title: Mapping oxygen concentration in the awake mouse brain.
abstract: Although critical for brain function, the physiological values of cerebral oxygen concentration have remained elusive because high-resolution measurements have only been performed during anesthesia, which affects two major parameters modulating tissue oxygenation: neuronal activity and blood flow. Using measurements of capillary erythrocyte-associated transients, fluctuations of oxygen partial pressure (Po2) associated with individual erythrocytes, to infer Po2 in the nearby neuropil, we report the first non-invasive micron-scale mapping of cerebral Po2 in awake, resting mice. Interstitial Po2 has similar values in the olfactory bulb glomerular layer and the somatosensory cortex, whereas there are large capillary hematocrit and erythrocyte flux differences. Awake tissue Po2 is about half that under isoflurane anesthesia, and within the cortex, vascular and interstitial Po2 values display layer-specific differences which dramatically contrast with those recorded under anesthesia. Our findings emphasize the importance of measuring energy parameters non-invasively in physiological conditions to precisely quantify and model brain metabolism.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.|Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France.
authors.forename: Declan G
authors.identifier: http://orcid.org/0000-0003-1775-4653
authors.initials: DG
authors.lastname: Lyons
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.|Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Parpaleix
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.|Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France.
authors.forename: Morgane
authors.initials: M
authors.lastname: Roche
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1128, Paris, France.|Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Charpak
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D051379:Mice; D010100:Oxygen / Q000032:analysis*; D010313:Partial Pressure
chemical_list: D010100:Oxygen
keywords: blood flow; cortex; human biology; medicine; mouse; neuroscience; olfactory bulb; oxygen; phosphorescence; two-photon microscopy
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