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Hello,
I do not disagree with your assertion about the
MNI space in general. However, if you can tell
the exact location of the gyri (frontal gyri
etc.) by looking at the averaged T1 images of
your sample (which is a very good choice too),
well do it. My intention is to report the BAs
with reference to Taliarach (however guessy in
Talairach) as well as visual inspection so that
we can compare our results in terms of guessed
BAs. I personally prefer to report MNI space
coordinates plus the converted coordinates. If
you are not interested in BAs and want to report
the general position of the blobs
(postero-lateral prefrontal for instance) plus
the MNI space and your readers are happy with it,
then do it. The main objective is that we all
should have (which you obviously have) is to make
sense of our findings and share them.
The publication of our papers depends on the
reviewers and their understanding of SPM. Some
times SPM analyses results with completely out
of line interpretations of the SPM users are
published and then referred to by the others. This is scary!
In general I agree with your point 200% that we
can refer to MNI space. But, if you want to
report BAs just by looking at the blobs super
imposed on the mean T1 images (or other images or
the SPM template) of your sample, I become
concerned. The reference to the guessed BAs in
Talairach creates a common
guessed reference. General reference to the
position of the blobs in MNI space is closer to
the real world (I definitely agree) is still a
common reference as long as the BAs will not be
the authors' guess. That is, Talairach will be
our reference for guessing until a better way
will be figured out by scientists like yourself
and will be used by people like myself. If you
want to report your results based on MNI
coordinates, then I would not report BAs. This is a very good discussion!
Cheers,
Shary
At 17/03/2006 Friday 09:55 AM, Simon B. Eickhoff wrote:
>Dear In, dear Shary, dear list
>
> > I have to disagree colleagues. There are
> > publications about differences between the MNI
> > and Talairach space (MNI is larger). I do agree
> > that Talairach conversion is not perfect, but it
> > is better than not converting.
>
>
>
>I guess this is the main question. Is there
>anything at all to be gained from a conversion
>into talairach space? Reportin MNI coordinates
>is perfectly fine, since the MNI space is a well
>defined reference space and in addition also
>more valid, since you omitt one source of error/variance.
>
>
>
>
>
> > In addition to
> > the conversion, I super-impose the blobs onto the
> > SPM template used for normalization and double
> > che the location of the significant blobs. This
> > way, you can see some small errors (the blob is
> > moved to left or right a bit) and very few more
> > significant errors (in higher slices).
>
>
>
>A very important point. You should always
>visually check your blobs, preferably also by
>comparison with your subjects mean normalised T1 and EPI image (distortions).
>
>
>
>
>
> > This way,
> > at least, we get closer to the real world and
> > report a bit more realistic location of the
> > blobs.
>
>
>
>Is Talairach space really closer to the real
>world? The Talairach atlas shows a hand-made
>drawing of a single disected post-mortem brain
>with estimated (i.e. guessed !) locations of Brodmann's areas.
>
>
>
> > But, if you just use only the MNI
> > coordinates to localize the blobs, you are more
> > likely to report the wrong position of the blobs
> > by referring to the Talairach atlas (frontal gyus
> > instead of insula etc. in my experience). Please be aware of this.
>
>As detailed above, refering to the Talairach
>atlas will not really help you much in
>localising your blobs, as you might as well (and
>if you are experienced in neuroanatomy, probably
>with a much higher precision) estimate the
>cytoarchitectonic location of your blobs
>yourself. Just to repeat myself: The Talairach
>brain is a drawing of individual slices, where
>the authors indicated the presumed location of
>the areas shown in Brodmann's (schematic !, two
>dimensional !) map. There was neither a
>histological basis nor a standarised procedure, just pure guesswork.
>
>
>
>Just my opinion
>
>Simon
>
>
>
>
>
>
>
> >
> > Cheers,
> > Shary
> > P.S.- Please look at the following references:
> >
> > Main references for differences between MNI and Talairach:
> >
> > http://www.mrc-cbu.cam.ac.uk/Imaging/Common/mnispace.shtml
> > (Viewed on September 20, 2005)
> >
> > Brett M, Johnsrude IS, Owen AM. The problem of
> > functional localization in the human brain.
> > Nat Rev Neurosci. 2002 Mar;3(3):243-9. Review.
> >
> >
> > Reference for MNI to Talairach transformation:
> >
> > Brett M, Christoff K, Cusack R and Lancaster J
> > 2001 Using the Talairach atlas with the MNI template Neuroimage
> > 13 85
> >
> >
> ********************************************************************************************************************
>
> >
> > At 17/03/2006 Friday 09:20 AM, Simon B. Eickhoff wrote:
> >
> > >Dear In,
> > >
> > >I totally agree with Alexanders opinion, there
> > >is no need to convert MNI coordinates into
> > >Talairach space. Why would you want to do that?
> > >
> > >Since you made your analysis and inference in
> > >MNI space, you should also report your results
> > >in this reference system. Any further conversion
> > >(in particular any transformation involving only
> > >linear normalisation) would furthermore
> > >introduce an additional error into your reported coordinates.
> > >
> > >Just report MNI coordinates in your paper (and
> > >say so !) and you should be fine.
> > >
> > >Hope this helps
> > >Simon
> > >
> > >
> > >-----------------------------------------
> > >
> > >Simon Eickhoff
> > >Institut for Medicine (IME); Research Center Jülich
> > >Leo-Brandt-Str. 5; 52425 Juelich, Germany
> > >Phone + 49 2461-61-5219 / Fax + 49 2461-61-2820
> > >e-mail: [log in to unmask] /
> > ><[log in to unmask])" >mailto:[log in to unmask]>[log in to unmask]
> > >
> > >
> > >
> > >
> > >
> > >
> > >----- Original Message -----
> > >
> > >From: "Hammers, Alexander" <[log in to unmask]>
> > >
> > >Date: Friday, March 17, 2006 1:57 pm
> > >
> > >Subject: Re: [SPM] Converting MNI coordinates to Talairach
> > coordinates>
> > > > Dear In Kang,
> > > >
> > > >
> > > > Please note that converting MNI (whether SPM2 or SPM5 or
> > SPM99) to
> > > > Talairach is at best a dodgy business - are you sure you need to?
> > > > It's perfectly acceptable to publish MNI coordinates.
> > > >
> > > > If you really want to, there are several points to consider -
> > > > Matthew Brett's seminal web page lists them all:
> > > > http://www.mrc-cbu.cam.ac.uk/Imaging/Common/mnispace.shtml
> > > > He also provides formulae on how to do it.
> > > >
> > > > If you do convert to Talairach, please make this very clear in the
> > > > paper and, in particular, quote the method / formula you used.
> > > >
> > > > Good luck and best wishes,
> > > >
> > > > Alexander
> > > >
> > > > -----Original Message-----
> > > > From: SPM (Statistical Parametric Mapping)
> > > > [mailto:[log in to unmask]]OnBehalf Of ika16
> > > > Sent: 17 March 2006 11:08
> > > > To: [log in to unmask]
> > > > Subject: [SPM] Converting MNI coordinates to Talairach coordinates
> > > >
> > > >
> > > > Dear All.
> > > >
> > > > I have coordinates for an image already normalized to SPM5-MNI
> > space.> > Would anyone give help for converting MNI coordinates to
> > > > Talairach
> > > > coordinates on SPM5 or SPM2?
> > > >
> > > >
> > > > Any help would be most appreciated.
> > > >
> > > > Cheers.
> > > >
> > > > ----------------------------------------
> > > > In Kang
> > > >
> > > > Ph.D Statistics Student
> > > > Department of Mathematics and statistics
> > > > University of Canterbury
> > > > Private Bag 4800
> > > > Christchurch New Zealand
> > > > Tel: +64 3 364 2987 ext 8873
> > > >
> >
>
>-----------------------------------------
>
>Simon Eickhoff
>Institut for Medicine (IME); Research Center Jülich
>Leo-Brandt-Str. 5; 52425 Juelich, Germany
>Phone + 49 2461-61-5219 / Fax + 49 2461-61-2820
>e-mail: [log in to unmask] / [log in to unmask]
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