[FieldTrip] surrogates for Phase lag index

[Bastien Boutonnet]

That makes sense. How would you implement phase-randomisation? Is it
similar to estimating the connectivity between the same pairs of electrodes
but with data coming from different trials? Or even simpler?

My interest to know about PLI/wPLI however still holds.

B

–
Bastien Boutonnet, Ph. D.
Postdoctoral Research Associate
Department of Psychology
University of Wisconsin, Madison
bastienboutonnet.com


On 9 July 2014 14:42, HINDRIKS, RIKKERT <rikkert.hindriks at upf.edu> wrote:

> Constructing surrogate time-series for PLV is more straightforward since,
> in this case, the nullhypothesis is the absence of phase-locking.
> Surrogate pairs of time-series can be constructed for example by
> phase-randomization in the Fourier domain.
>
> Rikkert
>
>
> On Wed, Jul 9, 2014 at 9:01 PM, Bastien Boutonnet <bastien.b1 at gmail.com>
> wrote:
>
>> I guess I will tag along to this discussion, in saying that I have been
>> having the same burning question for a while.
>>
>> My issues have been along those lines: when I run some kinds of
>> connectivity analyses (be it PLI, wPLI or PLV), how do I make sure the
>> values I obtain are "legal" (or different from 0).
>>
>> B
>>
>> –
>> Bastien Boutonnet, Ph. D.
>> Postdoctoral Research Associate
>> Department of Psychology
>> University of Wisconsin, Madison
>> bastienboutonnet.com
>>
>>
>> On 9 July 2014 13:39, HINDRIKS, RIKKERT <rikkert.hindriks at upf.edu> wrote:
>>
>>> Hi Lidia,
>>>
>>> I have the same question and I don't think the answer is trivial: one
>>> would have to construct pairs of surrogate time-series under the
>>> nullhypothesis of zero phase-lag-index. With other words: construct
>>> pairs of time-series who's instantaneous phases are coupled
>>> to the same extent as the recorded time-series but with zero lag. In my
>>> case, the question is how to test for a significant lag via the
>>> cross-correlation function.
>>>
>>>
>>> Kind regards,
>>> Rikkert
>>>
>>>
>>> On Wed, Jul 9, 2014 at 8:18 PM, Lidia Mijas <lid.mijas at gmail.com> wrote:
>>>
>>>> Hi all,
>>>>
>>>> I am wondering if fieldtrip has any options for computing surrogates?
>>>> I am tryng to assess confidence level for my Phase Lag Index results (
>>>> to determine whether it is significantly larger then 0)
>>>>
>>>> But maybe someone has a better idea how to do it?
>>>> Not sure if it matters so just to mentioned that my PLI was computed at
>>>> the source level on beamformed signals.
>>>>
>>>> Many thanks for any suggestion.
>>>>
>>>> Lidia
>>>>
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>>>>
>>>
>>>
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>>
>>
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