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Dear Yuval,<br>
<br>
I have to admit that I did not look at the matlab routines.<br>
In item 2 I suppose that the covariance is calculated for each trial
then averaged. In item 3 I would like to calculate the covariance
from all the signal (the trials being concatenated).<br>
<br>
Jean-Michel<br>
<br>
Le 22/03/11 05:47, Yuval Harpaz a écrit :
<blockquote
cite="mid:AANLkTiktUAfHVs+_d9HmysquBRcdkOMqYmsYL1hC0vFg@mail.gmail.com"
type="cite">
<div dir="ltr">Dear Jean Michel
<div>As far as I know you can do it on an averaged data
structure (item 1) or do the same with the data structure
before averaging (3). I did not understand what you meant by
2. </div>
<div><br>
</div>
<div>Yuval<br>
<br>
<div class="gmail_quote">On 21 March 2011 22:58, Jean-Michel
Badier <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:jean-michel.badier@univmed.fr">jean-michel.badier@univmed.fr</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div text="#000000" bgcolor="#ffffff"> Dear fieldtrip
users,<br>
<br>
There are different ways of estimating the covariance
for LCMV calculation.<br>
If I am correct: <br>
<br>
1. As suggested in one of the tutorial one can apply the
calculation of the covariance directly on the average
data (for the different periods of interest that are at
least a base line and the period of interest).<br>
<br>
2. Estimate the covariance from the average of the
covariance rather than the covariance of the average
using cfg.keeptrials = "yes"<br>
<br>
3. Estimate the covariance from the whole trials
concatenated together. <br>
Is there an easy way to do that in fieldtrip (beside
create a new data set of one trial constituted of all
the trials)?<br>
<br>
Thanks<br>
<br>
Jean-Michel<br>
<br>
<div>
<address>-- </address>
<address style="margin-bottom: 0cm;">Jean-Michel
Badier PhD</address>
<address style="margin-bottom: 0cm;"><br>
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<address style="margin-bottom: 0cm;" align="LEFT"><font
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size="3">Laboratoire
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<address style="margin-bottom: 0cm;" align="LEFT"><font
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face="Times Roman, serif"><font size="2">Service
de Neurophysiologie Clinique. </font></font></font>CHU
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<br>
<br clear="all">
<br>
-- <br>
<div dir="ltr">Y.Harpaz<br>
<br>
a link to the BIU MEG lab:<br>
<a moz-do-not-send="true"
href="http://faculty.biu.ac.il/%7Egoldsa/index.html"
target="_blank">http://faculty.biu.ac.il/~goldsa/index.html</a>
<div>
<div><br>
</div>
<div> " Why, Dan," ask the people in Artificial
Intelligence, "do you waste your time conferring with
those neuroscientists? They wave their hands about
information processing and worry about where it
happens, and which neurotransmitters are involved, and
all those boring facts, but they haven't a clue about
the computational requirements of higher
cognitive functions." "Why," ask the neuroscientists,
"do you waste your time on the fantasies of Artificial
Intelligence? They just invent whatever machinery they
want, and say unpardonably ignorant things about the
brain." The cognitive psychologists, meanwhile, are
accused of concocting models with neither biological
plausibility nor proven computational powers; the
anthropologists wouldn't know a model if they saw one,
and the philosophers, as we all know, just take in each
other's laundry, warning about confusions they
themselves have created, in an arena bereft of both data
and empirically testable theories. With so many idiots
working on the problem, no wonder consciousness is
still a mystery.<i> Philosopher Daniel Dennet,
consciousness explained, pp. 225</i></div>
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