Brain structure shapes cognitive functions and constrains behaviors, but varies remarkably across human individuals even for the earliest sensory cortices. To understand the topographic principles of such cortical variability, we investigated whether the volume of functionally defined primary visual cortex predicted that of other cortical structures. In a large sample of healthy participants, the gray matter volume of primary visual cortex correlated positively with that of primary auditory cortex, but negatively with focal areas of anterior prefrontal cortex. These structural relationships were specific to primary visual cortex (V1) and not observed for associated visual cortices V2 or V3. Moreover, the retinotopically ventral (representing the upper visual field map) and dorsal (representing the lower visual field map) halves of V1 shared variation with the corresponding but not the opposite halves of V2, V3, and exhibited focal negative correlations with ventromedial and dorsolateral areas of anterior prefrontal cortex respectively. Our study revealed a structural trade-off between primary sensory and prefrontal cortices that arises from two separated anatomical pathways. This intriguing and hitherto unknown topographical organization of human cortex is likely to be regulated by genetic or developmental mechanisms and may be the basis of inter-individual behavioral differences in basic sensory versus high-order cognitive processing.
This work was supported by the Brain Research Trust (CS), JSPS (RK) and the Wellcome Trust (GR, DSS).