Cortical gradients of functional integration
Historically, cognitive neuroscience has focused on discrete, mutually exclusive modules or networks, however, current network-level descriptions of brain organization fail to account for integrated features of cognition. I recently described a principal gradient in cortical connectivity that reflects how activity from primary sensory/motor areas is integrated into transmodal regions of the default-mode network. This novel line of research led me to hypothesize that coherent aspects of cognition are an emergent property of a whole brain architecture consisting of multiple zones of integration. In particular, I hypothesize that each region of transmodal cortex is the apex of a zone of integration that is anchored by multiple unimodal cortical regions. To investigate the mechanism that allows abstract representations to form in transmodal systems, I first propose structural studies to investigate covariance in zone geometry across healthy adults, how zones have emerged through evolution and how they change across the lifespan. I will then explore the functional consequence of zones of integration for higher-order human cognition. I will examine if individual differences in cognition emerges from variation in the architecture of different zones, and how brain activity is altered when simple decisions depend on integrating information from multiple zones. Finally, I will examine how the absence of input from a sensory modality (through congenital deafness or blindness) alters the structure and function of transmodal regions in a zone-specific manner. By describing how the spatial layout of the cortex shapes its functions, this research provides a radically new framework for understanding the structural constraints that underpin the integrated nature of human cognition.