title: Glomerular and Mitral-Granule Cell Microcircuits Coordinate Temporal and Spatial Information Processing in the Olfactory Bulb.
abstract: The olfactory bulb processes inputs from olfactory receptor neurons (ORNs) through two levels: the glomerular layer at the site of input, and the granule cell level at the site of output to the olfactory cortex. The sequence of action of these two levels has not yet been examined. We analyze this issue using a novel computational framework that is scaled up, in three-dimensions (3D), with realistic representations of the interactions between layers, activated by simulated natural odors, and constrained by experimental and theoretical analyses. We suggest that the postulated functions of glomerular circuits have as their primary role transforming a complex and disorganized input into a contrast-enhanced and normalized representation, but cannot provide for synchronization of the distributed glomerular outputs. By contrast, at the granule cell layer, the dendrodendritic interactions mediate temporal decorrelation, which we show is dependent on the preceding contrast enhancement by the glomerular layer. The results provide the first insights into the successive operations in the olfactory bulb, and demonstrate the significance of the modular organization around glomeruli. This layered organization is especially important for natural odor inputs, because they activate many overlapping glomeruli.
authors.affiliation: Department of Neuroscience, School of Medicine, Yale UniversityNew Haven, CT, USA; Department of Mathematics "Federigo Enriques", University of MilanMilan, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cavarretta
authors.affiliation: Department of Mathematics and Application "R. Cacciopoli", University of Naples Federico II Naples, Italy.
authors.forename: Addolorata
authors.initials: A
authors.lastname: Marasco
authors.affiliation: Department of Neuroscience, School of Medicine, Yale University New Haven, CT, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Hines
authors.affiliation: Department of Neuroscience, School of Medicine, Yale University New Haven, CT, USA.
authors.forename: Gordon M
authors.initials: GM
authors.lastname: Shepherd
authors.affiliation: Department of Neuroscience, School of Medicine, Yale UniversityNew Haven, CT, USA; Institute of Biophysics, National Research CouncilPalermo, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Migliore
keywords: glomerulus; granule; mitral; natural odor; odor learning; olfactory bulb; periglomerular