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Hi Johanna, and everyone reading,<br>
<br>
Thanks very much for that insight re cfg.supdip option. I'll have a
look and try it.<br>
<br>
Best,<br>
May<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 21/03/2014 11:00,
<a class="moz-txt-link-abbreviated" href="mailto:fieldtrip-request@science.ru.nl">fieldtrip-request@science.ru.nl</a> wrote:<br>
</div>
<blockquote
cite="mid:mailman.0.1395399622.16808.fieldtrip@science.ru.nl"
type="cite"><br>
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<div class="headerdisplayname" style="display:inline;">Subject:
</div>
Re: [FieldTrip] fieldtrip Digest, Vol 40, Issue 33</td>
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<div class="headerdisplayname" style="display:inline;">From:
</div>
Johanna Zumer <a class="moz-txt-link-rfc2396E" href="mailto:johanna.zumer@gmail.com"><johanna.zumer@gmail.com></a></td>
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<div class="headerdisplayname" style="display:inline;">Date:
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20/03/2014 13:03</td>
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<div class="headerdisplayname" style="display:inline;">To:
</div>
FieldTrip discussion list <a class="moz-txt-link-rfc2396E" href="mailto:fieldtrip@science.ru.nl"><fieldtrip@science.ru.nl></a></td>
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<div dir="ltr">Hi May, Inna, everyone,
<div><br>
</div>
<div>I'm not sure exactly what Inna meant by the ROI,
specifically whether the ROI was applied to source space or
to sensors. Applying a ROI to sources will not work: the
beamformer result at one location in the brain is the same
irrespective of where else you also compute a beamformer
result. However, perhaps Inna meant ROI over channels
(e.g. left channels for the left auditory cortex). If so,
then as she says, it will reduce the problem a bit but it
will still be there. See cfg.supchan in ft_sourceanalysis.</div>
<div><br>
</div>
<div>Indeed the method by Dalal et al. was initially
implemented in the <a moz-do-not-send="true"
href="http://www.nitrc.org/projects/nutmeg/"
target="_blank">NUTMEG </a>software (which is compatible
with FieldTrip). However, it is also now implemented in
FieldTrip by using the cfg.supdip option in
ft_sourceanalysis, which allows you to suppress a region
(e.g. right auditory cortex) so that you can estimate
activity elsewhere (e.g. left auditory cortex).</div>
<div><br>
</div>
<div>Cheers,</div>
<div>Johanna</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
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<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">2014-03-20 11:47 GMT+00:00 Heng-Ru
May Tan <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:Heng-RuMay.Tan@glasgow.ac.uk"
target="_blank">Heng-RuMay.Tan@glasgow.ac.uk</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
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<div text="#333300" bgcolor="#FFFFFF"> Hi Inna,<br>
<br>
Thanks for the suggestions re using ROI beamforming
separately and references. I'll give it a go.<br>
<br>
BTW, I wonder if those beamforming algorithms e.g. Dalal
et al2006 (IEEE biomed. eng.) might have already been
implemented somewhere... or might it be something that
fieldtrip might/could consider adding to their
sourceanalysis options? =)<br>
<br>
Thanks,<br>
May<br>
<br>
<br>
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<div style="display:inline">Subject: </div>
Re: [FieldTrip] Source localizing auditory
steady state responses</td>
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<td>
<div style="display:inline">From: </div>
"McGowin, Inna" <a moz-do-not-send="true"
href="mailto:mcgoiv0@wfu.edu"
target="_blank"><mcgoiv0@wfu.edu></a></td>
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<div style="display:inline">Date: </div>
19/03/2014 17:21</td>
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<div style="display:inline">To: </div>
FieldTrip discussion list <a
moz-do-not-send="true"
href="mailto:fieldtrip@science.ru.nl"
target="_blank"><fieldtrip@science.ru.nl></a></td>
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<div><br>
<div>Hey May,<br>
</div>
Beamorming on correlated sources is my
interest too. The problem is that most
beamformers (I deal with SAM and vector
beamformer) are going to suppress or/and
misplace any correlated source. The way I
deal with this problem is by creating a
region of interest (around primary
auditory cortex) and beaformer over each
ROI separately. The signal correlation
problem is still there but with a lesser
extant (I think). Here is a great article
on this topic:<br>
Beamformer reconstruction of correlated
sources using a modified source model<br>
</div>
and <br>
Modified Beamformers for Coherent Source
Region Suppression<br>
<br>
</div>
Also if I localize evoked responses I always
prefer dipole fitting over other methods, you
could try the moving dipolar fitting method
and have your wave former from the dipole
t-course.<br>
</div>
Let me know how it will go for you.<br>
</div>
Cheers,<br>
</div>
Inna<br>
<div>
<div>
<div>
<div>
<div><br>
</div>
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<br clear="all">
<div>Inna McGowin<br>
</div>
<br>
<br>
On Wed, Mar 19, 2014 at 12:17 PM, Heng-Ru May Tan <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:Heng-RuMay.Tan@glasgow.ac.uk"
target="_blank">Heng-RuMay.Tan@glasgow.ac.uk</a>></span>
wrote:<br>
<br>
Hi All,<br>
I am trying to localize frequency specific ASSR but
have not been successful in doing so with the 'mne'
method in the ft_sourceanalysis.<br>
At the sensor-level the topo plots show clear
bilateral generators.<br>
<br>
Is it possible to localize the bilateral sources using
beamforming? And would I need to create a different
forward model?<br>
Additionally, I would also like to retrieve the source
signals and ideally comparing between 2 time periods
within the same trial.<br>
<br>
I would appreciate if someone could advise or comment
on how best to go about doing so.<br>
<br>
Thanks,<br>
May<span><font color="#888888"><br>
</font></span></blockquote>
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