Figure 3.

Illustration of the present memristive neural plasticity model in comparison to synaptic plasticity data from neurophysiologic experiments: (a) Schematic of the given model: LTP occurs whenever one of the neurons (A or B) is spiking (whichever reaches the threshold voltage ϴ_thres) and the membrane potential u(t) of the opposite neuron is positive (above the black solid line in a). LTD is introduced if at the spike time the opposite neuron has a negative u(t). Thus, the role of pre and post neuron can change so that a bi-directional coupling between the neurons can be obtained. (b) Pre-synaptic stimulation under voltage clamp condition with 25 spike repetitions. Experimental data are taken from ref.²⁸ shown as dots. (c) Spike-timing-dependent plasticity is compared to experimental data from ref.². (d) Frequency dependency of spike pairs for pre-post (blue lines) and post-pre (red lines) pairing. While in the upper graph the synaptic weight is held constant between spike events, a weight dependent depression was applied to obtain the data shown in the lower graph. Solid lines are model data, while dots are experimental data taken from ref.⁴. The used simulation parameters are listed in Table 1. The parameters have been adjusted in such a way that the same set of parameters can be used for all illustrated plasticity emulations.