Improved correspondence of fMRI visual field localizer data after macroanatomical alignment

Abstract

ABSTRACTThe study of the visual system and its role for human cognition with fMRI often requires the use of localizer paradigms to define regions of interest (ROIs). However, the considerable degree of interindividual variability of the cerebral cortex represents an important confound, when analyzing data on the group level. Cortex-based alignment (CBA) techniques lead to a reliable reduction of interindividual macroanatomical variability. Yet, CBA has not been evaluated for visual field localizer paradigms used to map specific parts of the visual field within retinotopically organized early visual areas. We evaluated CBA for an attention-enhanced visual field localizer mapping a homologous part of each visual quadrant in 50 participants. After CBA, group ROIs showed markedly increased spatial consistency. CBA also led to an increase in the probability of activation overlap of up to forty percent. Furthermore, after CBA group ROI size for the lower visual hemifield was larger than for the upper. This asymmetry, which mirrors previous mapping studies, was not detectable before CBA. Our results confirm and extend the utility of CBA for the study of the visual system in the context of group analyses. CBA should be particularly relevant when studying neuropsychiatric disorders with abnormally increased interindividual macroanatomical variability.