[The effect of experience on post natal development of the vascularization of the visual cortex]

To report the current state of understanding of the basis of post natal development of microvascularization and the influence of the environment.

Postnatal development of sensory systems occurs in two stages: one genetically predetermined and the other modulated by experience, which is especially important during a so called critical period. Increased demand during this period leads to adaptive changes, particularly vascular changes. The cerebral cortical vascularization is mainly composed of a dense capillary network which extends over the entire cortex and whose density corresponds to the metabolic demand. The development of cortical vascularization starts with perpendicular trunks which branch according to demand and form a cortical capillary network, mediated by factors such as endothelial vascular growth factor (VEGF). Many investigations into the effect of external experience have been done on the visual cortex, both for increase and deprivation.

Post natal development with enriched visual environments induces increased vascular density. Absence of visual experience leads to a reduction in cortical activity which induces reduced neurone and vascular density, together with delay in maduration of the cortical angio architectural pattern. The relation between the neurone population and superficial vascular density is unchanged. These changes appear after the critical period of maximal synatic reorganization.