<div dir="ltr"><p class="" style="margin:0cm 0cm 0.0001pt 18pt;text-align:justify;direction:ltr">Dear Jörn,</p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;text-align:justify;direction:ltr">Thank
you for your kind answer!</p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr"> </p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr">From what
we saw on several links it is customary to perform the interpolation before normalisation,
both before statistical analysis (e.g. <a href="http://fieldtrip.fcdonders.nl/tutorial/introduction">http://fieldtrip.fcdonders.nl/tutorial/introduction</a>)
or just before plotting as you mentiones (e.g. <a href="http://fieldtrip.fcdonders.nl/tutorial/beamformer">http://fieldtrip.fcdonders.nl/tutorial/beamformer</a>).</p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr"> </p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr">The reason
we wanted <b>to interpolate before normalising</b> is that interpolation relies
on anatomical data, hence it is not possible to use ft_volumenormalise on pure
"source" structure (yet it is possible using it on "interpolated
source" structure).</p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr"> </p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr">The reason
we wanted to do the <b>normalisation</b> <b>per trial</b> is the following: we
want to compare the source structure for each condition. In principle, we could
have performed the source analysis over all trials and get the AVERAGE source
per subject per condition, and then compare these two groups (source condition
1, source condition 2). However, we have too few subjects, and so we thought it
could be best to compare the source reconstructions of ALL trials over ALL
patients in both conditions. Does this make any sense to you?</p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr"> </p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr">Best,</p>
<p class="" style="margin:0cm 0cm 0.0001pt 18pt;direction:ltr">Aia and Roey</p></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Sep 3, 2013 at 1:46 PM, "Jörn M. Horschig" <span dir="ltr"><<a href="mailto:jm.horschig@donders.ru.nl" target="_blank">jm.horschig@donders.ru.nl</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 .8ex;border-left:1px #ccc solid;border-right:1px #ccc solid;padding-left:1ex;padding-right:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Dear Roey,<br>
<br>
of course there is a way, actual several. I don't see a reason why
you would want to do that though :) The interpolation purpose is
mainly for plotting, not for performing fancy statistics or other
analyses. In case you want to go to a finer spatial resolution,
I'd do the reconstruction on a finer grid (and there, you will be
faced with just physical and mathematical constraints in terms of
spatial accuracy). That way, your reconstruction will be at least
based on a physical model, not on some 'weird' linear
interpolation.<br>
<br>
Anyway, to answer your question:<br>
First, there is a cfg.parameter field, with which you can specify
the parameter. If that does not work, the easiest way for you
would be to go to the code of ft_sourceinterpolate at line 171,
copy the lines up to 184 and put these into your own function. You
would need to change them appropriately, so that you loop over
trials. As I said, there are other ways, but that would be the
most elegant, fastest (computationally) and easiest to understand.<br>
<br>
Best,<br>
Jörn<div><div class="h5"><br>
<br>
On 9/2/2013 4:54 PM, Roey Schurr wrote:<br>
</div></div></div>
<blockquote type="cite"><div><div class="h5">
<div dir="ltr">
<div>Hi all,</div>
<div><br>
</div>
<div>We are interested in comparing two source
reconstruction calculated using EEG records taken in two
different conditions (not ERP), from different subjects,
across the group.</div>
<div><br>
</div>
<div>As we see it, what we must do is the following:</div>
<div><br>
</div>
<div>1) <span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">ft_sourceanalysis
(for each condition in each subject, in all trials)</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">2)
ft_sourceinterpolate (the same)</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">3)
ft_volumenormalise (the same)</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">4) </span><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">ft_sourcegrandaverage</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">5) </span><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">ft_sourcestatistics</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%"><br>
</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:11pt;line-height:115%">The
problem is </span><span style="font-family:Calibri,sans-serif;font-size:14.44444465637207px;line-height:15.555556297302246px">ft_sourceinterpolate</span><span style="font-family:Calibri,sans-serif;font-size:14.44444465637207px;line-height:15.555556297302246px"> will
not interpolate each trial individually, as there is no way
to give it the "pow" field per trial.</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:14.44444465637207px;line-height:15.555556297302246px"><br>
</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:14.44444465637207px;line-height:15.555556297302246px">Is
there a way to performd the interpolation over the
anatomycal MRI per trial?</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:14.44444465637207px;line-height:15.555556297302246px"><br>
</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:14.44444465637207px;line-height:15.555556297302246px">Thank
you so much!</span></div>
<div><span style="font-family:Calibri,sans-serif;font-size:14.44444465637207px;line-height:15.555556297302246px">Aia
and Roey</span></div>
<span dir="RTL"></span><span dir="RTL" style="font-size:11pt;line-height:115%;font-family:Arial,sans-serif"><span dir="RTL"></span></span></div>
<br>
<fieldset></fieldset>
<br>
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</blockquote>
<br>
<br>
<pre cols="72">--
Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
FieldTrip Development Team
P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands
Contact:
E-Mail: <a href="mailto:jm.horschig@donders.ru.nl" target="_blank">jm.horschig@donders.ru.nl</a>
Tel: <a href="tel:%2B31-%280%2924-36-68493" value="+31243668493" target="_blank">+31-(0)24-36-68493</a>
Web: <a href="http://www.ru.nl/donders" target="_blank">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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