Patterned Activity of Co-Ordinated Motor Units, Studied in Flying Locusts

Abstract

1. A brief survey of the locust flight system is presented as background for this and future studies. Included are descriptions of the wing movements, the aerodynamic parameters and the pertinent muscle anatomy and physiology. 2. A procedure has been designed which makes it possible to study a complex locomotory pattern in terms of the activities of single nervous and muscular units, in this case during normal flight of locusts. 3. We have found a detailed repetitive pattern which is precisely correlated with the wing movements. Fig. 24 shows the pattern during normal flight. Variations in the details of the pattern are also correlated with significant variation in the movements. 4. During average flight most of the flight motor units fire a single time per wing stroke. In low-powered flight numerous units are inactive. With increase in power additional units are recruited and active ones may fire twice or more during a specific phase of a single wingstroke. 5. Increase in wingstroke frequency is correlated with increase in number of active units and with earlier onset of activity so that the wing movements are braked at top and bottom by muscular activity as well as by other restoring forces. 6. Lift is controlled by changes in wing twisting which are mainly due to changes in activity of a single two-unit muscle for each wing, the subalar muscle.