Inputs from the thalamocortical system on axon pathfinding mechanisms

Our understanding of axon pathfinding mechanisms has dramatically advanced thanks to the identification of guidance cues and receptors, and has been forged by the study of a limited number of model systems. Thalamocortical axons, which are essential for sensory processing and neocortical functioning, convey sensory information to the neocortex through a tightly controlled topographical interconnectivity between distinct thalamic neurons and cortical areas. Recent studies on this projection have provided mechanistic insights onto integrated processes controlling brain wiring: axons/guidepost cells interactions, building of reciprocal connections and the combinatorial activity of guidance cues. This review provides a selective overview of these novel features and stresses the interest of thalamocortical axons as an emerging model for studying axonal guidance and plasticity.