Figure 5. Cortical astrocyte Ca²⁺ dynamics exhibit bidirectional changes preceding sleep and wake transitions.

(A) Within each individual sleep/wake period, the proportion of all astrocyte Ca²⁺ events increases before transitions to wake (red) and decreases before transitions to sleep (blue). Error bars=SEM. (B) In contrast, the proportion of all Ca²⁺ events in a sleep or wake period in IP₃R2 KO mice does not consistently change preceding transitions. Error bars=SEM. (C) Example filtered LFP (0.5–4 Hz) trace across sleep (NREM) and wake transitions. All sleep (red) and wake (blue) periods were divided in three equal bins to examine Ca²⁺ dynamics across individual behavioral states. (D) Change in Ca²⁺ event number across sleep and wake periods show an increase in event number in the last third of sleep (left) and a decrease in the last third of wake (right) (paired t-test). Change in Ca²⁺ event number across sleep periods (left) increases in the last third for control, but not IP₃R2 KO mice (unpaired t-test). Data are represented as mean± SEM (controls: n = 4 mice, 19 hr; IP₃R2 KO = 5 mice, 22 hr).