title: Slit2 activity in the migration of guidepost neurons shapes thalamic projections during development and evolution.
abstract: How brain connectivity has evolved to integrate the mammalian-specific neocortex remains largely unknown. Here, we address how dorsal thalamic axons, which constitute the main input to the neocortex, are directed internally to their evolutionary novel target in mammals, though they follow an external path to other targets in reptiles and birds. Using comparative studies and functional experiments in chick, we show that local species-specific differences in the migration of previously identified "corridor" guidepost neurons control the opening of a mammalian thalamocortical route. Using in vivo and ex vivo experiments in mice, we further demonstrate that the midline repellent Slit2 orients migration of corridor neurons and thereby switches thalamic axons from an external to a mammalian-specific internal path. Our study reveals that subtle differences in the migration of conserved intermediate target neurons trigger large-scale changes in thalamic connectivity, and opens perspectives on Slit functions and the evolution of brain wiring.
authors: Inserm, U1024, 75005 Paris, France.
authors: Franck
authors: F
authors: Bielle
authors: Paula
authors: P
authors: Marcos-Mondejar
authors: Maryama
authors: M
authors: Keita
authors: Caroline
authors: C
authors: Mailhes
authors: Catherine
authors: C
authors: Verney
authors: Kim
authors: K
authors: Nguyen Ba-Charvet
authors: Marc
authors: M
authors: Tessier-Lavigne
authors: Guillermina
authors: G
authors: Lopez-Bendito
authors: Sonia
authors: S
authors: Garel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001369:Axons / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology*; D002540:Cerebral Cortex / Q000196:embryology / Q000378:metabolism*; D002642:Chick Embryo; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009415:Nerve Net / Q000196:embryology / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009434:Neural Pathways / Q000196:embryology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D013045:Species Specificity; D013788:Thalamus / Q000196:embryology / Q000378:metabolism*; D014426:Turtles; D000098552:Slit Homolog 2 Protein
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D000098552:Slit Homolog 2 Protein