Abstract
Characterizing the functional organization of visual cortex is a fundamental step in understanding how visual information is processed in the brain. Despite a century's effort to map visual cortical areas, there has been no comprehensive parcellation scheme for the entire visual cortex in the human brain. Here we used functional MRI and developed a data-driven approach to cluster occipito-temporal vertices of the cortical surface based on their responses to a 90-minute natural movie stimulus. To achieve an optimal clustering, the vertices were first represented in a lower-dimensional space using the principal component analysis (PCA), then a hierarchical clustering was applied in the PCA space. The hierarchical clustering enabled us to evaluate the macro-organization of visual cortex at different spatial scales. In all levels of hierarchical clustering, the functionally-defined clusters were remarkably organized on the cortical surface. In addition to all previously-known category-selective areas, the clustering revealed many spatially-localized regions in the occipito-temporal cortex. We characterized one specific region in the lateral temporal cortex ('area LT') that was selectively activated by object motion or body action in the movie. The cortical parcellation scheme presented here could guide subsequent studies in defining the functional properties of many new cortical areas.
Meeting abstract presented at VSS 2014