A quantitative model of walking incorporating central and peripheral influences

Using the experimental results of Cruse and Saxler (1980a, b) and other authors (Graham, 1972; Pearson, 1972; Bässler, 1977, 1979) a quantitative model is developed in order to describe the behaviour of the systems controlling the leg movements of a walking insect. The whole model consists of six subsystems each of which controls the movement of an individual leg. The single subsystem (Fig. 1) consists of a central part which can assume two modes (protraction, retraction) the transition between which can be controlled by sensory influence. The central part produces the reference input for a feedback loop which controls the leg position. The reference input is however also determined by influences from other subsystems. Four different types of such connections are assumed to exist between the subsystems. Two of these produce alternating (t1, t3), two others in phase coupling (t2, t4) between the subsystems to be connected. These connections can transfer information originating from the central part as well as from the periphery of other subsystems. The model is capable of describing either quantitatively or qualitatively the experimental results of Cruse and Saxler (1980a, b) (see Figs. 3 and 4). In addition it is capable of describing the results of other authors, e.g. the temporal leg coordination of the free walking animal (Graham, 1972).Supported by DFG (Cr 58/1)