Summa technologiae was the title the Polish science fiction writer Stanislaw Lem gave to a hefty tome of ruminations he published in 1964. In contrast to the similarly titled synthesis of theological knowledge compiled by Thomas Aquinas seven centuries earlier, Lem's book attempted not only to summarize the status quo of technology but also to divine its future. His Summa contains, in addition to several off−the−mark predictions, others that do anticipate present−day technologies. Some even appear in the pages of this issue. For example, Lem imagined an approach he called ‘phantomatics': the generation of ‘realities which for the intelligent life forms that inhabit them are indistinguishable from normal reality, yet are governed by different laws.' Virtual reality environments are now a commonplace, and in the laboratory they have enabled neuroscientists (Dombeck and Reiser) to take control of the feedback rules by which an animal's actions change what the animal experiences. Techniques exist for recording neuronal activity from animals in these (and other) environments, using single or multiple electrodes (Einevoll et al.) or genetically encoded optical reporter proteins (Looger and Griesbeck). Light−based microsurgery promises recordings with less damage to the brain surface (Kleinfeld et al.), while the development of miniaturized intracellular (Long and Lee) and optical (Kerr and Nimmerjahn) headstages is turning tethered preparations once again into freely moving animals