Brodmann areas are histologically defined. It is hence, by definition, impossible - at least with current in vivo imaging - to derive them directly from imaging. Most so-called "Brodmann maps" are crude approximations translating some aspect of Brodmann's original research onto 2D atlases (Talairach) and onwards from there (e.g. WFU Pickatlas). I'm not sure where the MRIcroN "Brodmann map" comes from, but inconsistencies are to be expected, rather than to be surprised about.
I would suggest the following ways forward:
1) Forget Brodmann areas and label your activations in an individual with what you can actually see, that is to say accepted anatomical nomenclature for gyri and sulci in individuals derived from their own anatomical imaging. (At the same time, you may wish to ditch the nonsensical term "pre"frontal ;-) ).
2) If you must, only use Brodmann maps actually derived from histology. The Jülich group has been involved in a multi-year effort of deriving probabilistic histology maps in MNI space - see the work by Zilles K, Amunts K, Eickhoff S et al.
3) For group studies, and when no Jülich or other histology-based maps are available, use anatomical terms based on anatomy visible in your template (normally MNI) or, if you're unsure, anatomical terms based on multi-subject atlases - those will avoid you running into the same trouble again. One option is our maximum probability map containing 83 regions based on 30 subjects (Hammers A, Allom R et al. 2003; Gousias IS et al. 2008); contact me for a free one-page academic licence if you're interested.
In any case, you have re-discovered the need to fully describe your methodology, including exactly which spatial normalisation steps were taken in order to normalise to which template, and how anatomical allocation was performed... see "Ten simple rules <...>" by Ridgway GR et al. 2008, Brett M et al. Nat Rev Neurosci 2002, Devlin JT and Poldrack RA 2007, our work, etc.
All the best,
Alexander Hammers, MD PhD
Chair in Functional Neuroimaging
CERMEP – Imagerie du Vivant
Hôpital Neurologique Pierre Wertheimer
59 Boulevard Pinel, 69003 Lyon, France
Telephone +33-(0)4-72 68 86 34
Fax +33-(0)4-72 68 86 10
Email [log in to unmask];[log in to unmask]
Visiting Reader; Honorary Consultant Neurologist
Division of Neuroscience and Mental Health, Faculty of Medicine
Imperial College London, UK
Honorary Reader in Neurology; Honorary Consultant Neurologist
Department of Clinical and Experimental Epilepsy
National Hospital for Neurology and Neurosurgery/ Institute of Neurology, University College London, UK
On 12 Aug 2011, at 13:10, Christian Baeuchl wrote:
> Dear experts,
> in one experiment we found a right lateral prefrontal activation cluster (MNI coordinates of strongest activated voxel: x=47, y=48, z=-3) which is mainly attributed to Brodmann area 10 (BA 10) if we look at the BA 10 ROI-mask derived from WFU Pickatlas, but lies entirely in BA 46 and BA 47 if we project the activation cluster onto the Brodmann map implemented in MRIcron.
> The Talairach Client also attributes voxels from that cluster to BA 10 and BA 46. We are confused about which Brodmann area maps we should “trust” and also about the very fact that they differ so greatly from each other (shouldn’t they all be same?).
> I’ve attached two files: the first showing how the BA 10 mask (in bright red) from WFU Pickatlas overlaps with BA 46(in green) and other areas when projected onto the MRIcron Brodmann template; the other displays the position of the activated prefrontal region in our experiment.
> Any help on this would be much appreciated,
> <BA-MRIcron_overlayBA10(wfu).pdf><prefrontal activation.pdf>