Figure 6.

CFs in Z⁺ zones contain a larger pool of release-competent vesicles. A, Top, Overlay of 10 consecutive EPSCs from representative Z⁺ (gray traces) and Z⁻ (black traces) Purkinje cells collected at 0.033 Hz in 4 mm extracellular Ca²⁺ in the presence of 10 mm γ-DGG (to relieve AMPA receptors from saturation). Recordings were made at a holding potential of −40 mV. Bottom, Same traces presented at an enlarged scale. B, Graph of variance versus mean EPSC amplitude calculated from at least 20 consecutive CF EPSCs. CF responses in Z⁺ zones (red symbols) exhibited larger amplitudes (p = 0.02) and higher variance (p < 0.02) than CF responses in Z⁻ zones (blue symbols), indicating that CFs in Z⁺ zones contain a larger pool of release-competent vesicles. Squares and error bars represent mean ± SEM.