Dear Fred and Max,<div><br></div><div>To follow up on this: we have identified and fixed the problem, as of last night's release. You can see the issue here: <a href="http://bugzilla.fcdonders.nl/show_bug.cgi?id=1858">http://bugzilla.fcdonders.nl/show_bug.cgi?id=1858</a> This is a related, but different, bug than the 1288 I posted earlier.</div>
<div><br></div><div>To summarize: all output of ft_megplanar should now be recognized correctly as planar gradient data in subsequent steps. If you have data that was generated by ft_megplanar prior to this fix, you can easily patch it by doing:</div>
<div><br></div><div>data.grad.type = 'ctf275_planar';</div><div><br></div><div>(or xxxx_planar for other axial gradiometer acquisition systems).</div><div><br></div><div>Feel free to reopen bug 1858 if the issue has not been resolved.</div>
<div><br></div><div>Best,</div><div>Eelke</div><div class="gmail_extra"><br><br><div class="gmail_quote">On 23 November 2012 09:48, Eelke Spaak <span dir="ltr"><<a href="mailto:eelke.spaak@donders.ru.nl" target="_blank">eelke.spaak@donders.ru.nl</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear Fred and Max,<br>
<br>
This is a known bug in ft_senstype, and people are working on fixing<br>
it. See bugzilla: <a href="http://bugzilla.fcdonders.nl/show_bug.cgi?id=1288" target="_blank">http://bugzilla.fcdonders.nl/show_bug.cgi?id=1288</a> .<br>
If you have anything to add to the bug reports over there, that could<br>
be helpful.<br>
<br>
For now, Max's workaround seems to do the trick.<br>
<br>
Best,<br>
Eelke<br>
<br>
On 22 November 2012 19:36, Stenner, Max-Philipp<br>
<div class="HOEnZb"><div class="h5"><<a href="mailto:max-philipp.stenner@med.ovgu.de">max-philipp.stenner@med.ovgu.de</a>> wrote:<br>
> Dear Fred,<br>
><br>
> I encountered a similar problem with my CTF275 data and one broken sensor before ft_freqanalysis of the planar (uncombined) data. "Confirming" the channel type with<br>
><br>
> data.grad.chantype = ft_senstype(data);<br>
><br>
> solved the problem (although I have to admit that I never investigated where in the ft script the problem arose).<br>
><br>
> Cheers,<br>
> Max<br>
><br>
> ________________________________________<br>
> Von: <a href="mailto:fieldtrip-bounces@science.ru.nl">fieldtrip-bounces@science.ru.nl</a> [<a href="mailto:fieldtrip-bounces@science.ru.nl">fieldtrip-bounces@science.ru.nl</a>]" im Auftrag von "Frederic Roux [<a href="mailto:f.roux@bcbl.eu">f.roux@bcbl.eu</a>]<br>
> Gesendet: Donnerstag, 22. November 2012 14:19<br>
> Bis: FieldTrip discussion list<br>
> Betreff: [FieldTrip] planar gradients<br>
><br>
> Dear all,<br>
><br>
> I would like to follow up this post with another question<br>
> related to the planar gradients.<br>
><br>
> I am working on data aquired with a CTF 275 system but at<br>
> the time of the acquisition there was a number of sensors<br>
> that were broken.<br>
><br>
> So I end up with n = 258 channels.<br>
><br>
> After running the ft_megplanar function I get n = 516 channels.<br>
><br>
> However, if I try to combine the gradients with<br>
> ft_combineplanar<br>
><br>
> I get an error saying that I am not providing ctf275_planar but<br>
> ctf275 data.<br>
><br>
> Is the fact that I do not have n = 275 sensors but 258 confusing<br>
> the ft_combineplanar function, or is this related to something else?<br>
><br>
><br>
> Best,<br>
><br>
> Fred<br>
><br>
> ----- Original Message -----<br>
> From: "Eelke Spaak" <<a href="mailto:eelke.spaak@donders.ru.nl">eelke.spaak@donders.ru.nl</a>><br>
> To: "FieldTrip discussion list" <<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>><br>
> Sent: Wednesday, November 21, 2012 12:47:25 PM<br>
> Subject: Re: [FieldTrip] ft_freqstatistics tutorial question<br>
><br>
> Dear Nenad,<br>
><br>
> Strictly speaking, planar gradient transformation is not necessary, so<br>
> you can just skip those steps if you really want to. However, if you<br>
> have axial gradiometer data (as I seem to recall from your earlier<br>
> posts) and want to do TF-analysis and -statistics on sensor level, I<br>
> would strongly recommend applying a planar gradient transformation.<br>
><br>
> Axial gradiometer data will produce maximal deflections (of opposite<br>
> polarity) on both sides of a current dipole, while planar gradiometer<br>
> data produces a positive maximum exactly above the source. If you<br>
> apply TF-analysis to axial gradiometer data, you will get two<br>
> spatially separated 'blobs' where there was only a single oscillating<br>
> dipole in the brain. If you look at power (as is typically done), you<br>
> will lose the polarity information, and hence interpreting the power<br>
> topography in terms of brain is nearly impossible with axial gradient<br>
> data.<br>
><br>
> Best,<br>
> Eelke<br>
><br>
> On 21 November 2012 11:30, Nenad Polomac <<a href="mailto:polomacnenad@gmail.com">polomacnenad@gmail.com</a>> wrote:<br>
>> Dear all,<br>
>><br>
>> I have one doubt. I want to calculate ft_freqstatistics on my MEG date<br>
>> obtained form ft_freqanalysis. However, I see now in ft_freqstatistics<br>
>> tutorial that you suggest that operation should be done on planar gradient<br>
>> data. So, the first ft_megplanar and then ft_freqanalysis, ft_combineplanar<br>
>> and ft_freqstatistics. My question is, does this step of calculating planar<br>
>> gradients for time frequency analysis is necessary or not? Could I apply<br>
>> statistic on the data from ft_freqanalysis without any involvement of planar<br>
>> gradients calculation.<br>
>> Thank you in advance!<br>
>><br>
>> All the best!<br>
>><br>
>> Nenad<br>
>><br>
>><br>
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</div></div></blockquote></div><br></div>