Human mini-brains grown from stem cells in the lab, have shown electrical activity on a par with that of premature, newborn baby brains.
Researchers said that the electrical patterns generated by their nine-month-old 'brains-in-a-dish' were similar to that of readings taken from premature babes. This is the first time such activity has been recorded in a lab model.
'We couldn't believe it at first - we thought our electrodes were malfunctioning,' said co-senior author Dr Alysson Muotri at the University of California San Diego School of Medicine. 'Because the data were so striking, I think many people were kind of sceptical about it, and understandably so.'
The brain organoids were constructed using human iPS (induced pluripotent stem) cells. The team grew them on multi-electrode arrays so that they would be able to measure any cellular electrical activity. The researchers compared the mini-brains electrical outputs with EEG (electroencephalogram) readings from 39 premature babies (born between 24 and 38 weeks) and for several weeks after birth.
The mini-brains appeared to follow a similar pattern and level of electrical activity – with less quiet time and more electrical impulses as they aged.
'It's a very solid and incredibly important piece of research,' Dr Jeantine Lunshof at the Wyss Institute for Biologically Inspired Engineering in Boston, Massachusetts, told STAT. 'But it would be wrong to say that these organoids are baby brains. There is a lot more going on in real human brains than EEGs measure.'
The researchers are also cautious about extrapolating their results. 'They are far from being functionally equivalent to a full cortex, even in a baby,' said Dr Muotri. 'In fact, we don't yet have a way to even measure consciousness or sentience.'
The work was published in Cell Stem Cell.