A research team from the University of Hong Kong (HKU) Department of Electrical and Electronic Engineering (EEE) Imaging Technologies, in collaboration with the University of California, Berkeley (UC Berkeley), has provided an unprecedented video of an individual. Blood cells flow through the brain of an awake mouse.

This development gives neuroscientists tools to better understand the inner workings of the brain, especially at the level of individual blood vessels and how blood flow varies throughout the larger vascular network within the brain. Offers. Healthy and diseased brains (Alzheimer’s disease, stroke, etc.).

This achievement was reported in “Ultrafast Two-Photon Fluorescence Imaging of Cerebral Blood Circulation in the Mouse Brain in vivo,” recently published in the peer-reviewed Proceedings of the National Academy of Sciences.

The team’s microscope features ultrafast two-photon fluorescence imaging, which allows light to penetrate deeper into tissue and capture blood cells faster than other gold-standard microscopy techniques. Most other techniques work with one-photon fluorescence and are limited to capturing low-flow regimens in which the anesthetized animal is not moving due to the slow mechanism of the focus scanning His.

The two-photon imaging technique the team developed, on the other hand, can capture faster-moving streams, in this case red blood cells, even when the animal is awake and able to move somewhat. Red blood cell flow is an important cue for brain activity and is fueled by energy from the blood supply.

The interdisciplinary research team, including engineers and neurobiologists, was led by Professor Gina of the Department of Molecular and Cellular Biology at the University of California, Berkeley, and Professor Kevin Tzer of HKU EEE, who is also program director of the Biomedical Engineering Program.

“One of the main limitations of other brain-imaging techniques is image resolution. You can even capture individual blood cells, count them and trace their trajectory,” said Professor Tsia.

Images of the two approaches show the significant difference. With low-flow technology, blood flow resembles smudging and oozing. Images from two-photon fluorescence techniques are much more detailed, clearly showing individual cells moving at high speed.

In 2020, the research team first reported their success in recording millisecond electrical signals in neurons in awake mice using fast two-photon fluorescence techniques. With this latest output, they have pushed the possibilities of their technology. The same technology is being applied by Professor Tsia’s team to cancer screening by imaging cancer cells in the blood.

“The study of imaging individual blood cells in vivo is an extension of that work and shows that this technique can be extended to other types of neuroscience research, particularly cerebral hemodynamics, which is the dynamics of blood flow to the brain. ,” said Professor Tsia. Said.

Paper link:

“Ultrafast two-photon fluorescence imaging of cerebral blood circulation in the mouse brain in vivo” was recently published in the Peer-Reviewed Proceedings of the National Academy of Sciences, Vol. 119, No.23, 2022.

https://www.pnas.org/doi/10.1073/pnas.2117346119

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