Consequences of large interindividual variability for human brain atlases: converging macroscopical imaging and microscopical neuroanatomy

Abstract

In human brain imaging studies, it is common practice to use the Talairach stereotaxic reference system for signifying the convergence of brain function and structure. In nearly all neuroimaging reports, the studied cortical areas are specified further with a Brodmann Area (BA) number. This specification is based upon macroscopic extrapolation from Brodmann's projection maps into the Talairach atlas rather than upon a real microscopic cytoarchitectonic study. In this review we argue that such a specification of Brodmann area(s) via the Talairach atlas is not appropriate. Cytoarchitectonic studies reviewed in this paper show large interindividual differences in 3-D location of primary sensory cortical areas (visual cortex) as well as heteromodal associational areas (prefrontal cortical areas), even after correction for differences in brain size and shape. Thus, the simple use of Brodmann cortical areas derived from the Talairach atlas can lead to erroneous results in the specification of pertinent BA. This in turn can further lead to wrong hypotheses on brain system(s) involved in normal functions or in specific brain disorders. In addition, we will briefly discuss the different 'Brodmann' nomenclatures which are in use for the cerebral cortex.

Differences in genetic and environmental influences on the human cerebral cortex associated with development during childhood and adolescence

“…A limitation common to current structural neuroimaging techniques is that the location of specific cytoarchitecturally unique regions is estimated based on sulcal and gyral landmarks. It has been shown that the actual placement of Brodmann's areas with respect to cortical topological landmarks shows only partial overlap between individuals [Uylings et al, 2005]. This implies that when brain MRIs are coregistered to a common template using surface topology, the alignment of cytoarchitecturally similar regions between individuals is necessarily incomplete, and consequently that heritability values for cortical thickness also reflect variation in the location of the boundaries of these regions.…”

Defining functional areas in individual human brains using resting functional connectivity MRI

“…The most advanced registration methods available attempt to compensate for individual variation in brain surface shape, size, and folding pattern (Lyttelton et al, 2007;Van Essen, 2005;Van Essen and Dierker, 2007). However, this approach does not provide an ideal solution because the location and extent of each functional area varies substantially from person to person, irrespective of anatomical landmarks (Amunts et al, 2000;Amunts et al, 1999;Andrews et al, 1997;Uylings et al, 2005;Van Essen et al, 1984). Our current work is performed on a within subject basis, but future across subject comparisons will be made through the PALS B12 atlas (Van Essen and Dierker, 2007) using CARET which can account for more individual differences than volumetric averaging.…”

Contrasting functional imaging parametric maps: The mislocation problem and alternative solutions

“…Withinsubject activation maps obtained with fMRI or PET are characterized by point-spread functions of less than 5-mm FWHM. The smoothness of group-averaged maps is however higher due to unavoidable variability in brain structural and functional anatomy (Steinmetz and Seitz, 1991;Uylings et al, 2005). Moreover, for group analyses, maps are often smoothed with Gaussian kernels of 5-15 mm FWHM.…”