(a) The schematic illustration of SRDP. 10 consecutive pulses were applied then read the EPSC. The pulse amplitude and reading voltage were fixed at 2 V and 1 V, respectively. The pulse widths were 100 ms. (b) EPSC changes as a function of frequency. (c) Experimental setup of STDP, a positive and negative pulse pair was applied on the pre-synaptic side. The positive pulse equals to pre-synaptic spike and negative pulse equals to post-synaptic spike. (d) Change of the synaptic weight as a function of the relative timing between the pre- and post-synaptic pulses, Δ t = t post − t pre .