A study published in Cell Stem Cell this month concluded that they can. Using brain organoids made from human cells, a team led by Dr. Han-Chiao Isaac Chen at the University of Pennsylvania transplanted the mini-brains into adult rats with substantial damage to their visual cortex—the area that supports vision.
In just three months, the mini-brains merged with the rats’ brains. When the team shone flashing lights for the animals, the organoids spiked with electrical activity. In other words, the human mini-brain received signals from the rats’ eyes.
It’s not just random noise. Similar to our visual cortex, some of the mini-brain’s neurons gradually developed a preference for light shone at a particular orientation. Imagine looking at a black and white windmill blow toy as your eyes adjust to the different moving stripes. It sounds simple, but the ability of your eyes to adjust—dubbed “orientation selection”—is a sophisticated level of visual processing that’s critical to how we perceive the world.
