Calcium diffusion rates control spatial gradients of calcium while buffer concentrations control transient decay dynamics. (a) Spatial dynamics at 2 ms and 10 ms for a spherical spine. We varied the diffusion coefficient and the mobile buffer concentration. Based on this phase diagram, the diffusion coefficient dictates the range of the spatial gradient of calcium, while buffer binding rate influences the lifetime of the spatial gradient. (b) Temporal calcium dynamics at the top of the spherical spine. The temporal dynamics show that the concentration of mobile buffer affects the lifetime of the calcium transient, as expected. (c) AUC shows that lower mobile buffer concentration and lower diffusion rates leads to higher levels of total calcium. (d) Peak concentration is primarily determined by the diffusion rate of calcium and is almost independent of mobile buffer concentration.