Dear Teresa,
"Franklin, Teresa" wrote:
>
> Hello All, I am looking for an 'easy' way to faultlessly determine
> anatomical regions. I am using spm '99 in MNI space. Once the images have
> been normalized, smoothed, etc... it is difficult to determine exact
> brodman's areas of activation. What I would love to do is plop my MNI space
> images down on top of an image labeled with Brodman's areas and tada! - i
> would have my answers. Does this atlas exist - or what is the next best
> thing? Thanks so much for you help. teri-)
Russ made the important point that Brodmanns areas are defined in terms
of cytoarchetecture, and this is variable from subject to subject. The
degree of this variation differs from region to region. Probablistic
maps are now being constructed in some labs (e.g. the Zilles lab in
Dusseldorf) by analyzing the cytoarchetectonic characteristics of human
brian tissue. One could use these to determine the probability of a
given activation being in a particular Brodmann area. For this to work,
these probability cytoarchetectonic maps from several individual brains
would have to be warped into ICBM space (maps in this form are not yet
generally available as far as I am aware).
However, it is perfectly valid to use gross (sulcual and gyral)
anatomical landmarks for localisation, because, depending on the region,
they sometimes form convenient boundaries between
functional/cytoarchetectonic regions. If you have access to structural
T1 scans of the subjects used in your functional study, you may be able
to do this on a subject-by-subject basis. I would recommend that you use
a good anatomical atlas as a resource for this - Duvernoy (1991) ('The
human brain : surface, three-dimensional sectional anatomy and MRI';
Wien : Springer-Verlag) is pretty good since the brain sections can be
viewed in the same planes of section as those in SPM (brains are
sectioned parallel to or perpendicular to the AC/PC plane).
Alternatively, you may be able to use probablistic maps of sulcal and
gyral anatomy. These do exist in ICBM space for some parts of the human
brain. For example,
1. Tomaiuolo F, MacDonald JD, Caramanos Z, Posner G, Chiavaras M, Evans
AC, Petrides M. Morphology, morphometry and probability mapping of the
pars opercularis of the inferior frontal gyrus: an in vivo MRI analysis.
Eur J Neurosci. 1999 Sep;11(9):3033-46.
2. Chiavaras MM, Petrides M. Orbitofrontal sulci of the human and
macaque monkey brain. J Comp Neurol. 2000 Jun 19;422(1):35-54.
3. Paus T, Otaky N, Caramanos Z, MacDonald D, Zijdenbos A, D'Avirro D,
Gutmans D, Holmes C, Tomaiuolo F, Evans AC. In vivo morphometry of the
intrasulcal gray matter in the human cingulate, paracingulate, and
superior-rostral sulci: hemispheric asymmetries, gender differences and
probability maps. J Comp Neurol. 1996 Dec 23;376(4):664-73.
You may also wish to access the 'Talairach Daemon' website which also
deals with probablistic gross anatomy in ICBM space. This will allow you
to type in the coordinates of your activation and obtain a probability
values for specific grossly defined anatomical. The website is
http://biad73.uthscsa.edu/
I hope this is useful.
Best wishes,
Narender Ramnani
--
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Dr Narender Ramnani
Sensorimotor Control Group
Department of Physiology
University of Oxford
Parks Road
Oxford OX1 3TP
Oxford University Centre for
Functional Magnetic Resonance Imaging of the Brain,
John Radcliffe Hospital,
Headington,
Oxford OX3 9DU
Tel. 01865 222704 (Direct)
01865 222729 (Admin)
mob. 0771 2632785
Fax. 01865 222717
email [log in to unmask]
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