Such rhythmic waves linked to state of consciousness
From the WashU Newsroom…
If you keep a close eye on an MRI scan of the brain, you’ll see a wave pass through the entire brain like a heartbeat once every few seconds. This ultra-slow rhythm was recognized decades ago, but no one quite knew what to make of it. MRI data are inherently noisy, so most researchers simply ignored the ultra-slow waves.
But by studying electrical activity in mouse brains, researchers at Washington University School of Medicine in St. Louis have found that the ultra-slow waves are anything but noise. They are more like waves in the sea, with everything the brain does taking place in boats upon that sea. Research to date has been focused on the goings-on inside the boats, without much thought for the sea itself. But the new information suggests that the waves play a central role in how the complex brain coordinates itself and that the waves are directly linked to consciousness.
“Your brain has 100 billion neurons or so, and they have to be coordinated,” said senior author Marcus Raichle, MD, the Alan A. and Edith L. Wolff Distinguished Professor of Medicine and a professor of radiology at Mallinckrodt Institute of Radiology at the School of Medicine. “These slowly varying signals in the brain are a way to get a very large-scale coordination of the activities in all the diverse areas of the brain. When the wave goes up, areas become more excitable; when it goes down, they become less so.”
The study is published March 29 in the journal Neuron.
In the early 2000s, Raichle and others discovered patterns of brain activity in people as they lay quietly in MRI machines, letting their minds wander. These so-called resting-state networks challenged the assumption that the brain quiets itself when it’s not actively engaged in a task. Now we know that even when you feel like you’re doing nothing, your brain is still humming along, burning almost as much energy daydreaming as solving a tough math problem.