# calculating phase locking values on MNE source	estimate within labels- using mne.minimum\_norm.source\_induced\_power

**URL:** <https://mne.discourse.group/t/calculating-phase-locking-values-on-mne-source-estimate-within-labels-using-mne-minimum-norm-source-induced-power/1387>\
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**Created:** [December 27, 2017, 9:58am UTC](https://mne.discourse.group/t/calculating-phase-locking-values-on-mne-source-estimate-within-labels-using-mne-minimum-norm-source-induced-power/1387 "2017-12-27T09:58:07Z")\
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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [December 27, 2017, 9:58am UTC](https://mne.discourse.group/t/calculating-phase-locking-values-on-mne-source-estimate-within-labels-using-mne-minimum-norm-source-induced-power/1387/1 "2017-12-27T09:58:07Z")

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Hi all and happy holidays:

I am trying to render a a time- frequency map containing phase locking values (0-1) from label files containing SVD?s of MNE source estimate timeseries. I began with the example:

[https://martinos.org/mne/stable/auto\_examples/time\_frequency/plot\_source\_label\_time\_frequency.html#sphx-glr-auto-examples-time-frequency-plot-source-label-time-frequency-py](https://martinos.org/mne/stable/auto_examples/time_frequency/plot_source_label_time_frequency.html#sphx-glr-auto-examples-time-frequency-plot-source-label-time-frequency-py)

which gives ITC for evoked plus induced and induced alone using mne.minimum\_norm.source\_induced\_power. my questions are the following parameters:  
If I choose baseline =None and baseline\_mode=None, will I get PLV values of 0-1 across all the epoch where the locking is relative to stimulus onset (i.e. at time zero).

2) zero\_mean when should this be used? are all wavelets not zero-meaned by default?  
3) the parameter prepare: When calling a saved inverse operator file at the beginning of a script like the example as in my caee executing the full inverse\_operator = read\_inverse\_operator(inv\_fname)  
src = inverse\_operator['src?] initially and then looping thought the labels. Can setting the Prepare?= True be done and will it save time?

thanks in advance

david

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [December 27, 2017, 10:33am UTC](https://mne.discourse.group/t/calculating-phase-locking-values-on-mne-source-estimate-within-labels-using-mne-minimum-norm-source-induced-power/1387/2 "2017-12-27T10:33:31Z")

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hi David,

see inline comments

> I am trying to render a a time- frequency map containing phase locking  
> values (0-1) from label files containing SVD?s of MNE source estimate  
> timeseries. I began with the example:
> 
> [Page Redirection](https://martinos.org/mne/stable/auto_examples/time_frequency/plot_source_label_time_frequency.html#sphx-glr-auto-examples-time-frequency-plot-source-label-time-frequency-py)
> 
> which gives ITC for evoked plus induced and induced alone using  
> mne.minimum\_norm.source\_induced\_power. my questions are the following  
> parameters:  
> If I choose baseline =None and baseline\_mode=None, will I get PLV values  
> of 0-1 across all the epoch where the locking is relative to stimulus onset  
> (i.e. at time zero).

yes

> 2) zero\_mean when should this be used? are all wavelets not zero-meaned by  
> default?

very often Morlet wavelets are used in Neuroscience without the \kappa\_\sigma  
in defintion from [Morlet wavelet - Wikipedia](https://en.wikipedia.org/wiki/Morlet_wavelet)

this constant makes sure the wavelets are zero mean.

it's not a big problem if you use many cycles (lets say \> 5) but otherwise  
your wavelet coefficient will capture a DC component.

Historically I had written the code without the \kappa\_\sigma and when I added  
it, I made it an option with zero\_mean. I suggest to always use zero\_mean=True.

> 3) the parameter prepare: When calling a saved inverse operator file at the  
> beginning of a script like the example as in my caee executing the full  
> inverse\_operator = read\_inverse\_operator(inv\_fname)  
> src = inverse\_operator['src?] initially and then looping thought the  
> labels. Can setting the Prepare?= True be done and will it save time?

yes if you prepare the inverse operator you should save time.

HTH  
Alex