Expediting Creation of a Brain Map
A Korean scientist in the United States has come up with a way that can produce a “transparent brain” 100 times faster than before.
Prof. Chung Kwang-hun of the Massachusetts Institute of Technology (MIT), who is credited with developing an innovative technology to produce a transparent brain in 2013, has upgraded his technology, which is believed to play a significant role in completing a human brain map.
In 2013, Chung, then a postdoctoral researcher at Stanford University, developed a process called “CLARITY” that renders a mouse brain transparent. He extracted lipids from the brain and replaced them with a hydrogel, which is built from within the brain itself. Lipids are fatty molecules that help form cell membranes and give the brain much of its structure. The hydrogel leaves the brain’s three-dimensional complexity of fine wiring and molecular structures completely intact.
This time, Chung has developed “ELAST,” a technology that can coat nerve cells and proteins with a fluorescent material 100 times faster than before. ELAST is expected to speed up the creation of a brain map, a project that has not been completed to date.
Chung announced the development of ELAST in Nature Method, an international scholastic journal, on May 19. ELAST shortens the time needed for 3-D imaging of cells or molecules of the brain or other large organs while making them robust enough to be tested for many years.
Normally, in order to observe a specific brain protein or cell in a hospital or laboratory, the brain is cut 0.02 millimeters thick, dyed with a fluorescent material, and put under a microscope for an observation.
Chung's ELAST technology is simple. The technology removes lipids from the brain and fills it with elastic polyacrylamide. Then the brain becomes transparent and a fine net structure is revealed. Proteins, neural networks, and DNAs are fixed to polyacrylamides with a network structure. He explained that the cells and molecules of the tissue are entangled in polyacrylamides, so they are not damaged in the process.
"We can reduce the thickness to a tenth while simultaneously doubling the width or length of brain tissues," the research team said. A transparent brain made in this way is stretched or pressured to reduce its thickness, which shortens the dying process.
Scientists have long wanted to see one whole brain without cutting it. When Chung published “CLARITY” in the world-class scientific journal “Nature” in 2013, it was considered a breakthrough as it used chemicals to make a transparent brain.
In 2016, Chung succeeded in enlarging a transparent brain four-fold. He said in the international journal Nature Biotechnology at the time that by making the brain of a mouse transparent and enlarging it more than four times, he could see connections of small nerve cells that were difficult to see before.