Diameter optimization for optimal current transfer in simplified dendritic cable models. (A) Optimal diameters for maximal charge transfer in four unbranched cable models, each composed of six segments of equal length (200, 300, 400 and 500 μm from bottom to top) and all attached to a cylindrical axon (20 μm in diameter, 2 mm long). Scale x : 1 mm y : 10 μm. Red: diameter tapering. (B) Diameter optimization in branched structures with six 300 μm-long segments each, sorted by error size (marked values) as defined in Equation (4). Part of the axon at the bottom of each tree is cut for presentation. (C) Dendrite diameter tapering for all models shown in B, when the path from root to terminal is normalized.