Longitudinal diffusion along a 10 μm length of dendrite. Plots show calcium transients in the 0.1 μm thick submembrane shell at different positions along the dendrite. Solid black line: 0.5 μm; dashed: 1.5 μm; dot-dashed: 4.5 μm. (a) Diameter is 1 μm. (b) Diameter is 4 μm. Calcium influx occurs in the first 1 μm length of dendrite only. Each of ten 1 μm long compartment contains four radial shells. Blue dotted line: calcium transient with only radial (and not longitudinal) diffusion in the first 1 μm long compartment. All other model parameters as in Figure 6.5.