Huang, C. et al. Nat. Commun. 9, 872 (2018).

Chronic window preparations allow longitudinal imaging of neuronal activity in rodent brains, but long-term imaging has so far not been possible in the fruit fly brain. Huang et al. combine laser microsurgery with a transparent epoxy window in the fly head cuticle. Flies prepared in this manner had a similar life span as untreated animals and were not affected in their behavior. The researchers used this preparation to visualize neuronal morphology by two-photon microscopy. They also conducted calcium imaging to investigate responses to odor stimulation and to perform voltage imaging upon mechanical stress. The flies could be released after each session and repeatedly imaged over the course of their life.