Fluorescence microscopy validates that sleep position affects how the brain clears waste

Stony Brook University (New York) researchers used dynamic contrast magnetic resonance imaging (MRI)—with validation by fluorescence microscopy—to image the brain's glymphatic pathway, a complex system that clears wastes and other harmful chemical solutes from the brain. In doing so, they discovered that a lateral (side) sleeping position is the best position to most efficiently remove waste from the brain. In humans and many animals, the lateral sleeping position is the most common one. The buildup of brain waste chemicals may contribute to the development of Alzheimer’s disease and other neurological conditions.

The brain’s glymphatic pathway clears harmful wastes, especially during sleep. This lateral position could prove to be the best position for the brain-waste clearance process
The brain’s glymphatic pathway clears harmful wastes, especially during sleep. This lateral position could prove to be the best position for the brain-waste clearance process.

Helene Benveniste, MD, Ph.D., the study's principal investigator and a professor in the Departments of Anesthesiology and Radiology at the Stony Brook University School of Medicine, has used dynamic contrast MRI for several years to examine the glymphatic pathway in rodent models. The method enables researchers to identify and define the glymphatic pathway, where cerebrospinal fluid (CSF) filters through the brain and exchanges with interstitial fluid (ISF) to clear waste, similar to the way the body’s lymphatic system clears waste from organs. It is during sleep that the glymphatic pathway is most efficient. Brain waste includes amyloid β (amyloid) and tau proteins, chemicals that negatively affect brain processes if they build up.

In the study, Benveniste and colleagues used a dynamic contrast MRI method along with kinetic modeling to quantify the CSF-ISF exchange rates in anesthetized rodents’ brains in three positions—lateral (side), prone (down), and supine (up).

Helene Benveniste, MD, Ph.D., and Hedok Lee, Ph.D., analyzed the glymphatic pathways of rodent models to assess how body posture affects the clearance of brain waste
Helene Benveniste, MD, Ph.D., and Hedok Lee, Ph.D., analyzed the glymphatic pathways of rodent models to assess how body posture affects the clearance of brain waste.

“The analysis showed us consistently that glymphatic transport was most efficient in the lateral position when compared to the supine or prone positions,” said Dr. Benveniste. “Because of this finding, we propose that the body posture and sleep quality should be considered when standardizing future diagnostic imaging procedures to assess CSF-ISF transport in humans and therefore the assessment of the clearance of damaging brain proteins that may contribute to or cause brain diseases.”

Benveniste and first author Hedok Lee, Ph.D., assistant professor in the Departments of Anesthesiology and Radiology, developed the safe posture positions for the experiments. Their colleagues at the University of Rochester (New York), including Lulu Xie, Rashid Deane, and Maiken Nedergaard, Ph.D., used fluorescence microscopy and radioactive tracers to validate the MRI data and to assess the influence of body posture on the clearance of amyloid from the brains.

A study by Stony Brook University researchers suggests that sleeping on one’s side, as opposed to other positions such as on one’s back or stomach, may more effectively remove brain waste, a contributor to the development of neurological disorders
A study by Stony Brook University researchers suggests that sleeping on one’s side, as opposed to other positions such as on one’s back or stomach, may more effectively remove brain waste, a contributor to the development of neurological disorders.

“It is interesting that the lateral sleep position is already the most popular in human and most animals—even in the wild—and it appears that we have adapted the lateral sleep position to most efficiently clear our brain of the metabolic waste products that built up while we are awake,” says Nedergaard. “The study therefore adds further support to the concept that sleep subserves a distinct biological function of sleep and that is to ‘clean up’ the mess that accumulates while we are awake. Many types of dementia are linked to sleep disturbances, including difficulties in falling asleep. It is increasing acknowledged that these sleep disturbances may accelerate memory loss in Alzheimer’s disease. Our finding brings new insight into this topic by showing it is also important what position you sleep in,” she explains.

Benveniste cautioned that while the research team speculates that the human glymphatic pathway will clear brain waste most efficiently when sleeping in the lateral position as compared to other positions, testing with MRI or other imaging methods in humans are a necessary first step.

Full details of the work appear in the Journal of Neuroscience; for more information; please visit http://dx.doi.org/10.1523/jneurosci.1625-15.2015.

Follow us on Twitter, 'like' us on Facebook, connect with us on Google+, and join our group on LinkedIn

Get All the BioOptics World News Delivered to Your Inbox

Subscribe to BioOptics World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now
Related Articles

New bioimaging technique offers clear view of nervous system

Scientists at Ludwig-Maximilians University have developed a technique for turning the body of a deceased rodent entirely transparent, revealing the central nervous system in unprecedented clarity....

Fluorescent jellyfish proteins light up unconventional laser

Safer lasers to map your cells could soon be in the offing -- all thanks to the humble jellyfish. Conventional lasers, like the pointer you might use to entertain your cat, produce light by emittin...

Microscope detects one million-plus biomarkers for sepsis in 30 minutes

A microscope has the potential to simultaneously detect more than one million biomarkers for sepsis at the point of care.

Eye test that pairs two in vivo imaging methods may detect Parkinson's earlier

A low-cost, noninvasive eye test pairs two in vivo imaging methods to help detect Parkinson's before clinical symptoms appear.

BLOGS

Neuro15 exhibitors meet exacting demands: Part 2

Increasingly, neuroscientists are working with researchers in disciplines such as chemistry and p...

Why be free?

A successful career contributed to keeping OpticalRayTracer—an optical design software program—fr...

LASER Munich 2015 is bio-bent

LASER World of Photonics 2015 included the European Conferences on Biomedical Optics among its si...

White Papers

Understanding Optical Filters

Optical filters can be used to attenuate or enhance an image, transmit or reflect specific wavele...

How can I find the right digital camera for my microscopy application?

Nowadays, image processing is found in a wide range of optical microscopy applications. Examples ...

CONNECT WITH US

            

Twitter- BioOptics World

Copyright © 2007-2016. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS