Cooperation, not hierarchy Almost as soon as the single-neuron doctrine was formulated, an alternative viewpoint started to emerge, initially among a small number of researchers, including E. Roy John of NYU and W. R. Freeman of the University of California at San Diego. They argued that information in the brain is stored and processed only when millions of neurons work together with their electric potentials correlated or synchronized in patterns of firings at various frequencies. These cell assemblies, as they are called, are not anatomical entities but temporary functional collections of neurons, scattered across wide areas of the brain or even the entire brain, whose firings are synchronized at a given frequency. Importantly, each neuron can simultaneously be part of several assemblies, each operating at different frequencies. By analogy, this is like a person playing one drum in time with one group of drummers and another in time with a different, faster group of drummers, or playing cello in tune with one group and an oboe with another.
Cell assemblies make the problem of binding more tractable.
Assemblies concentrated in auditory areas and in visual areas, for example, can overlap in the frontal cortex, the hippocampus, and other central areas, linking visual and auditory inputs together with memories into a single perception. For years, this view remained the nearly heretical view of a small group of researchers, but in the 1990s this has begun to change. This growing evidence became clear at a major international workshop in 1997, at Sde Boker, Israel. Yuste's own work is part of that body of evidence. He is developing a new technique to actually see neurons in action, using fluorescence.