But the research that McCarthy is about to discuss could put a stop to the enthusiasm.“I’m presenting work from genetic studies that fly in the face of gliotransmission,” he begins. Most studies so far have investigated astrocytes cultured in dishes, and bombarded them with calcium to elicit an effect. It has long been suggested, however, that these methods aren’t specific enough to astrocytes, and might be affecting neurons as well. What is needed is a way to target astrocytes alone. So McCarthy has developed genetically engineered mice in which astrocytes can't signal normally. The mutations seem to have no effect on neuronal transmission in the brain.

His group’s finding could come as a relief to some. Given the enormous neural complexity that gliotransmission would imply,“people don’t want astrocytes to be involved”, says Phil Haydon, a neuroscientist who studies glia at Tufts University in Boston, Massachusetts. But many, including most at the Amsterdam meeting, have built their careers on gliotransmission. In addition to their effects on the day-to-day functioning of the central nervous system, glia have opened new avenues of research into sleep, as well as psychiatric and neurological disease. Now, researchers are being forced to prove McCarthy wrong, or re-evaluate the fundamental precepts upon which the field was built. David Attwell, a neuroscientist at University College London, says that emotions in the community are running high.“If someone comes along and says that everything you’ve done is wrong, it’s like you’ve wasted your life,” he says.“It’s become quite a polarized field, just in the last year or two.”