Fig 6. Balanced plasticity of the mean synaptic weight.

(A) When the STDP rule is balanced and potentiation-dominated, the unstable fixed point for p is negative and decreases with the connection probability. (B) When the STDP rule is balanced and depression-dominated, the unstable fixed point is positive and increases with the connection probability. (A,B) Left: Dashed lines mark bounds for the mean synaptic weight, at 0 and p ₀ W ^max. Black curves track the location of the unstable fixed point of p as the connection probability, p ₀, varies. Black dots mark initial conditions for the right panels. (A,B) Right: Dynamics of the mean synaptic weight in each of the regimes of the left plots. Red lines mark the reduced theory’s prediction (Eq (9)) and shaded lines the result of simulating the full spiking network (10 trials are plotted individually; they lie within line thickness of each other). Note that the ordinate axis has different limits in the left and right sides of the figure.