Neurobiology

The pacific Waves

Image result for ultra slow brain waves
Image source: davincimethod.com

Up until three weeks ago, everyone thought the brain quiets itself when it’s not involved in an activity. New research proves the contrary. Even when you think you’re not actively doing anything, your brain still hums along, using ‘as much energy daydreaming as solving a tough math problem’ (yeah, no wonder my brain got tired as I lay there contemplating – for an unusually long time btw – on what to wear the following days with matching accessories).

For years, scientists had overlooked the ultra-slow waves appearing in MRI data in the resting state as inherent noise. (MRI determines brain activity indirectly by ascertaining the stream of oxygen-rich blood over a period of seconds.)

“Your brain has 100 billion neurons or so, and they have to be coordinated,” said Marcus Raichle, MD. Raichle is senior author on the study and distinguished professor of Medicine and a professor of Radiology at the School of Medicine, Washington University. “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.” So, you can imagine the neuronal fireworks up in the brain when, for instance, you’re on the road driving.

Researchers in the study discovered that the ultra-slow waves spontaneously originated in a deep layer in mice brains and spread along a defined path. The waves amplified the electrical activity in each brain area they passed through. Neurons fired more fervently when a wave was around.

Another exciting finding was that these ultra-slow waves persisted under anesthesia BUT with the direction of the wave reversed. This dramatic change associated with the state of consciousness suggests the significance of ultra-slow waves in brain function. ‘If brain areas are thought of as boats bobbing about on a slow-wave sea, the choppiness and direction of the sea surely influences how easily a message can be passed from one boat to another, and how hard it is for two boats to coordinate their activity’ – extract from ScienceDaily article.

The practical implications of this study lie in the idea whether irregularities in the trajectory of ultra-slow waves could shed light on some differences noticed in MRI scans between healthy people and those with neuropsychiatric conditions like depression and dementia.

 

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