Preparation and execution of movement: parallels between insect and mammalian motor systems.

1. The organization of the motor systems underlying locomotion in insects and mammals is surprisingly similar. There are also parallels between the insect motor system and the system underlying reaching and the occulomotor system in primates. 2. The movements generated by all these systems are planned or prepared before their execution and there is a partial separation of circuits for preparation and execution. 3. These circuits consist of multiple descending pathways interconnected to form overlapping loops which work co-operatively to determine the motor output. Thus, both insect and mammalian motor systems can be treated as parallel distributed (PDP) systems. 4. This enables a comparison of functional levels of processing in the different systems and also provides a basis for modelling motor systems with attractor neural networks.