For the first time, researchers have observed an electrical activity in brains created in the laboratory. It was close to that recorded in premature babies.
This is likely to cause many concerns about bioethics. For the first time, researchers have succeeded in creating mini-brains in the laboratory showing electrical activity similar to that of a human. More specifically, a premature human baby. The results, which had already been presented at a conference a few months ago, appeared on August 29 in the journal Cell Press. If this discovery is uncomfortable for many scientists, it could open many possibilities for studying the early development of brain disorders.
Here, researchers have developed laboratory-grown brains, called organoids, from human pluripotent stem cells that can differentiate into many different cell types. They pushed them to develop cells in the cerebral cortex, responsible for memory, cognition or sensory processing. After two months of cultivation, they realized that an electrical activity had appeared. After six months, this signal was "constant" and very energetic. The brain activity was not as organized as that of an adult but had characteristics in common with that of premature babies.
"The level of neuronal activity we observe is unprecedented in vitro," says neuroscientist Alysson Muotri of the University of California, San Diego, USA, who initiated the study. The researcher has been developing organoids for years, but this is the first time that he and his team have noticed brain activity of this kind.
A step in the understanding of brain development?
"Although the activity of the network from organoids does not exhibit all the temporal complexity observed in adults, the model of alternating periods of rest and synchronized events in a network is similar to the electrophysiological signatures present in electroencephalography (EEG of the premature infant, "write the researchers.
Thus, if organoids are not as developed as human brains (no brain wave comparable to that of a real brain has been recorded), they could represent a step in the understanding of brain development. Ultimately, they could be used in the study of a large number of diseases whose mechanisms remain relatively unknown such as autism, Alzheimer's or epilepsy.
Results that raise major concerns
"Although we do not claim the functional equivalence between organoids and a complete neonatal cortex, the current results represent the first step towards an in vitro model that captures part of the complex spatio-temporal oscillatory dynamics of the human brain," conclude scientists who want to further develop their "mini brains" to see if they continue to mature.
If this research is impressive, it worries many scientists who are afraid of developing a consciousness in the laboratory. Their fear is to arrive at what a cerebral oragnoid imagines alive as a human being. "The closer they get to the premature baby, the more they should worry," said Christoph Koch, neuro-scientist at the Allen Institute for Brain Science in Seattle, USA, at the journal. Nature in November 2018.
But since organoids have been designed to have certain brain deficiencies, researchers are not worried yet. However, if some began to show signs of consciousness, they will consider stopping the project, they ensure in the hope of calming anxieties.