Activity-driven collapse (A and B) of two types of projections (EphA3+ and EphA3-) is different from noise-driven collapse (C and D) ( E
= 0). (A and C) The axonal positions in the target are shown as a function of the position of their origin in retina. Individual EphA3+/EphA3- axons are represented by blue/cyan points. (B and D) The distribution of terminal positions in the target for subset of axons originating from different retinal locations marked 1-3 in A and C. (B) includes projections for a single instance of mapping. (D) includes sum of projections for 1500 maps, which is necessary due to the degree of noise in the absence of correlated activity.