Figure 4.

Robust spontaneous transients are observed in astrocytic somas and processes in hippocampal organotypic slice cultures. (A) Example mean calcium activity projection image of astrocytes expressing Lck-GCaMP6f in a hippocampal organotypic slice culture. ROIs are denoted by dashed circles including three adjacent somas. (B) ΔF/F₀ traces of ROIs shown in (A). Line colors in (B) correspond to ROI colors in (A). Inverted blue arrows mark peaks that reached threshold and were included as events for analysis. “Merged” events, which encompass two proximate peaks, were counted as a single long event (see dark pink and dark green ROIs). (C) A cumulative histogram displaying the relative frequency (event counts normalized by total events in each structure) of spontaneous event peak ΔF/F₀ values. The number of total events in each structure is shown in parentheses next to the structure name. (D) A cumulative histogram displaying spontaneous event duration. Soma data is shown in orange and process data in blue. The distribution of each measurement was compared between somas and processes. The calculated p-value from a Kolmogorov–Smirnov test is shown in the plot. Red text denotes significance and black text denotes no significance detected at a level of p < 0.05. (E) Example mean calcium activity projection of a neuron expressing Lck-GCaMP6f. (F) ΔF/F₀ traces corresponding to ROIs shown in (E).