I like science fiction. Each work of SF opens a fascinating window on possible worlds. I remember an unpretentious but quite funny book for teenagers, where head transplants were possible, but reserved for the rich. A few years later, but in real life, an Italian researcher, Sergio Canavero, made headlines for his ethically reprehensible and scientifically dubious experiments.
Far from these transplant deliriums, research on the brain is advancing rapidly. Whether on the technological side, where artificial neural networks weave their web, or on the biological side. I was able to realize in The cross work carried out at the Institut Pasteur on cerebral organoids, 3D structures that reproduce part of the human brain and that are “grown” from stem cells.
These organoids have an electrical activity like real neurons, but, isolated in small plastic boxes, they stop developing after a certain time and do not exceed a few millimeters. Last week, a study published in the journal Nature describes an additional stage. Since these organoids do not grow in the absence of vascularization, what happens if we implant them in the heads of animals?
Ethical issues
Teams from Stanford University therefore tried by transplanting organoids into the brains of developing rats. In the 70% of surviving rodents, human neurons formed synapses with rat neurons. The integration is complete. The work also shows that human neurons influence the behavior of rats. Stanford’s rodents did not become bakers, engineers or writers.
A commentary accompanying the study questions the ethical questions if the practice were to go further. So far, only one organoid has been transplanted, which represented only a small part of the tissues of the cortex. But tomorrow, will we be able to grow entire sections of the brain? Connect several different organoids together to form a quasi-brain? And also, what would be the impact of this foreign body on the rodent?
Waiting for the uprising of the rats
While waiting for the rats to rise, other researchers, from Australian start-up Cortical Labs this time, trained 800,000 human neurons to play Pong, the arcade game where you have to send a ball from one side to the other. You will tell me, I have neurons and I know how to play Pong, nothing revolutionary. But these neurons are in a box, and were grown from mouse embryonic cells and human stem cells.
“DishBrain” must now be exposed to alcohol and various substances to test the effects on his reactions. The researchers put forward an alternative to animal experiments, which is also more reliable because it would better reproduce the human brain. Can’t wait to read the next fiction – sorry, study – which will explain how alcoholic neurons were grafted into rats who developed an Atari console and happily play Pong.