Rapid stimulus-evoked astrocyte Ca2+ elevations and hemodynamic responses in mouse somatosensory cortex in vivo

changes in astrocyte activity are rapid and widespread enough to contribute to brain blood flow control. Here, we provide evidence for stimulus-evoked Ca2+ elevations with rapid onset and short duration in a large proportion of cortical astrocytes in the adult mouse somatosensory cortex. Our improved detection of the fast Ca2+ signals is due to a signal-enhancing analysis of the Ca2+ activity. The rapid stimulation-evoked Ca2+ increases identified in astrocyte somas, processes, and end-feet preceded local vasodilatation. Fast Ca2+ responses in both neurons and astrocytes correlated with synaptic activity, but only the astrocytic responses correlated with the hemodynamic shifts. These data establish that a large proportion of cortical astrocytes have brief Ca2+ responses with a rapid onset in vivo, fast enough to initiate hemodynamic responses or influence synaptic activity.