Electrical signs of activity in assemblies of neurons: compound field potentials as objects of study in their own right.

A case is made for the study of evoked and ongoing brain potentials as signs of activity in organized assemblies of neurons. Whereas the study of single unit activity, usually spike activity only, will continue to be a major window onto brain function, it cannot explain or predict much of the compound field potential recorded from assemblies even those with small populations via semimicroelectrodes. We need as many different windows as we can look through; each gives insight on a different set of integrative mechanisms. Evoked and ongoing potentials reveal a number of features and have advantages for a variety of questions not otherwise as readily addressed.