The complex interplay between structure and function in the brain

The brain is a highly structured network, and its characteristic functional organization is thought to subtend perception. A paradigmatic example is given by the visual cortex: imaging techniques have shown the very specific structure of orientation selectivity made of continuous regions interspersed with discrete singularities with pinwheel organization. We will show that a similar structure, with dipolar singularities, appears in the cells selectivity to spatial frequency. Surprisingly, comparing both singularities reveal their possible topological optimality and the role they may play for perception. While these structures are refined with visual experience at late stages of development, an important part of it develops early independently of any visual experience. The structuring program is thus contained in the interaction of developmental genes and their products, that have very specific properties: they are their own promotor, and are endowed with very local non cell-autonomous properties. We will investigate the possible role of these specificities in the formation of cortical areas of reliable shapes.