In footnote 21 of a groundbreaking paper on astrocyte communication published in Science in 1990, there is a prediction. The authors, Cornell-Bell et al., showed calcium waves propagating widely through monocultures of astrocytes in response to glutamate application. But in the footnote, they cautioned that their observations could be considered in some respects an experimental artifact. The authors believed that instead of the promiscuous propagation of calcium waves spreading throughout the entire population of astrocytes in culture, that in the brain, the communication would be far more discrete and more interesting.