Elife, https://doi.org/10.7554/eLife.34275 (2018).

In vertebrates and invertebrates, environmental information is processed in the brain and behavioral signals passed through descending neurons to regulatory centers that are proximal to effectors i.e. muscles. For Drosophila, only ~1100 neurons relay information to the ventral nerve cord that evokes the broad array of responses observed. To date, there is no high throughput way to relate specific descending neurons with a given behavior in flies. A new study remedies this with a technique to map the function of individual descending neurons. Using optogenetics, authors activated individual descending neurons and then employed an automated behavior classification system to analyze video captured data and assign a regulated behavior. Investigators classified between a third and a half of all descending neurons. The data revealed redundancy with many of the neurons eliciting similar behaviors that were stereotypical.