Figure 1.

Properties of spontaneous astrocyte Ca²⁺ signals. (A) Diffraction-limited 920-nm excited two-photon (2P) fluorescence image across a single equatorial plane of a GCaMP6f-expressing astrocyte in an acute mouse brain slice of the barrel cortex. Imaging depth ∼83 μm. Top: morphological overview from the time-average of 120 consecutive frames, taken at 0.5 Hz. Bottom: regions of interest (ROIs) corresponding to the detected Ca²⁺ transients (color for better discrimination) are shown. Overlapping ROIs indicate activity occurring in the same area at different time points. Red, central ROI shows the soma. Scale bar, 10 μm (see Video S1). (B) Black traces represent area size-scaled fluorescence transients of spontaneous Ca²⁺ events (i.e., ΔF/F₀ multiplied by the area of the corresponding ROI) ordered, from top to bottom, according to their distance to soma. See Fig. S2 and Materials and Methods for details on the detection algorithm. Bottom (gray): summed activity over all events in the astrocyte processes is shown. Red trace represents somatic activity. The soma was silent throughout the recording. To see this figure in color, go online.