title: Sensory map transfer to the neocortex relies on pretarget ordering of thalamic axons.
abstract: Sensory maps, such as the representation of mouse facial whiskers, are conveyed throughout the nervous system by topographic axonal projections that preserve neighboring relationships between adjacent neurons. In particular, the map transfer to the neocortex is ensured by thalamocortical axons (TCAs), whose terminals are topographically organized in response to intrinsic cortical signals. However, TCAs already show a topographic order early in development, as they navigate toward their target. Here, we show that this preordering of TCAs is required for the transfer of the whisker map to the neocortex. Using Ebf1 conditional inactivation that specifically perturbs the development of an intermediate target, the basal ganglia, we scrambled TCA topography en route to the neocortex without affecting the thalamus or neocortex. Notably, embryonic somatosensory TCAs were shifted toward the visual cortex and showed a substantial intermixing along their trajectory. Somatosensory TCAs rewired postnatally to reach the somatosensory cortex but failed to form a topographic anatomical or functional map. Our study reveals that sensory map transfer relies not only on positional information in the projecting and target structures but also on preordering of axons along their trajectory, thereby opening novel perspectives on brain wiring.
authors.affiliation: Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), 46 Rue d'Ulm, 75005 Paris, France.
authors.forename: Ludmilla
authors.initials: L
authors.lastname: Lokmane
authors.forename: Rémi
authors.initials: R
authors.lastname: Proville
authors.forename: Nicolas
authors.initials: N
authors.lastname: Narboux-Nême
authors.forename: Ildiko
authors.initials: I
authors.lastname: Györy
authors.forename: Maryama
authors.initials: M
authors.lastname: Keita
authors.forename: Caroline
authors.initials: C
authors.lastname: Mailhes
authors.forename: Clément
authors.initials: C
authors.lastname: Léna
authors.forename: Patricia
authors.initials: P
authors.lastname: Gaspar
authors.forename: Rudolf
authors.initials: R
authors.lastname: Grosschedl
authors.forename: Sonia
authors.initials: S
authors.lastname: Garel
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D001931:Brain Mapping; D051379:Mice; D019579:Neocortex / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D013788:Thalamus / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014738:Vibrissae / Q000166:cytology / Q000196:embryology* / Q000378:metabolism
chemical_list: C489921:Ebf1 protein, mouse; D015534:Trans-Activators