Central pattern generating networks in insect locomotion

Abstract

Central pattern generators (CPGs) are neural circuits that based on their connectivity can generate rhythmic and patterned output in the absence of rhythmic external inputs. This property makes CPGs crucial elements in the generation of many kinds of rhythmic motor behaviors in insects, such as flying, walking, swimming, or crawling. Arguably representing the most diverse group of animals, insects utilize at least one of these types of locomotion during one stage of their ontogenesis. Insects have been extensively used to study the neural basis of rhythmic motor behaviors, and particularly the structure and operation of CPGs involved in locomotion. Here, we review insect locomotion with regard to flying, walking, and crawling, and we discuss the contribution of central pattern generation to these three forms of locomotion. In each case, we compare and contrast the topology and structure of the CPGs, and we point out how these factors are involved in the generation of the respective motor pattern. We focus on the importance of sensory information for establishing a functional motor output and we indicate behavior‐specific adaptations. Furthermore, we report on the mechanisms underlying coordination between different body parts. Last but not least, by reviewing the state‐of‐the‐art knowledge concerning the role of CPGs in insect locomotion, we endeavor to create a common ground, upon which future research in the field of motor control in insects can build.

Reproducing Five Motor Behaviors in a Salamander Robot With Virtual Muscles and a Distributed CPG Controller Regulated by Drive Signals and Proprioceptive Feedback

“…This also means that we would expect similar results with a model that includes head stabilization as observed in the animal during forward terrestrial stepping (Ryczko et al, 2015). Our results with inverted weights are reminiscent of the reversal of the effects of sense organs that signal forces on a leg when switching from forward to backward stepping in the stick insect (Akay et al, 2007, for review see Mantziaris et al, 2020). The mechanism underlying such a switch in sensory encoding could involve an interplay between the descending drive to the CPG and sensory feedback.…”

A spinal organ of proprioception for integrated motor action feedback

“…Proprioception is essential for animal behavior, and its importance in motor control has long been recognized (Akay et al, 2014;B€ assler and B€ uschges, 1998;B€ uschges et al, 2001Grillner, 1975Grillner, , 1985Grillner and El Manira, 2020;Lam and Pearson, 2002;Mantziaris et al, 2020;Pearson, 1995Pearson, , 2004Rossignol et al, 2006;Tuthill and Azim, 2018). However, the complex interplay between peripheral proprioceptive feedback and central motor command circuits remains poorly understood.…”

A plausible mechanism forDrosophilalarva intermittent behavior

“…Displacement runs are intrinsically discretized, comprised of repetitive, stereotypical peristaltic strides. These stem from segmental central pattern generator circuits (CPG) located in the ventral nerve chord, involving both excitatory and inhibitory premotor neurons and oscillating independently of sensory feedback (7). A 'visceral pistoning' mechanism involving head and tail-segment synchronous contraction underlies stride initiation (8).…”