Abstract: In 2026, Eon Systems released a non-peer-reviewed demonstration of a digital fruit fly (Drosophila melanogaster),
combining the FlyWire connectome model with a virtual body simulation, which sparked discussions on the boundaries of wholebrain emulation. By using the connectome as a structural constraint on neural activity and coupling it with a virtual body, the system demonstrated behavior control such as grooming and foraging. While such demonstrations remain in the early stages of exploration,they suggest  that digital brain research is gradually shifting from static connectome maps towards dynamic, operational, interactive, and verifiable neural simulation systems. With the rapid development of neuroscience, brain-inspired intelligence, and computing technologies, digital brain research has become a new frontier in global technological competition. This paper traces the evolution of digital brain simulation techniques from Caenorhabditis elegans to D. melanogaster, exploring the technical routes, scientific
significance, global landscape, and limitations of digital brain research. By reviewing the pioneering attempts at whole-brain emulation of C. elegans and the leap from structure to function in D. melanogaster whole-brain simulation, we reveal the critical role of digital brain technology in the mechanisms of intelligence emergence. This review is expected to provide useful insights for future research on digital brain systems.