After growing in culture for a few months, the mini-brains produced rhythmic neural activity that strengthened over time.

Inserting human “mini-brains” into rodents has the potential to broaden scientists’ understanding of neurological disease, but raises quandaries about consciousness.

Mini-brains can be grown in culture or printed.

Brain organoids engineered to carry the genetic material could reveal how our brains are similar to and different from those of our closest relatives.

The organs showed neural activity for up to 36 hours, adding fuel to discussions about the ethics of future neuroscientific research.

After implantation, the tissue developed blood vessels and became integrated into neuronal networks in the animals’ brains.

More-sophisticated structures lend new insight into how Zika attacks the developing brain.

Scientists grew organoids that mimic human fetal brains and infected them with the Zika virus to model its neurological effects.