Figure 4.

[Ca²⁺]_pre determines not only the amplitude of average eIPSCs but also the range of eIPSC fluctuations. (A) The mean eIPSC amplitude increased with about the third power of [Ca²⁺]_pre (line). eIPSCs were averaged within ΔF/F₀ bins. The [Ca²⁺]_pre bin width was set to 0.05. (B) Individual data points corresponding to the experiment shown in A. The gray bar delineates one bin of [Ca²⁺]_pre. Fourteen individual data points were available for this level of [Ca²⁺]_pre (0.6–0.65), giving an eIPSC average and SD of 52.2 pA and 24.5 pA, respectively. All data are from the same bouton. Pulse duration: 1 ms. (C) eIPSCs fluctuate despite a similarity of [Ca²⁺]_pre. Traces are presented in the order of acquisition. Data in A and B and in C were from different boutons.