Self-organized hierarchical structure in a plastic network of chaotic units

Formation of a layered structure is studied in a globally coupled map of chaotic units with a plastic coupling strength that changes depending on the states of units globally and an external input. In the parameter region characterized by weakly chaotic and desynchronized dynamics, units spontaneously form a hierarchical structure due to the influence of the input. This hierarchical structure is not fixed in time, and is successively reorganized. It is found that the distribution of lifetimes of the structure obeys a power law. The possible relevance of the present result to information processing in the brain is briefly discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.