Structure-function spatial covariance in the human visual cortex

The value of sulcal landmarks for predicting functional areas was quantitat ively examined, Medial occipital sulci were identified using anatomical mag netic resonance images to create individual cortical-surface models. Functi onal visual areas were identified using retinotopically organized visual st imuli, and positron emission tomography subtraction imaging with intra-subj ect averaging, Functional areas were assigned labels by placement along the cortical surface from V1. Structure-function spatial covariances between s ulci and functional areas, and spatial covariances among functional areas, were determined by projecting sulcal landmarks and functional areas into a standardized stereotaxic space and computing the 'r' statistics. A function al area was considered to spatially covary with a sulcus or another functio nal area if their geometric centers correlated significantly (P < 0.05) in two or more axes, Statistically significant spatial covariances were found for some, but not all comparisons. The finding of significant spatial covar iances within a standardized stereotaxic space indicates that nine-paramete r spatial normalization does not account for all the predictive value of st ructural or functional locations, and may be improved upon by using selecte d sulcal and functional landmarks. The present findings quantify for the fi rst time the strength of structure-function spatial covariance and comment directly on developmental theories addressing the etiology of structure-fun ction correspondence.