title: Broadcasting of cortical activity to the olfactory bulb.
abstract: Odor representations are initially formed in the olfactory bulb, which contains a topographic glomerular map of odor molecular features. The bulb transmits sensory information directly to piriform cortex, where it is encoded by distributed ensembles of pyramidal cells without spatial order. Intriguingly, piriform cortex pyramidal cells project back to the bulb, but the information contained in this feedback projection is unknown. Here, we use imaging in awake mice to directly monitor activity in the presynaptic boutons of cortical feedback fibers. We show that the cortex provides the bulb with a rich array of information for any individual odor and that cortical feedback is dependent on brain state. In contrast to the stereotyped, spatial arrangement of olfactory bulb glomeruli, cortical inputs tuned to different odors commingle and indiscriminately target individual glomerular channels. Thus, the cortex modulates early odor representations by broadcasting sensory information diffusely onto spatially ordered bulbar circuits.
authors.affiliation: Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Boyd
authors.affiliation: Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Hiroyuki K
authors.initials: HK
authors.lastname: Kato
authors.affiliation: Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA; Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA; JST, PRESTO, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Takaki
authors.initials: T
authors.lastname: Komiyama
authors.affiliation: Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA. Electronic address: jisaacson@ucsd.edu.
authors.forename: Jeffry S
authors.initials: JS
authors.lastname: Isaacson
mesh_terms: D000818:Animals; D000840:Anisoles / Q000494:pharmacology; D002525:Cerebellar Cortex / Q000502:physiology*; D003437:Crotonates / Q000494:pharmacology; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects; D045782:Hemiterpenes; D008742:Methyl n-Butyl Ketone / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009812:Odorants; D009830:Olfactory Bulb / Q000187:drug effects / Q000502:physiology*; D061848:Optical Imaging
chemical_list: D000840:Anisoles; D003437:Crotonates; D045782:Hemiterpenes; D008742:Methyl n-Butyl Ketone; C060998:anisole; C009489:tiglic acid