Imaging of Ca2+ responses to whole cell extrasynaptic NMDA receptor activation. Ca2+ responses were measured in cells loaded with X-Rhod 1-AM using the same protocol shown in Figure 2A except 10 μM nifedipine (nif) was included in the TTX containing solution. (A) Representative recording from a coverslip following overnight vehicle treatment. (B) Representative recording from a coverslip following overnight AP bursting. Grey traces show the results recorded simultaneously from the soma (including nucleus) of multiple cells in the same field of view and black traces show the average of these cells. (C) Cumulative data are shown from vehicle treated non bursting coverslips (Con, n = 261 cells on 5 coverslips), vehicle treated coverslips showing spontaneous bursting events (Spon Burst, n = 225 cells on 4 coverslips) and bicuculline-treated coverslips, all of which showed synchronous rhythmic AP bursting (Bic, n = 258 cells on 5 coverslips). The peak of the NMDA response is normalized to the response to ionomycin (Fmax) in the same cell. Bars represent the mean and whiskers the SEM. The vehicle treated group was significantly different from the other two groups (* p < 0.0001, ANOVA, Tukey's posthoc tests).