Organization of oscillatory motor pattern generation networks in the mammalian central nervous system

Several classes of models for oscillatory pattern generation networks are considered, and an experimental approach is described that has allowed the global organization to be elaborated for the system underlying respiratory movements. The experimental data suggest that in its most rudimentary configuration, this system is organized so that rhythmogenesis and pattern formation are separate functions involving distinct sets of neural mechanisms. This structure contrasts with network configurations that have been proposed for most vertebrate motor pattern generation networks where timing and spatiotemporal pattern are generated together by a common network. Data suggesting that there can be transformations of mechanisms of rhythmogenesis between different functional states have also been obtained. State-dependent transformational reorganization may be an important property of pattern generation systems, and at least for the respiratory system, the most general models for the global organization would include both kernel and transformational properties