ScienceDaily reports (here) on the work of B. He and group on the noise that is discarded from EEGs when the dominant waves such as gamma, theta etc. are recorded. They feel it must contain valuable information.

“These temporal connections reach outside of the domains of periodic brain waves that neuroscientists study and into the irregular, arrhythmic brain activity that we discard,” she explains. “This (research) suggests that there are patterns of temporal organization in those irregular signals. Those patterns may reflect important aspects of brain architecture and function.”…

“The noisy activity of the brain at rest and in the background when we perform tasks actually represents the majority of what the brain is really doing” Raichle says. “We know this to be the case when we measure the cost of running the brain and find that this background activity accounts for most of it. Biyu’s (He) pioneering research is a major step forward in helping us understand how this background activity is organized.”

Analysis of this noise shows that it has a pattern that is common in natural systems. Signals produce a regular pattern: a diagonal line on the results graph that goes from the upper left (high-power, low-frequency brain waves) to the lower right (low-power, high-frequency brain waves). This power spectrum changes with various activities of the brain, a source of potential information that has not been used to date.