[FieldTrip] Question about Phase locking value

[Schoffelen, J.M. (Jan Mathijs)]

When you call ft_freqanalysis with ‘fourier’ in the cfg.method, followed by ft_sourceanalysis with ‘pcc’ in cfg.method, the source.avg.mom contains the fourier coefficients at the single taper level. A bunch of tapers constitute a single trial, the number of which depends on the smoothing parameter that you used in ft_freqanalysis.

Jan-Mathijs



J.M.Schoffelen, MD PhD
Senior Researcher, VIDI-fellow - PI, language in interaction
Telephone: +31-24-3614793
Physical location: room 00.028
Donders Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands




On 2 Feb 2018, at 01:12, Yaocong Duan <yaocong.duan at gmail.com<mailto:yaocong.duan at gmail.com>> wrote:

Hi Stephen,

Thank you for your response. I write something wrong in my previous email. the freq structure does have trails information. but then I do a source reconstruction and generate a source structure. phase locking value is calculated from the source structure directly. However, the source structure does not have any trails info (trails seems have been averaged).

source = ft_sourceanalysis(cfg, freq);
...
plv = ft_connectivityanalysis(cfg, souceSparse);


below are the freq structure generated by freq analysis, source structure generated by source analysis as well as the .avg field of source structure.


<image.png><image.png><image.png>

On 1 February 2018 at 18:02, Stephen Whitmarsh <stephen.whitmarsh at gmail.com<mailto:stephen.whitmarsh at gmail.com>> wrote:
Dear Yaocong,

To understand your question, it would be helpful if you post the output of the freqanalysis, i.e. your freq datastructure. It should contain a .pow field, which should be an array of structs, numbering your number of trials, right?

Cheers,
Stephen

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On 1 February 2018 at 18:31, Yaocong Duan <yaocong.duan at gmail.com<mailto:yaocong.duan at gmail.com>> wrote:
Hi All,

I am using Phase Locking Value to measure the connectivity between brain regions at the source level. I learned that the PLV is an average value over trails. In the fieldtrip code, I calculated a frequency model first, then do connectivity analysis with this freq model. The problem is I don’t see trails information in the freq model. So how do I get that phase locking result?

Below is my code. This code works, but I am confused about the question above.

<image.png>

Thanks in advance,
Yaocong

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