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Dear Shogo,<br>
<br>
As far as I know, there is no built-in function to compute a
phase-locking factor in FieldTrip, so I am afraid that you have to
program this on your own. However, all values you need can be
collected in FieldTrip. You can either apply a Hilbert transform on
your data to obtain instanenous phase (set cfg.hilbert='yes' prior
to calling <i>ft_preprocessing</i>) or get the phase information
out from the fourierspectrum (cfg.output='fourier' prior to calling
<i>ft_freqanalysis</i>). In both case, you should be able to get the
phase out by calling the Matlab built-in function <i>angle()</i>.
Computing the PLF should then be rather straight-forward.<br>
<br>
Also, maybe this can be of help:<br>
<a class="moz-txt-link-freetext" href="http://en.wikipedia.org/wiki/Von_Mises_distribution">http://en.wikipedia.org/wiki/Von_Mises_distribution</a><br>
<br>
Hope this helps! Best,<br>
Jörn<br>
<br>
On 1/13/2012 2:49 AM, 平野 昭吾 wrote:
<blockquote
cite="mid:75DF5877-BB2D-4918-A4C0-2A66F7EDCF8E@npsych.med.kyushu-u.ac.jp"
type="cite">
<pre wrap="">Hi everyone!
I'm a FieldTrip beginner and I have a question.
I'm sure I can estimate time frequency power with FieldTrip.
But I don't know how I can estimate time-frequency phase locking factor.
phase locking factor is defined as following equation.
Phase-locking(t)=1/N x |Σz(t)|, where N is the number of epochs and z(t) refers to the continuous phase of a single trial.
Here, z is a complex value on the unit circle, i.e., z=exp(jq), where q is the phase of an oscillation and j is the imaginary unit (e.g. Tallon-baudry et al., 1996).
Does anyone know how to calculate this phase locking factor with FieldTrip?
Any answer will help me.
Best regards,
Shogo Hirano
Department of Neuropsychiatry
Graduate school of medical sciences
Kyushu University
Fukuoka, Japan
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</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands
Contact:
E-Mail: <a class="moz-txt-link-abbreviated" href="mailto:jm.horschig@donders.ru.nl">jm.horschig@donders.ru.nl</a>
Tel: +31-(0)24-36-68493
Web: <a class="moz-txt-link-freetext" href="http://www.ru.nl/donders">http://www.ru.nl/donders</a>
Visiting address:
Trigon, room 2.30
Kapittelweg 29
NL-6525 EN Nijmegen
The Netherlands</pre>
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