Metachronal propagation of motor activity.

A diverse array of biomechanical systems has evolved to satisfy locomotor requirements (reptation, swimming, walking, etc.) and in all cases, successful behabior achievement requires the integrated functioning of various segments, to ensure the appropriate positioning of the different body regions. From comparative studies on a variety of invertebrate and vertebrate organisms, it is now established that the basic motor patterns underlying limb and/or trunk movements during locomotion are driven by central networks of neurons, so-called central pattern generators (CPGs). In limbless animals such as leech, lamprey, snakes... body propulsion is driven by alternate left- right trunk muscle contractions that occur sequentially (or metachronally) along the body length. Here, we highlight some common principles of motor control involving metachronal activity that are shared by multisegmental systems. In a first step we will review systems in which the neural mechanismsthe that underlie modular linear distribution have been extensively studied. Finally, we will review modeling studies that have been performed to better understand the fundamental mechanisms that underlie metachronal propagation.