title: Positional information in neural map development: lessons from the olfactory system.
abstract: Positional information is fundamental in development. Although molecular gradients are thought to represent positional information in various systems, the molecular logic used to interpret these gradients remains controversial. In the nervous system, sensory maps are formed in the brain based on gradients of axon guidance molecules. However, it remains unclear how axons find their targets based on relative, not absolute, expression levels of axon guidance receptors. No model solely based on axon-target interactions explains this point. Recent studies in the olfactory system suggested that the neural map formation requires axon-axon interactions, which is known as axon sorting. This review discusses how axon-axon and axon-target interactions interpret molecular gradients and determine the axonal projection sites in neural map formation.
authors.affiliation: Laboratory for Sensory Circuit Formation, RIKEN Center for Developmental Biology, Kobe 650-0047 PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan. imai@cdb.riken.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Imai
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D001931:Brain Mapping; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D008959:Models, Neurological; D039942:Neuropilin-1 / Q000378:metabolism; D009833:Olfactory Pathways / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000166:cytology / Q000502:physiology*; D017729:Presynaptic Terminals / Q000502:physiology; D021382:Protein Sorting Signals; D040121:Semaphorin-3A / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D021382:Protein Sorting Signals; C488217:Sema3a protein, mouse; D040121:Semaphorin-3A; D039942:Neuropilin-1