Figure 3.

Simulation of a single burst in a 30 × 30 array. Contour maps of activation times for the cellular automaton model during a rotor burst. (A) Unidirectional block. The wave is initiated from the random firing of more than two neighboring sites. Heterogeneity results in unidirectional propagation upward. (B and C) Formation of two mirror-image rotors. The excitation doubles back and invades the site of block to form a rotor. (D and E) Rotation of the mirror-image pair of rotors. The rightmost rotor dominates and the leftmost rotor dies out first. (F) Termination of the remaining rotor.