The team grew hundreds of pea-sized brains from stem cells for 10 months and monitored their neural activities using electrodes. The organoids started producing bursts of brain waves after about two months – similar to what we see in the brains of pre-term babies.

As the mini-brains continued to grow, they produced brain waves at different frequencies, and the signals appeared more regularly, suggesting the neurons were developing more connections and creating a neural network

The study, published August 29 in the journal Cell Stem Cell, could help scientists better understand human brain development.

“The level of neural activity we are seeing is unprecedented in vitro,” says AlyssonMuotri, a biologist at the University of California, San Diego. “We are one step closer to have a model that can actually generate these early stages of a sophisticated neural network.”

“It might be that in the future, we will get something that is really close to the signals in the human brains that control behaviours, thoughts, or memory,” Muotri says. “But I don’t think we have any evidence right now to say we have any of those.”

Looking forward, the team aims to further improve the organoids and use them to understand diseases associated with neural network malfunctioning, such as autism, epilepsy, and schizophrenia.

Professor Bronwen Connor from University of Auckland’s Centre for Brain Research says the research presents an exciting and significant advancement in the field of neuroscience.

“Trujillo et al. have expanded the capability of brain organoids and demonstrated that as the cells within the brain organoid mature, they start to produce electrical activity similar to that seen in the embryonic and pre-term brain. This is exciting as it further demonstrates that brain organoids closely model the developing human brain and are therefore able to be used to further investigate human brain development as well as study neurodevelopmental disorders such as autism. This capability will greatly enhance the ability to identify and develop new treatment strategies for currently untreatable neurodevelopmental conditions.”

However Professor Jing-Bao Nie from University of Otago’s Centre for Bioethics takes a different view.

“What is science ultimately for? How can unintended harmful and evil consequences be prevented in the pursuit of ‘good’? Should science have a limit? These are the questions that must not be resolved by scientists alone, but rather moderated by the inputs of each and every citizen.”


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