Central Pattern Generators: Mechanisms of Operation and Their Role in Controlling Automatic Movements

Abstract

Central pattern generators consist of sets of interconnected neurons able to generate a basic motor output pattern underlying automatic movements (respiration, locomotion, chewing, swallowing, etc.) without any afferent signals from the executive motor apparatus. They are divided into constitutive pattern generators, which are active throughout life (the respiratory generator), and conditional pattern generators, which control episodic movements (locomotion, chewing, swallowing, etc.). As the motor output of a pattern generator is defi ned by its internal organization, the activity of conditional pattern generators is initiated by a simple command arriving from the higher centers. The structural-functional organization of the locomotor pattern generators in the marine mollusk Clione, the lamprey, the frog embryo, and laboratory mammals (cats, mice, and rats) are described, along with pattern generators controlling respiratory and swallowing movements in mammals and pattern generators for discharges of the electric organs of gymnotiform fi sh. Generation of the rhythmic motor output is shown in all cases to be based on the endogenous (pacemaker) activity of specifi c groups of interneurons and interneural interactions. These two interacting mechanisms supplement each other, ensuring the reliable operation of pattern generators. The question of whether experience gained from studies of central pattern generators can be used for understanding the mechanisms of more complex brain functions, including cognitive functions, is discussed.

When the goal is to generate a series of activities: A self-organized simulated robot arm

“…In Fig. 5 we present for completeness the effect of changing the parameters E t , µ and τ f of the ED dissipation function dynamics, see (6). We find the generating principle to be robust, viz that the dependency of P close and P new on E t , µ and τ f is moderate.…”

“…It is well known that gaits and other regular muscle contractions, like breathing [6], are induced in many cases by central pattern generators [7,8], even though it is currently controversial whether this is the case for biped locomotion [9], viz for human walking. Abstracting from animal models, one may ask conversely to which extent compliant locomotion may be generated via self-organizing principles [10], that is in the absence of top-down control in the form of a central pattern generator.…”

Expanding our horizons: central pattern generation in the context of complex activity sequences

“…Such approaches might narrow down the CNS region(s) generating the sequence, to be explored further using additional approaches. Such a CPG mindset may also draw attention to the extensive research on intrinsic and synaptic ion channel mechanisms that establish timing in traditional CPGs (Arshavsky et al, 2016;Harris-Warrick, 2010;Marder and Calabrese, 1996;Marder et al, 2014;Selverston, 2010) and the computational modeling of such CPGs that has revealed mechanisms likely to generate transitions between sequence elements (Ausborn et al, 2018;Grillner, 2006;Hao et al, 2011;Hull et al, 2016;Marder et al, 2014;Selverston, 2010;Shevtsova and Rybak, 2016). The roles of such mechanisms can then be explored for complex movement and nonmotor activity sequences, which may increase our understanding of their neural control.…”

“…Thus, the field of central pattern generation was born. In the years following, central pattern generators (CPGs; see Glossary) were demonstrated for a wide array of natural movements, including multiple forms of locomotion, breathing, scratching, calling, chewing, stridulating, digesting and copulating (Arshavsky et al, 2016;Delcomyn, 1980;Marder and Calabrese, 1996), although it was also recognized that sensory feedback modifies these basic movement patterns as needed, especially under rapidly changing environmental conditions. CPGs were found in vertebrates and invertebrates, for both episodic behaviors (like locomotion) and continuous behaviors (like breathing).…”

“…CPGs were found in vertebrates and invertebrates, for both episodic behaviors (like locomotion) and continuous behaviors (like breathing). The physiological mechanisms underlying CPGs were studied at multiple levels of analysis, especially for small invertebrates (Arshavsky et al, 2016;Harris-Warrick, 2010;Marder and Calabrese, 1996;Marder et al, 2014;Selverston, 2010), and further elucidated by computational modeling (Grillner, 2006;Hull et al, 2016;Marder et al, 2014;Selverston, 2010). Brown, von Holst and Wilson developed the idea of central pattern generation in their studies of rhythmic locomotion but did not restrict its application to rhythmic movements.…”