Computer aided analysis of a locomotor leg reflex in the cockroach Periplaneta americana

1. Reflex responses were elicited in coxal muscles of cockroaches by imposing sinusoidal movement on the tibia of a leg. The muscle responses were analyzed with the aid of a computer program which is described in detail. 2. Responses of extensor muscles in the coxa to movement of the tibia of the same leg as that from which the responses were being recorded (intra-leg reflexes) most often occurred during extension of the tibia (Fig. 3). The phase of the response on the cycle of tibial movement increased as the frequency of imposed movement increased (Fig. 6). 3. Responses were detectable in coxal muscles to movement of the tibia of legs other than the one from which the responses were being recorded (inter-leg reflexes), but were very weak and labile. The phase of the response was extremely variable. 4. It is suggested that the intra-leg reflexes act to augment the thrust of a leg during walking. The possible role of the inter-leg reflexes during locomotion is also discussed.