In a new study, researchers suggest that tonight while you sleep, something amazing will happen within your brain.
Your neurons will go quiet. A few seconds later, blood will flow out of your head. Then, a watery liquid called cerebrospinal fluid (CSF) will flow in, washing through your brain in rhythmic, pulsing waves.
The study is the first to illustrate that the brain’s CSF pulses during sleep, and that these motions are closely tied with brain wave activity and blood flow.
This research may also be the first-ever study to take images of CSF during sleep.
It will one day lead to insights about a variety of neurological and psychological disorders that are frequently associated with disrupted sleep patterns, including autism and Alzheimer’s disease.
The research was conducted by a team from Boston University.
Earlier studies have suggested that CSF flow and slow-wave activity both help flush toxic, memory-impairing proteins from the brain. As people age, their brains often generate fewer slow waves.
In turn, this could affect the blood flow in the brain and reduce the pulsing of CSF during sleep, leading to a buildup of toxic proteins and a decline in memory abilities.
Although researchers have tended to evaluate these processes separately, it now appears that they are very closely linked.
The coupling of brain waves with the flow of blood and CSF could provide insights about normal age-related impairments as well.
As their research continues to move forward, the team has another puzzle they want to solve: How exactly are our brain waves, blood flow, and CSF coordinating so perfectly with one another?
One explanation may be that when the neurons shut off, they don’t require as much oxygen, so blood leaves the area.
As the blood leaves, pressure in the brain drops, and CSF quickly flows in to maintain pressure at a safe level.
The lead author of the study is Laura Lewis, a BU College of Engineering assistant professor of biomedical engineering.
The study is published in Science.
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