Fig 8. The minimal value of MD as a function the control parameter f for the combined “spine economy max and wire min” principle.

Blue squares correspond to Gamma (n = 2) distribution of spine sizes and red diamonds to Log-normal distribution. The notion of spine economy max is mixed with different types of wire cost min principle: wire length in (A), wire surface area in (B), wire volume in (C), and conduction delays in (D). In almost all panels MD has extremely shallow minima for f ∼ 0.1–0.3, and then MD increases either weakly or abruptly as f increases further (for f = 1 MD is the same for both distributions of spine sizes). The exception is the mixture of wire volume min and spine max (panel C), where MD is practically constant. For all panels θ = 0.321 μm³.