Fig. 2

Spontaneous astrocytic Ca²⁺ events are fully autonomous and partly depend on external Ca²⁺ entry. a, b Within the astrocytic population, proportion of astrocytes displaying calcium activity and frequency of astrocyte calcium activity in physiological condition (grey; n = 43), under 500 nM TTX application (dark blue; n = 6) or in Ca²⁺-free medium (0 Ca; light blue; n = 9). Each dot corresponds to individual value for each recorded slice (proportion) or each recorded ROI (frequency). c Frequency histogram revealing that 500 nM TTX had no effect on the frequency distribution whereas significantly less astrocytes were hyperactive in Ca²⁺-free medium (0 Ca²⁺; light blue). d, e Within single astrocyte arbor, proportion of subregions displaying calcium activity and frequency of astrocyte calcium activity in physiological condition (grey; n = 7), under 500 nM TTX application (dark blue; n = 7) or in Ca²⁺-free medium (0 Ca²⁺; light blue; n = 7). Each dot corresponds to individual value for each recorded astrocyte (proportion) or each recorded ROI (frequency). Results are compared with the physiological condition with *, p < 0.05; **, p < 0.01 and ***, p < 0.001