Lloyd A L, Lloyd D
Department of Zoology, University of Oxford, UK.
Biosystems. 1993;29(2-3):77-85. doi: 10.1016/0303-2647(93)90085-q.
Controlled chaos may be important for the generation of rhythmic behaviour in living systems. A model is proposed in which the central circadian oscillator is a chaotic attractor. Whereas a limit cycle mechanism (previously invoked to explain circadian clocks as well as ultradian clocks and cell division cycles) can provide only a single stable periodic orbit, a chaotic attractor can generate rich dynamic behaviour. Control by feedback makes accessible a selected stabilized orbit; this can be chosen so as to optimize system performance. Such a system can accommodate a wide variety of requirements, e.g. that a single clock mutation can affect both period and temperature compensation, and the generation of higher periods from an ultradian oscillator. Simultaneous operation of more than one clock (with differing periods) may require a high-dimension chaotic attractor. Attractive features of such a model include versatility of period selection (e.g. as in the per mutants of Drosophila) and the use of control elements of the type already well known in metabolic circuitry.
受控混沌对于生物系统中节律行为的产生可能很重要。本文提出了一个模型，其中中央昼夜节律振荡器是一个混沌吸引子。虽然极限环机制（以前被用来解释昼夜节律时钟以及超日节律时钟和细胞分裂周期）只能提供一个单一的稳定周期轨道，但混沌吸引子可以产生丰富的动态行为。通过反馈进行控制可以实现选定的稳定轨道；可以选择该轨道以优化系统性能。这样的系统可以适应各种各样的要求，例如单个时钟突变可以同时影响周期和温度补偿，以及从超日节律振荡器产生更高的周期。同时运行多个（具有不同周期的）时钟可能需要一个高维混沌吸引子。这种模型的吸引人的特点包括周期选择的多样性（例如在果蝇的per突变体中）以及使用代谢回路中已经熟知的那种控制元件。
