Infrared cerebrospinal fluid, dynamically produced by the LICOR Pearl LCD imaging system, allows us to assess the movement of the tracer on the surface of the brain as a surrogate measure of lymphatic metabolism. Credit: SA Keil et al

The glymphatic system facilitates fluid exchange in the central nervous system and cleanses dissolved waste. This anatomically organized movement occurs mainly during sleep and is maintained by astroglial nerve cells through water channels called aquaporins. These channels line the perivascular pathways and facilitate the exchange of cerebrospinal and interstitial fluid throughout the brain.

Glymphatic dysfunction has been implicated in many pathological conditions, including Alzheimer’s disease, traumatic brain injuries and strokes. Existing methods for assessing glymphatic function have been complex. Dynamic techniques such as 2-photon microscopy and contrast enhancement magnetic resonance imaging Imaging (MRI) requires expensive instruments and certain technical skills, however they have other limitations. For example, 2-photon microscopy cannot reliably access deeper areas of the brain. A more easily implemented and widely used method of fluorescent imaging based on sections allows you to evaluate only images of one point in time, so to obtain an overview in time requires a lot of animals and a lot of effort.

To meet the need for combined dynamic imaging and histological evaluation in glymphatic studies, a team of researchers from the U.S. Department of Veterans Affairs (VA) Puget Sound and the University of Washington (UW) in Seattle recently developed a simple and new paradigm measure as a paradigm. the flow of glymphatic in the brain. As reported in Neurophotonics, the technique uses a widely available infrared (IR) imaging system for small animals (LICOR Pearl) to produce a sensitive dynamic surrogate measure of lymphatic metabolism. It does this by tracking the spread of the LCD tracer cerebrospinal fluid real-time over the surface of the cerebral cortex of a live mouse.

The technique allows to measure the temporal dynamics of glymphatic functions, as well as the ability to follow fluorescent analysis based on the gold standard and histological evaluation to simultaneously visualize the resolution of deeper structures. This approach allows us to evaluate both dynamic and structural ideas in parallel. The technique works great for studies involving mice, but not for larger animals such as rats, due to the size of the imaging platform and the thicker skulls of large rodents.

Relying on affordable and widely available equipment, the team is easy to distribute and widely distributed. According to senior study author Jeffrey Ilif, deputy director of research at VISN20 Mental Illness, Research, Education and Clinical Health Center VA Puget Sound and Professors Arthur J. and Marcela McCaffrey on Alzheimer’s at UW School. medicine, “The glymphatic field is expanding rapidly in both the clinical and preclinical fields. We hope that this simple, inexpensive approach will allow rigorous study of glymphatic biology within the reach of a wider, more diverse group of research groups and institutions.”

Waste management in the brain can shed light on dementia

Additional information:
Samantha A. Cale et al., Dynamic infrared visualization of cerebrospinal fluid inflow to the brain, Neurophotonics (2022). DOI: 10.1117 / 1.NF.9.3.031915

Provided by SPIE – International Society of Optics and Photonics

Citation: Infrared image to measure glymphatic function (2022, May 17) obtained May 17, 2022 from

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