Stability and Competition in Multi-spike Models of Spike-Timing Dependent Plasticity
Fig 8
Stability and competition in the NMDAR-based model.
A. Fixed points of ⟨w⟩ as functions of the ratio between the maximum potentiation and depression parameters. When A+/A− is smaller than 0.042, two nontrivial fixed points exist. At higher values, they collide and disappear. B. The w-dependent drift at the stable fixed point, as a function of A+/A−, which changes sign at A+/A− = 0.025. In the dark gray region, a stable fixed point exists and the w-dependent drift is negative. In the light gray region a stable fixed point exists and the w-dependent drift is positive, and in the white region there is no stable fixed point. C-E. The average drift when A+/A− is 0.01, 0.03 and 0.05, respectively. Filled circles represent stable fixed points and the open circle an unstable fixed point. The gray shading is the result of simulations, and the solid curve is the analytical result. F-H. The steady-state distributions corresponding to the parameters in C-E. I-K. Synaptic competition between correlated and uncorrelated synapses corresponding to the parameters in C-E. Parameters are , and the time constants are as in Table 2.