13 FIG. 2: Coloured online. (a) A small-world network with 150 random long-range links (note, the tissue has about 2 × 10 4 nearest-neighbor links). (b) Spiral waves realized from a set of initial condition. (c) (d) Di ff erent asymptotic target wave patterns from two di ff erent initial conditions. The red nodes ( A$_{1}$ , B$_{1}$ ) and ( A$_{2}$ , B$_{2}$ , C$_{2}$ ) denote the centers of the target waves located in the source loops of Fig. 3, called source centers, and the blue nodes S TC$_{i}$ ( i = 1 , 2 , · · · , ) denote the sub-target centers driven by the source targets. All the green nodes denote the nodes connected with the various target centers with long-range interactions. The source loops found in Fig. 3 are denoted here A$_{1}$ bold line − − − → A ′ 1 L − RC − → B$_{1}$ bold line − − − → B ′ 1 L − RC − → A$_{1}$ in (c); and A$_{2}$ bold line − − − → A ′ 2 L − RC − → B$_{2}$ bold line − − − → B ′ 2 L − RC − → C$_{2}$ bold line − − − → C ′ 2 L − RC − → A$_{2}$ in (d).