A, examples of waves at postnatal day (P) 5, P9 and P12. Each plot shows a raster of detected bursts, with waves colour-coded as in Fig. , and two-dimensional projections of selected waves, as indicated by arrows. B–E, median wave centre of activity trajectory (CAT) length (B), area (C), propagation speed (D) and activity density (E) for all waves at all developmental stages [postnatal day (P) 2: one retina, 106 waves; P3: two retinas, 191 waves; P4: four retinas, 204 waves; P5: four retinas, 188 waves; P6: five retinas, 99 waves; P7: three retinas, 72 waves; P8: four retinas, 232 waves; P9: eight retinas, 659 waves; P10: seven retinas, 631 waves; P11: six retinas, 945 waves; P12: four retinas, 718 waves]. Error bars indicate interquartile ranges. F, rasters of burst activity recorded at P13 and P15. No propagating activity can be seen at these ages.