Task-related setting of reflexes in invertebrates

Summary form only given. Task-relate setting of reflexes is described for the femur-tibia joint of stick insects. This joint is well-suited for the study of joint control because of its anatomy, the small number of neurons involved, and the well-defined behavioral states of the animal. The femur-tibia control system of the inactive animal has a high gain. The gain increases when the animal is disturbed. The high gain is necessary for the performance of catalepsy, the most important protection mechanism of the animal. In the active animal the femur-tibia control system is switched off and replaced by the active reaction. In the active animal there exist interjoint reflexes which are able to synchronize the movements of different joints during walking and searching. This kind of reflex is only present in the active animal. Active reaction and interjoint reflexes are modules of the walking-pattern generator. Switching on active reaction and interjoint reflexes is part of the formation of the pattern generator for walking and searching movements when the animal becomes active