Single-cell type analysis of wing premotor circuits in the ventral nerve cord of Drosophila melanogaster
authors: Erica Ehrhardt, Samuel C Whitehead, Shigehiro Namiki, Ryo Minegishi, Igor Siwanowicz, Kai Feng, Hideo Otsuna, FlyLight Project Team, Geoffrey W Meissner, David Stern, Jim Truman, David Shepherd, Michael H Dickinson, Kei Ito, Barry J Dickson, Itai Cohen, Gwyneth M Card, Wyatt Korff
doi: 10.1101/2023.05.31.542897
CITATION
Ehrhardt, E., Whitehead, S. C., Namiki, S., Minegishi, R., Siwanowicz, I., Feng, K., Otsuna, H., FlyLight Project Team, Meissner, G. W., Stern, D., Truman, J., Shepherd, D., Dickinson, M. H., Ito, K., Dickson, B. J., Cohen, I., Card, G. M., & Korff, W. (2023). Single-cell type analysis of wing premotor circuits in the ventral nerve cord of Drosophila melanogaster. Neuroscience. https://doi.org/10.1101/2023.05.31.542897
ABSTRACT
To perform most behaviors, animals must send commands from higher-order processing centers in the brain to premotor circuits that reside in ganglia distinct from the brain, such as the mammalian spinal cord or insect ventral nerve cord. How these circuits are functionally organized to generate the great diversity of animal behavior remains unclear. An important first step in unraveling the organization of premotor circuits is to identify their constituent cell types and create tools to monitor and manipulate these with high specificity to assess their function. This is possible in the tractable ventral nerve cord of the fly. To generate such a toolkit, we used a combinatorial genetic technique (split-GAL4) to create 195 sparse driver lines targeting 196 individual cell types in the ventral nerve cord. These included wing and haltere motoneurons, modulatory neurons, and interneurons. Using a combination of behavioral, developmental, and anatomical analyses, we systematically characterized the cell types targeted in our collection. In addition, we identified correspondences between the cells in this collection and a recent connectomic data set of the ventral nerve cord. Taken together, the resources and results presented here form a powerful toolkit for future investigations of neural circuits and connectivity of premotor circuits while linking them to behavioral outputs.
fleeting notes
papers to look up : Boettiger, 1960, Pringle, 1949
there are ventral unpaired median neurons (VUMs)
- efferent nuerons
- soma cluster at midline and are bilaterally summetric
- neuromodulatory cells - can be dopaminergic and octopaminergic
created a library of split gal4 lines
identified driver lines for power muscle types
- some are solely selective for DLMs
- some are selective for DVMs
- some have mixed expression in both
- identified neuron identity by staining muscle and neurons together.
could not separate DLMn c-f using genetics.
each DLM innervates a single muscle fiber. DLMna-b innervates 2 DLM fibers
DLMns have extensive ipsi and contralateral arborizations and receive inputs
DVMns are more morphologically distinct
DVM1 muscle is inenrvated by 3 MNs
DVM2 muscle is innervated by 2 MNs
DVM3 muscle i innverated by 2 MNs
DVMns have much less contralateral arborizations
control MNs can be classified into unilateral neurons or bilateral neurons that arborize in wing neuropil and neurons that arborize in wing and other neuropils
activation of DLMs had a relatively minor effect on wingstroke
- activation of DVMs had large behavioral effect - decreased stroke amplitude, and increased forward deviation and WBF
highlights
“To perform most behaviors, animals must send commands from higher-order processing 28 centers in the brain to premotor circuits that reside in ganglia distinct from the brain, such as 29 the mammalian spinal cord or insect ventral nerve cord. How these circuits are functionally 30 organized to generate the great diversity of animal behavior remains unclear”Page 2
“The VNC 48 receives and processes sensory information and is involved in generating most of the 49 locomotor actions that underlie fly behaviors such as walking (Bidaye et al., 2014, Tuthill and 50 Wilson, 2016, Chen et al., 2018, Howard et al., 2019), grooming (Seeds et al., 2014), escape 51 (King and Wyman, 1980, Trimarchi and Schneiderman, 1995, Card and Dickinson, 2008, von 52 Reyn et al., 2014), flight (Dickinson and Muijres, 2016, Schnell et al., 2017, O’Sullivan et al., 53 2018, Namiki et al., 2022), courtship (Clyne and Miesenbock, 2008, von Philipsborn et al., 54 2011, Shirangi et al., 2013, Shiozaki et al., 2024, Lillvis et al., 2024), and copulation 55 (Crickmore and Vosshall, 2013, Pavlou et al., 2016)”Page 2
“Premotor circuits in the VNC receive sensory input from peripheral organs in 62 the wings, legs, halteres, and abdomen (Tsubouchi et al., 2017) and descending commands 63 from the brain”Page 3
“For flying insects, such as the fruit fly, Drosophila melanogaster, wing behaviors comprise 75 some of the most fascinating examples of motor control.”Page 3
“To execute these wing behaviors, flies make use of a highly specialized wing motor system, 91 whose constituent muscles can be broadly separated into two distinct categories: the large, 92 asynchronous power muscles and the small, synchronous control muscles.”Page 3