Developmental changes in presynaptic ∫νΔF/F0. (A) Representative traces of ∫νΔF/F0 at two developmental ages (A1, P6; A2, Adult (P85); Mg Green) (B) Summary data of ∫νΔF/F0 vs. age. ANOVA with Fisher’s post hoc comparison of significance of ∫νΔF/F0 vs. age between groups: F40,7 = 6.65; P = 0.00001; P1–P3, n = 8; P6, n = 12; P9, n = 5; P12, n = 4; P15, n = 3; P21–P27, n = 9; P30, n = 3; adult, n = 4 animals. (C) Concurrent recordings of fEPSP PPF and ∫νΔF/F0 (P1–P6, grey open squares, n = 20 animals; P9–adult, black circles, n = 15 animals) fit by least-squares linear regression. *P < 0.05, **P < 0.01 and ***P < 0.001.