Researchers have mapped tiny fragments of the human brain on an unprecedented scale, showing each brain cell, or neuron, and the complex networks they form with other cells in vivid detail.
This groundbreaking brain map, constructed by researchers at Harvard University and Google, shows approximately 57,000 neurons, 9 inches (230 millimeters) of blood vessels, and 150 million synapses, or connections between neurons. It became clear.
Dr. Jeff LichtmanThe Harvard molecular and cell biology professor who co-led the 10-year project said he couldn't believe it when he first saw the detailed map. “I've never seen anything like this before,” he told his Live Science.
The human brain is a very complex organ; Approximately 170 billion cells, including 86 billion neurons. Researchers have previously used magnetic resonance imaging (MRI) to peer into the brain on a millimeter scale. And more recently, advanced microscopy techniques have revealed details on a much smaller scale, deepening our understanding of the inner workings of the brain.
Related: Most detailed human brain map to date includes 3,300 cell types
Now, these microscopy methods and artificial intelligence Lichtman and his colleagues used a system called machine learning (AI) to create 3D maps of parts of the brain at the scale of nanometers, or one millionth of a millimeter. It displays images of organs at the highest resolution ever achieved by scientists.
The resulting cell atlas, published in the journal science May 9th too available to scientists online.
This map shows part of a tiny brain, about 1 cubic millimeter in volume (smaller than a grain of rice). The entire adult brain is a million times larger.
The brain fragments were taken from a 45-year-old woman who underwent brain surgery to treat epilepsy. Doctors removed the section from the cerebral cortex. outermost part of her brain. The researchers fixed the samples with preservatives and then stained them with heavy metals to reveal the cells. The tissue was then embedded in resin and cut into more than 5,000 slices about 30 nanometers thick.
“This is about one-thousandth the thickness of a human hair,” Lichtman said. The researchers scanned each slice with a high-speed electron microscope, which uses multiple electron beams to illuminate the cells within the sample. The microscopy data was then sent to Google for further analysis using AI.
Google researchers used a machine learning model to identify the same object in different microscopic images and created a 3D rendering of every object in every image. The renderings were then pieced together electronically to reconstruct the entire sample in her three dimensions. The final 3D map contains a whopping 1.4 petabytes, or 1 million gigabytes.
“The amount and complexity of data generated in this project required Google's ability to develop cutting-edge machine learning and AI algorithms to reconstruct the 3D connectome.” biren jainismA senior staff scientist at Google who co-led the project told Live Science via email.
Scientists' detailed map contains some surprises. For example, they discovered that some of the wires, or axons, coming out of neurons form knots, forming spirals that Jains describe as “mysterious but beautiful.” The researchers also discovered rare connections between neurons, where a single axon connects to up to 50 synapses.
“We are still investigating the function of these connections, but they may explain how very fast responses and very important memories are encoded,” Jain told Live Science.
It remains to be seen whether the whorls and super-strong synapses have anything to do with epilepsy in tissue donors, or whether they are also found in the brains of people without symptoms, Lichtman noted. He added that the research team is currently examining brain tissue from Parkinson's patients, which could begin to solve the problem.
He added that brain tissue samples taken from two people are unlikely to look exactly the same, as the way the brain is wired depends on individual experience.
The researchers then aim to map the entire mouse brain, which is 500 times larger than this human brain sample. They start with the hippocampus, a key area for learning and memory.
“We have already begun an ambitious task,” Lichtman said.
Have you ever wondered why? Some people gain muscle more easily than others. or Why do freckles stand out in the sun?? Please send us your questions about how the human body works. community@livescience.com You may be able to see the answer to your question on the website by using the subject line “Health Desk Q''.