eLife assessment
The aim of this important study is to functionally characterize neuronal circuits underlying the escape behavior in Drosophila larvae. Upon detection of a noxious stimulus, larvae follow a series of stereotyped movements that include bending of their body, rolling and crawling away. This paper combines quantitative behavioral analyses, cell-type specific manipulations, optogenetics, calcium imaging, immunostaining, and connectomic analysis to provide convincing evidence of an inhibitory descending pathway that controls the switch from rolling to fast crawling behaviors of the larval escape response.