Fig. 2

Extrasynaptic glutamate is cleared faster during high-frequency stimulations in the ACC in contrast to the BC. a Typical experiment showing the extent of expression of iGluSnFR in the adult mouse barrel cortex. The glutamate sensor was expressed specifically on the plasma membrane of cortical astrocytes (GFAP-iGluSnFr, green channel). In red, astrocytes were stained with Sulforhodamine-101 (SR-101). Theta-glass electrode for synaptic stimulation was placed in the inner layer one and glutamate was imaged from a region of interest (ROI) adjacent to the electrode. Scale bar = 40 μm. a–c Upon synaptic stimulation: single stimulation, 10 × 10 Hz (b), 10 × 50 Hz, and 10 × 100 Hz (c) robust and consistent increases in iGluSnFr emission could be detected. Thick lines represent the average of the responses and the mono-exponential fit of the decay. d The decay kinetics of the averaged transients are slower following 100 Hz stimulation compared with 50 Hz (n = 8, **P < 0.001) and decay kinetics of the transients at both 50 and 100 Hz are significantly slower than those from a single pulse (n = 8, N = 3, ***P < 0.0001). e–g same as (a–c) for the ACC. Scale bar = 40 μm. h The decay kinetics of the averaged transients are faster following 100 Hz stimulations compared with 50 Hz (n = 8, **P < 0.001) and decay kinetics of the transients at both 50 and 100 Hz are significantly slower than those at single pulse (n = 8, N = 3, ***P < 0.0001). n = number of slices, N = number of mice. Data are mean ± SEM. One-way ANOVA with Bonferroni post hoc test