Extended Data Fig. 8: Centripetal propagation can be variable across different putative single astrocytic domains.
From: Centripetal integration of past events in hippocampal astrocytes regulated by locus coeruleus
Manual seeding of the astrocyte cell body centroid with subsequent watershed segmentation was used to create putative astrocytic domains (cell bodies identified based on average fluorescence in (a), segmented domains with ID numbers in (b)). For each domain, the delay map (c) was used to extract delayed traces as shown in Fig. 6a–c, and a slope was fitted to the delayed traces for each detected event and each astrocytic domain, as described in Fig. 6c. Positive slope (blue) indicates an event propagating into the somatic region of the respective domain, a negative slope (red) indicates a fading event (d). Overlaid traces display the average activity in the respective domain. e, Similarity of slopes across events for pairs of astrocytic domains quantified as correlation. The distribution is centered on positive values, showing that most astrocytic domains follow the propagation/fading of the majority of other domains. f, Distance dependence of the pair-wise correlations of propagation slopes from e, indicating a weak decay of the correlation with distance. However, low correlations occur also at neighboring domains (distance approx. 20–50 µm), and high correlations at large distances. g, Centripetal propagation appears more prominent in some astrocytic domains for some events. Zoom-in #1 from d into a subset of events (event numbers in Roman numerals below) and astrocytic domains (numbers on the right side). In addition, delayed traces are shown (color-coding as in Fig. 6; from yellow = distal processes, to blue = astrocytic soma). In some domains, the somatic trace is activated much more than for other domains (for example, domain 15) or for other events in other domains (for example, domain 18 for event II, domain 20 for event IV, and domain 23 for event IV). This observation indicates that the strength of somatic activation by centripetal propagation is variable across astrocytes. h, Zoom-in #2 from d, manually re-ordered selection of traces (numbers to the right indicate the putative astrocytic domain). The first event is the event of interest for the purpose of this panel. While the event is globally dominated by fading calcium signals as seen in d, calcium activity in some domains clearly reaches the somatic regions (astrocytic domain IDs 30, 38 and 6). This observation suggests that centripetal propagation is a cell-autonomous process that can occur in a subset of astrocytes.
