Regulation of coordinated muscular relaxation by a pattern-generating intersegmental circuit

Abstract

Typical patterned movements in animals are achieved through combinations of contraction and delayed relaxation of groups of muscles. However, how intersegmentally coordinated patterns of muscular relaxation are regulated by the neural circuits remain poorly understood. Here, we identify Canon, a class of higher-order premotor interneurons, that regulates muscular relaxation during backward locomotion of Drosophila larvae. Canon neurons are cholinergic interneurons present in each abdominal neuromere and show wave-like activity during fictive backward locomotion. Optogenetic activation of Canon neurons induces relaxation of body wall muscles, whereas inhibition of these neurons disrupts timely muscle relaxation. Canon neurons provide excitatory outputs to inhibitory premotor interneurons. Canon neurons also connect with each other to form an intersegmental circuit and regulate their own wave-like activities. Thus, our results demonstrate how coordinated muscle relaxation can be realized by an intersegmental circuit that regulates its own patterned activity and sequentially terminates motor activities along the anterior-posterior axis.

Extraction of bouton-like structures from neuropil calcium imaging data

“…C.4.B). It has been shown that several interneurons are activated in either forward or backward waves (Carreira-Rosario et al, 2018; Fushiki et al, 2016; Hiramoto et al, 2021; Kohsaka et al, 2019). In our data of pan-neuronal calcium recordings in the neuropil, such direction-specific activity could be observed only in the fine component (Fig.…”

“…The copyright holder for this preprint this version posted May 29, 2021. ; https://doi.org/10.1101/2021.05.28.445372 doi: bioRxiv preprint al., 2016; Hiramoto et al, 2021;Kohsaka et al, 2019). Accordingly, the decomposition step is critical to extract the proper activity of the neurons.…”