Fig. 3.

Two-channel recording of the evoked and intrinsic astrocytic Ca²⁺ signal in FP-S1 and barrel cortex (BC). (A) The time courses of the evoked astrocytic Ca²⁺ signal and the fMRI signal from FP-S1 (Left) upon forepaw stimulation (3 Hz, 4 s, 1.5 mA), and the concurrent intrinsic astrocytic Ca²⁺ signal from BC and the fMRI signal from the entire cortex except FP-S1 (Right). (B) The correlation map of the fMRI signal with the intrinsic astrocytic Ca²⁺ spikes detected in BC shows negative correlation across the entire cortex except FP-S1. (C) The amplitude of the astrocytic Ca²⁺ signal (evoked-only) is significantly lower than that of the concurrent events in FP-S1 (Left, *P = 2.0e-15), but the fMRI signal change is significant lower in the concurrent events (Center, &P = 0.026). The fMRI signal in the entire cortex except FP-S1 shows negative amplitude of the concurrent events, which is significantly lower than the evoked-only events (Right, #P = 2.8e-07; evoked-only, trial # = 81; concurrent, trial # = 50, rats, n = 7). (D) The representative traces of astrocytic Ca²⁺ and corresponding fMRI signals with 30-s forepaw stimulation (evoked-only vs. concurrent: epoch 2, 5 vs. 1, 3, 4). (E) The mean astrocytic Ca²⁺ traces of the two events (Left) and the simultaneously acquired fMRI time course (Right; gray line, difference; evoked-only, trial # = 84 vs. concurrent, trial # = 23, mean ± SEM, rats, n = 5). (F) The representative time-lapsed BOLD-fMRI map shows FP-S1 activation during the 30-s stimulation of evoked-only and concurrent events.