Topographic guidance labels in a sensory projection to the forebrain.
Visual connections to the mammalian forebrain are known to be patterned by neural activity, but it remains unknown whether the map topography of such higher sensory projections depends on axon guidance labels. Here, we show complementary expression and binding for the receptor EphA5 in mouse retina and its ligands ephrin-A2 and ephrin-A5 in multiple retinal targets, including the major forebrain target, the dorsal lateral geniculate nucleus (dLGN). These ligands can act in vitro as topographically specific repellents for mammalian retinal axons and are necessary for normal dLGN mapping in vivo. The results suggest a general and economic modular mechanism for brain mapping whereby a projecting field is mapped onto multiple targets by repeated use of the same labels. They also indicate the nature of a coordinate system for the mapping of sensory connections to the forebrain.
Feldheim
D A
DA
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Vanderhaeghen
P
P
Hansen
M J
MJ
Frisén
J
J
Lu
Q
Q
Barbacid
M
M
Flanagan
J G
JG
D000375:Aging / Q000502:physiology; D000818:Animals; D001369:Axons / Q000502:physiology*; D001931:Brain Mapping; D004622:Embryo, Mammalian; D036383:Ephrin-A2; D036386:Ephrin-A5; D018507:Gene Expression Regulation, Developmental; D005829:Geniculate Bodies / Q000502:physiology; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics*; D051379:Mice; D016133:Polymerase Chain Reaction; D016548:Prosencephalon / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis / Q000235:genetics*; D036123:Receptor, EphA5; D012160:Retina / Q000502:physiology*; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*; D014795:Visual Pathways / Q000196:embryology / Q000254:growth & development / Q000502:physiology*
D036383:Ephrin-A2; D036386:Ephrin-A5; D008565:Membrane Proteins; D014157:Transcription Factors; D020794:Receptor Protein-Tyrosine Kinases; D036123:Receptor, EphA5