A closer look at unrecognized patterns in EEG brain data shows that putting the brain to work on a simple task can change those patterns, researchers at Washington University School of Medicine have found in a study published in the May 13 Neuron.

“We don’t yet know how to decode the information contained in these signals, but the fact that they’re such a large part of brain activity and that they can be modulated when you do a task suggests that they are going to be very important to understanding the brain,” says lead author Biyu Jade He, PhD, a postdoctoral fellow.

She studied data gathered from five patients with drug-resistant epilepsy. To treat these patients, surgeons temporarily implant grids of electrodes on the surface of the brain, allowing them to gather detailed EEG readings and pinpoint the source of the seizures for surgical removal.

Using a technique called nested-frequency analysis, she showed that the temporal connections between low-frequency brain waves and high-frequency brain waves are more extensive than previously realized, and that there are patterns of temporal organization in those irregular signals.

“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 suggests that there are patterns of temporal organization in those irregular signals. Those patterns may reflect important aspects of brain architecture and function.”

Next, scientists asked six patients with electrode implants to press a button either in response to a cue or at random time intervals that they chose. During these experiments, Biyu He identified changes in the power spectrum of this irregular brain activity in brain regions involved in performing the tasks.

More info: Washington University School of Medicine news