title: Rapid astrocyte calcium signals correlate with neuronal activity and onset of the hemodynamic response in vivo.
abstract: Elevation of intracellular Ca2+ in astrocytes can influence cerebral microcirculation and modulate synaptic transmission. Recently, in vivo imaging studies identified delayed, sensory-driven Ca2+ oscillations in cortical astrocytes; however, the long latencies of these Ca2+ signals raises questions in regards to their suitability for a role in short-latency modulation of cerebral microcirculation or rapid astrocyte-to-neuron communication. Here, using in vivo two-photon Ca2+ imaging, we demonstrate that approximately 5% of sulforhodamine 101-labeled astrocytes in the hindlimb area of the mouse primary somatosensory cortex exhibit short-latency (peak amplitude approximately 0.5 s after stimulus onset), contralateral hindlimb-selective sensory-evoked Ca2+ signals that operate on a time scale similar to neuronal activity and correlate with the onset of the hemodynamic response as measured by intrinsic signal imaging. The kinetics of astrocyte Ca2+ transients were similar in rise and decay times to postsynaptic neuronal transients, but decayed more slowly than neuropil Ca2+ transients that presumably reflect presynaptic transients. These in vivo findings suggest that astrocytes can respond to sensory activity in a selective manner and process information on a subsecond time scale, enabling them to potentially form an active partnership with neurons for rapid regulation of microvascular tone and neuron-astrocyte network properties.
authors.affiliation: Department of Psychiatry, Brain Research Center, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Winship
authors.forename: Nathan
authors.initials: N
authors.lastname: Plaa
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Murphy
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001253:Astrocytes / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D005260:Female; D006614:Hindlimb / Q000098:blood supply; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D013003:Somatosensory Cortex / Q000098:blood supply* / Q000502:physiology*; D013997:Time Factors