For the first time, brain tissue grown in a laboratory showed spontaneous electrical activity and was amazingly similar to human brain activity. In particular, it is similar to the brain activity of premature babies.
This is a great discovery that opens up possibilities for investigating the early development of brain disorders.
Some scientists also feel restrained.
These brain-grown brains are called organoids. simplified miniature versions of organs cultured for research in a laboratory, e.g. For testing drug responses or developing cells under certain adverse conditions.
reviewed and published in Cell Stem Cell.
"The level of neuronal activity we observe in vitro is unprecedented," says neuroscientist Alysson Muotri of the University of California at San Diego.
"We are one step closer to having a model that can actually create these early stages of a sophisticated neural network."
Muotri has been developing brain organoids in his laboratory for several years, but this is the first time that he and his tea I have seen something like the activity of the human brain.
They bred the organoids in question from human pluripotent stem cells or stem cells, which can become any other type of cell. They caused these "gaps" to develop into cells that make up the cerebral cortex, which is responsible for really important things like memory, perception, perception, thinking, and sensory processing.
You can see a cross-section of one of the organoids below.
Hundreds of these little brains were bred in a culture over a 10-year period, with tests to ensure that the right genes have been expressed for brain development. They also continuously monitored the organs with electroencephalography (EEG).
After six months as reported by Nature brain cells showed a very energetic brain activity – much more so than any other team before.
According to the analysis, the activity did not resemble the organized, predictable brain activity of an adult. But it seemed to be a different kind of brain activity. It had patterns in common with the chaotic outbreaks of synchronized brain activity in premature babies.
"While the network activity of organoids does not show the full temporal complexity observed in adults, the pattern of alternating rest periods and network-synchronized events is comparable to electrophysiological signatures in preterm neonatal EEG," the researchers wrote.
It was not exactly the same. However, a machine learning model trained on premature EEG signatures has been able to identify many common features with a normal development schedule. In the last 28 weeks, the organoids appeared to be on a similar developmental path as a premature baby of the same age.
The brain's organoids do not quite resemble the parts of the human brain – they are not just downsized and simplified They also have no other brain regions to connect to. They have also been engineered to lack a protein that is essential for the normal function of neurons.
But they could be a step towards a better understanding of brain development, as the premature baby's brain is not easy to find and the brain of adults is notoriously complicated.
"We do not claim functional equivalence" The current results represent the first step towards an in vitro model that captures part of the complex spatio-temporal dynamics of the human brain, "the researchers write. But others are genuinely concerned about the nearness of consciousness development in a tub culture in a laboratory, so far none of the brains show any signs of consciousness, but as the experiment progresses, they continue to evolve the brain cells to see if they continue to mature.
This could be a possibility. "The closer they get to the premature baby, the more they should be worried," said neuroscientist Christof Koch of The Allen Institute for Brain Science in Seattle Nature as early as November 2018, when the research results were presented on
given the careful development d he said, the researchers are not worried about the organoids to inhibit normal function at this time. However, when there are signs of consciousness, they consider the attitude of the project.
The study was published in Cell Stem Cell
our coverage of the pre-printed presentation of this work in November 2018.