Partners Compliance HelpLine at
> http://www.partners.org/complianceline . If the e-mail was sent to you in error
> but does not contain patient information, please contact the sender and properly
> dispose of the e-mail.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20170614/cf8d82c5/attachment-0001.html