Look inside the living: how scientists study the brain and why

New brain imaging technique

• What have scientists created?

Researchers have developed a new technique that

allows you to get microscopicfluorescent images deep in the brain. It is four times the limit imposed by light scattering. Fluorescence microscopy is often used to visualize the molecular and cellular details of the brain in animal models of various diseases. However, until now, it has been limited to small volumes and highly invasive procedures due to the intense light scattering from the skin and skull.

New method - diffuse optical imaginglocalization (diffuse optical localization imaging, DOLI). It takes advantage of near infrared infrared (NIR-II) spectroscopy from 1000 to 1700 nanometers. It is this that provides the least scattering of light.

• What for?

Visualization of biological dynamics in an undisturbed environment, deep in a living organism, is necessary for understanding the complex biology of living organisms and the development of diseases.

3D fluorescence microscopy was performed completely non-invasively with capillary resolution in the adult mouse brain, effectively covering a field of view of about 1 centimeter.

A new brain imaging technique allows images of the vasculature deep in the brain of mice.

Providing the possibility of optical observations withhigh resolution in deep living tissue is a long-standing goal in biomedical imaging, the researchers note. The new development will be useful for studying neural activity, microcirculation, neurovascular interaction and neurodegeneration.

Activating neurons deep in the brain

• What have scientists created?

American scientists from WashingtonThe University of St. Louis has developed a new technique for brain stimulation using focused ultrasound that can turn certain types of neurons on and off in the brain and precisely control motor activity without implanting a surgical device.

The study showed the success of ultrasound for deep stimulation of neurons for the first time.

Scientists have placed a special design,containing TRPV1 ion channels to genetically selected neurons. They then created a small burst of heat using focused, low-intensity ultrasound to select neurons in the brain through a wearable device. The heat, just a few degrees above body temperature, activated the TRPV1 ion channel. Ultimately, it acted like a switch to turn neurons on or off.

• What for?

Neurological disorders such as illnessParkinson's and epilepsy have had some success with deep brain stimulation. The problem is that they require the implantation of a surgical device. The new development will change the very approach to research in the field of neurobiology and will open up new methods for understanding and treating diseases of the human brain.

Photosynthesis, not in plants, but in the brain

• What have the scientists done?

Blocked blood vessels in the brainstroke patients prevent oxygen-rich blood from reaching the cells. This, in turn, leads to serious damage. Plants and some microbes produce oxygen through photosynthesis. What if there was a way to activate it in the brains of patients? Scientists have done exactly this with cells and mice using blue-green algae and special nanoparticles in their demonstration.

Blue-green algae such as Synechococcus elongatuspreviously studied for the treatment of deficiencyoxygen in the tissues of the heart and tumors through photosynthesis. But the visible light needed to trigger germs cannot penetrate the skull. Yes, of course, near infrared light can pass through bone, but it is not enough to directly activate photosynthesis.

Special nanoparticles used forimaging can absorb near infrared photons and emit visible light. Using them, scientists have developed a new approach that could someday be used for stroke patients by combining S. elongatus, nanoparticles and near infrared light in a new system of nanophotosynthesis.

Brain sections of mice treated withnano-photosynthetic therapy (right) have fewer damaged neurons shown in green than control mice (left). Credit: Adapted from Nano Letters 2021, DOI: 10.10.21 / acs.nanolett.1c00719.

Researchers have connected S. elongatus with neodymium nanoparticles that transforminfrared light penetrating into tissues at a visible wavelength. It is bacteria that use it for photosynthesis. Scientists have found that the nanophotosynthesis approach reduces the number of neurons that die after oxygen and glucose deprivation. They then injected bacteria and nanoparticles into mice with blocked cerebral arteries and exposed the mice to light. The therapy reduced the number of dying neurons, improved motor function in animals, and even helped new blood vessels begin to grow.

• What for?

According to the World Health Organization,5 million people die every year from strokes worldwide. Millions more survive, but they often remain with disabilities, such as problems with speech, swallowing or memory. The most common cause is blockage of blood vessels in the brain, and the best way to prevent permanent brain damage from this type of stroke is to dissolve or remove the blockage with surgery as soon as possible. However, these options only work for a short time after a stroke and can be dangerous.

The nanophotosynthesis method solves this problem.

While the drug is still in animal testing, it promises to someday move to human clinical trials, the researchers say.

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