Fig. 5: Synapses in NCLX-KO slices exhibit higher frequency-facilitation and more frequent spontaneous activity.

a Representative fEPSPs recorded from the CA1 area when delivering 5 stimuli to the Schaffer collaterals at 20 Hz in acute slices prepared from WT (black) and NCLX-KO (blue) mice (stimulation artifact was blanked). b Frequency-facilitation is higher in NCLX-KO slices. fEPSP amplitudes normalized by first response in each train (mean ± SEM), in WT and NCLX-KO slices stimulated at 20 Hz (n = 22 and 22 recordings from 8 WT and 9 NCLX-KO mice, respectively). The stimulation intensity in each train was set to produce an initial response of ~0.3 mV (see d). p < 0.001, two-way repeated-measures ANOVA (F = 2452, DF = 1,21) with Tukey’s post-hoc analysis: p = 0.029, 0.002, 0.003, 0.0006 (t = 3.15, 4.48, 4.31, 5.11; DF = 63), respectively. c PPR is higher in NCLX-KO slices. Quantification of the P2/P1 ratio obtained at various stimulation frequencies. Stronger facilitation was observed in NCLX-KO slices at all frequencies. 5 Hz: **p = 0.002 two-sided Student’s t test (n = 23,25, t = −3.24, DF = 46), 10 Hz: *p = 0.015 (n = 21,18, t = −2.549, DF = 37); 20 Hz: **p = 0.003 (n = 22,22, t = −3.14, DF = 42); 50 Hz: ***p = 0.0005 (n = 19,18, t = −3.82, DF = 35). d Response/input plot. The fEPSP response amplitude (±sem) is plotted as a function of the stimulation intensity (n = 7 WT, n = 11 NCLX KO). The stimulation intensity is normalized by the intensity in (mA) producing a response of ~0.3 mV in each slice. The graph illustrates that the responses are not saturated in both WT and NCLX-KO slices. e Intracellular recording of spontaneous mEPSCs. Representative traces recorded from WT (black) and NCLX-KO (blue) slices under resting conditions, in the presence of TTX. f Interevent intervals in NCLX-KO slices are longer. Interevent intervals were averaged in n = 5 and 6 slice recordings from 3 WT and NCLX-KO mice (0.65 ± 0.11, 1.14 ± 0.10 mean ± SEM sec), **p = 0.0079, two-sided Student’s t test (t = −3.397, DF = 9). g mEPSC amplitudes are smaller in NCLX-KO slices. Cumulative plot of the mEPSC amplitudes recorded in WT and in NCLX-KO slices (n = 990 and 978 events, respectively). ***p < 0.001, Kolmogorov–Smirnov test (D = 0.163, Z = 3.61).