The adult brain emerges from an interplay between a domain-general map-based architecture, shaped by intrinsic mechanisms, and experience. Our lab investigates these processes across species using neuroimaging, electrophysiology, and behavioral methods to understand how visual system organization arises and supports perception.
Topographic maps are the fundamental organizing principle of the visual brain. Retinotopic organization pervades not only visual cortex but also subcortical structures like the pulvinar, challenging traditional cortico-centric models of vision. Using naturalistic stimuli, we've identified pulvinar regions selective for faces and bodies that are co-active with corresponding cortical areas during natural scene viewing, demonstrating that principles of cortical organization, including functional clustering and hierarchical structure, also manifest in subcortex. Functional domains emerge within this map-based architecture, and these domains are architectonically distinct, with face-selective patches showing unique microstructural properties. This universal topographic organization provides a framework for understanding how the brain processes information and establishes functional homologies across primate species.
What is innate and what is learned? Our work has shown that the newborn primate brain already contains a sophisticated visual architecture with multiple processing pathways, hierarchical structure, and thalamocortical connectivity in place at birth. The tripartite organization of dorsal, lateral, and ventral pathways—extending from early visual cortex through higher-order regions—is already established in neonates, as is the hierarchical, retinotopic connectivity between the pulvinar and cortex. However, these pathways show differential maturity: dorsal areas are near adult-like while ventral areas remain poised for experience-dependent refinement. This "domain-relevant" organization provides scaffolding for subsequent specialization, where experience shapes a general architecture into the specialized domains characteristic of adult vision.
What makes the human visual brain unique? Our comparative work has revealed that human visual cortex expansion is driven by enlargement of a conserved map architecture present in other primates, rather than the addition of novel areas. Expansion is most pronounced in parietal and higher-order temporal regions, and this is already established prenatally in both species. More broadler, humans exhibit a markedly prolonged developmental trajectory. While cortex in both species exhibit an inside-out pattern of maturation from deeper to superficial, human cortical matruation extends over a much longer period with greater depth-dependent differences across the hierarchy. This extended window of plasticity, particularly in later-maturing superficial layers, may provide the substrate for the experience-dependent refinement that supports our advanced perceptual and cognitive abilities.
