Trophic neuron-glia interactions and cell number adjustments in the fruit fly
Alicia Hidalgo, Kentaro Kato, Ben Sutcliffe, Graham McIlroy, Simon Bishop, Samaher Alahmed.
Glia, epub 1 Dec 2010, doi: 10.1002/glia.21092
If you'd like to know a bit more, I recommend starting from the very beginning, with the 1986 Nobel lecture of Rita Levi-Montalcini, describing the discovery of nerve growth factor (NGF). It makes for an interesting story of how science used to be done.
Image from the work of Levi-Montalcini, not us