title: Integrating temperature with odor processing in the olfactory bulb.
abstract: Temperature perception has long been classified as a somesthetic function solely. However, in recent years several studies brought evidence that temperature perception also takes place in the olfactory system of rodents. Temperature has been described as an effective stimulus for sensory neurons of the Grueneberg ganglion located at the entrance of the nose. Here, we investigate whether a neuronal trace of temperature stimulation can be observed in the glomeruli and mitral cells of the olfactory bulb, using calcium imaging and fast line-scanning microscopy. We show in the Xenopus tadpole system that the γ-glomerulus, which receives input from olfactory neurons, is highly sensitive to temperature drops at the olfactory epithelium. We observed that thermo-induced activity in the γ-glomerulus is conveyed to the mitral cells innervating this specific neuropil. Surprisingly, a substantial number of thermosensitive mitral cells were also chemosensitive. Moreover, we report another unique feature of the γ-glomerulus: it receives ipsilateral and contralateral afferents. The latter fibers pass through the contralateral bulb, cross the anterior commissure, and then run to the ipsilateral olfactory bulb, where they target the γ-glomerulus. Temperature drops at the contralateral olfactory epithelium also induced responses in the γ-glomerulus and in mitral cells. Temperature thus appears to be a relevant physiological input to the Xenopus olfactory system. Each olfactory bulb integrates and codes temperature signals originating from receptor neurons of the ipsilateral and contralateral nasal cavities. Finally, temperature and chemical information is processed in shared cellular networks.
authors.affiliation: Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, 37073 Göttingen, Germany, Bernstein Center for Computational Neuroscience, 37073 Göttingen, Germany.
authors.forename: Eugen
authors.initials: E
authors.lastname: Kludt
authors.affiliation: Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, 37073 Göttingen, Germany, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Georg-August-Universität Göttingen, 37073 Göttingen, Germany.
authors.forename: Camille
authors.initials: C
authors.lastname: Okom
authors.affiliation: Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, 37073 Göttingen, Germany, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Georg-August-Universität Göttingen, 37073 Göttingen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Brinkmann
authors.affiliation: Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, 37073 Göttingen, Germany, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Georg-August-Universität Göttingen, 37073 Göttingen, Germany, DFG Excellence Cluster 171, University of Göttingen, 37073 Göttingen, Germany, and Bernstein Center for Computational Neuroscience, 37073 Göttingen, Germany dschild@gwdg.de.
authors.forename: Detlev
authors.initials: D
authors.lastname: Schild
mesh_terms: D000818:Animals; D002628:Chemoreceptor Cells / Q000502:physiology; D005260:Female; D007814:Larva / Q000502:physiology; D008297:Male; D009830:Olfactory Bulb / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D012903:Smell; D013823:Thermoreceptors / Q000502:physiology; D013697:Thermosensing; D014981:Xenopus
keywords: activity correlation imaging; chemosensitivity; integration; mitral cells; olfactory bulb; thermosensitivity