TY - JOUR T1 - A command-like descending neuron that coordinately activates backward and inhibits forward locomotion JF - bioRxiv DO - 10.1101/339556 SP - 339556 AU - Arnaldo Carreira-Rosario AU - Aref Arzan Zarin AU - Matthew Q. Clark AU - Laurina Manning AU - Richard Fetter AU - Albert Cardona AU - Chris Q. Doe Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/06/05/339556.abstract N2 - Command-like descending neurons can induce many behaviors, such as backward locomotion, escape, feeding, courtship, egg-laying, or grooming. In most animals it remains unknown how neural circuits switch between these antagonistic behaviors: via top-down activation/inhibition of antagonistic circuits or via reciprocal inhibition between antagonistic circuits. Here we use genetic screens, intersectional genetics, circuit reconstruction by electron microscopy, and functional optogenetics to identify a bilateral pair of larval “mooncrawler descending neurons” (MDNs) with command-like ability to coordinately induce backward locomotion and block forward locomotion; the former by activating a backward-specific premotor neuron, and the latter by disynaptic inhibition of a forward-specific premotor neuron. In contrast, direct reciprocal inhibition between forward and backward circuits was not observed. Thus, MDNs coordinate a transition between antagonistic larval locomotor behaviors. Interestingly, larval MDNs persist into adulthood, where they can trigger backward walking. Thus, MDNs induce backward locomotion in both limbless and limbed animals.HighlightsMDN command-like descending neuron induces backward larval locomotionMDN neurons coordinately regulate antagonistic behaviors (forward/backward locomotion)MDN-motor circuit validated at structural (TEM) and functional (optogenetic) levelsMDN neurons induce backward locomotion in both limbless larva and limbed adult ER -