Recordings were parsed according to the efficiency of granule cell synaptic excitation during TBS, which was expressed as mean burst depolarization (m.b.d.) and spike frequency (s.f.). “Weak TBS” corresponds to data in Figure 2, A₁ andB₁, “strong TBS” corresponds to data in Figure 2, A₂ and B₂, and average LTP time courses are summarized in Fig. 2C. EPSP potentiation was higher after strong than weak TBS. It should be noted that the initial EPSP size was comparatively smaller when weak rather than strong TBS was observed. Data in the two groups were significantly different (p < 0.01).