Macroanatomical alignment improves the intersubject consistency of cytoarchitectonic regions in the human ventral stream

Abstract

Eight cytoarchitectonic regions (cROIs) have been identified in the human ventral stream including the primary visual cortex and and higher visual areas (Amunts et al., 2000; Rottschy et al., 2007, Caspers et al., 2013; Lorenz et al., 2015). While hOc1 is consistently located in the calcarine sulcus (Fischl et al., 2008), it is unknown whether such a correspondence between cROIs and anatomical landmarks persists in higher-level regions. We hypothesized that if such a correspondence exists, cortex-based alignment (CBA) of cROIs will yield better consistency across subjects than volume-based alignment. Each of the 8 cROIs was projected to the cortical surface of each subject's brain. We then generated a group map of each cROI by transforming individual subjects' cROIs into a common anatomical space (Figure 1) using three types of alignments: (1) volume-based alignment to the MNI template, (2) CBA to a template cortical surface, either the Freesurfer average brain (CBAfs) or average of the 9 PM brains (CBApm), and (3) CBA with additional constraints of the mid fusiform sulcus and collateral sulcus (CBApm+MFS+CoS). We examined which method produced the most accurate group cROI. Results show that CBAfs and CBApm alignments significantly improve the across-subject correspondence of the 8 cROIs compared to volume alignment (F(2,34) = 31.418, p < .001, Figure 2). Further, adding the MFS and CoS to the alignment significantly reduces inter-subject variability in the location of the FG1/FG2 boundary (p < .05, permutation test, Figure 3) but not the FG3/FG4 boundary compared to both CBA approaches, Overall, these results suggest that CBA generates more accurate atlases of the cytoarchitectonic structure of the ventral stream by preserving the location of cROIs relative to the cortical folding. Further, adding ventral stream sulci as constraints to the CBA improves the accuracy of localizing the boundaries between cROIs

Meeting abstract presented at VSS 2016