Figure 4
Presynaptic Ca2+enhances an efficiency of probability-driven facilitation. A) shows a linear correlation between the probability of releasing glutamate and the amplitude of unitary synaptic responses (uEPSCs). B) shows the comparisons of linear correlations between release probability and uEPSCs induced by eight spikes at 10 Hz (red symbols) and 20 Hz (blues, n = 6). The efficiency of probability-driven facilitation is high when presynaptic spikes are 20 Hz. C) shows the comparisons of linear correlations between release probability and uEPSCs induced by eight spikes under control (red-filled symbols) and adenophostin-A infusion (blues, n = 9). The efficiency of probability-driven facilitation is high when presynaptic Ca2+ is elevated by AD infusion. D) A plot shows the ratios of changes in uEPSCs to release probability vs. the levels of release probability, i.e., the higher release probability is, the higher efficiency of probability-driven facilitation. Lines in A ~ C illustrate linear dynamical fitting.