Neural ECM in laminar organization and connectivity development in healthy and diseased human brain

The neural extracellular matrix (ECM) provides a supportive framework for differentiating cells and their processes and regulates morphogenetic events by spatially and temporally relevant localization of signaling molecules and by direct signaling via receptor and/or coreceptor-mediated action. The embryonic human brain and fetal human brain contain large amounts and a diversity of extracellular matrix components, which are especially prominent in the transient subplate zone, in the crossroads of axonal pathways, at the developing cortical-white matter interface, and in the marginal zone. Perinatal and postnatal reorganizations of these tissue compartments extend into the second year of life. Developmental changes in the amount and composition of the extracellular matrix (as well as changes in fiber architectonics) are significant for plastic responses to damage and for changes in magnetic resonance imaging (MRI) signal intensity of the fetal and early postnatal human brain. In this chapter, we discuss the expression pattern of the major components of the fetal ECM of the human brain and the role they play during laminar and connectivity development in healthy brain and in the neurodevelopmental disorders. The aim of the chapter is to elucidate ECM-related developmental events as potential models of successful functional recovery after injury and to explore its relevance for diagnostic and therapeutic approaches.