title: Circuit formation and function in the olfactory bulb of mice with reduced spontaneous afferent activity.
abstract: The type of neuronal activity required for circuit development is a matter of significant debate. We addressed this issue by analyzing the topographic organization of the olfactory bulb in transgenic mice engineered to have very little afferent spontaneous activity due to the overexpression of the inwardly rectifying potassium channel Kir2.1 in the olfactory sensory neurons (Kir2.1 mice). In these conditions, the topography of the olfactory bulb was unrefined. Odor-evoked responses were readily recorded in glomeruli with reduced spontaneous afferent activity, although the functional maps were coarser than in controls and contributed to altered olfactory discrimination behavior. In addition, overexpression of Kir2.1 in adults induced a regression of the already refined connectivity to an immature (i.e., coarser) status. Our data suggest that spontaneous activity plays a critical role not only in the development but also in the maintenance of the topography of the olfactory bulb and in sensory information processing.
authors.affiliation: Venetian Institute of Molecular Medicine (VIMM), 35129 Padua, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Lorenzon
authors.affiliation: Venetian Institute of Molecular Medicine (VIMM), 35129 Padua, Italy.
authors.forename: Nelly
authors.initials: N
authors.lastname: Redolfi
authors.affiliation: Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Podolsky
authors.affiliation: Venetian Institute of Molecular Medicine (VIMM), 35129 Padua, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Zamparo
authors.affiliation: Venetian Institute of Molecular Medicine (VIMM), 35129 Padua, Italy.
authors.forename: Sira Angela
authors.initials: SA
authors.lastname: Franchi
authors.affiliation: Neurobiology Group, SISSA, International School for Advanced Studies, 34136 Trieste, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Pietra
authors.affiliation: Biophysics Institute, CNR, 16149 Genova, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Boccaccio
authors.affiliation: Neurobiology Group, SISSA, International School for Advanced Studies, 34136 Trieste, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Menini
authors.affiliation: Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, and.
authors.forename: Venkatesh N
authors.initials: VN
authors.lastname: Murthy
authors.affiliation: Venetian Institute of Molecular Medicine (VIMM), 35129 Padua, Italy, Neuroscience Institute, CNR, 35129 Padua, Italy claudia.lodovichi@unipd.it.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lodovichi
mesh_terms: D000344:Afferent Pathways / Q000737:chemistry / Q000502:physiology; D000818:Animals; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009415:Nerve Net / Q000737:chemistry / Q000502:physiology*; D009812:Odorants; D009830:Olfactory Bulb / Q000737:chemistry / Q000502:physiology*; D009833:Olfactory Pathways / Q000737:chemistry / Q000502:physiology*; D018035:Receptors, Odorant / Q000032:analysis / Q000502:physiology
chemical_list: D018035:Receptors, Odorant
keywords: behavior; functional imaging; olfactory bulb; olfactory system; sensory map; topography