Part of what makes studying the human brain is that it is perhaps the most complex organ we know of, and it’s pretty hard to replicate that in the lab. Because we can’t just test out new drugs on people without knowing what they might do, we generally have to test them on animals like lab rats first. That can tell us a lot, but lab rats are not humans.

Enter a team of scientists in from the Genome Institute of Singapore (GIS), who have developed what are known as “mini-brains.” These are small groups of cells that replicate the human midbrain, which is responsible for hearing, eye movements, vision and body movements, and which is targeted by Parkinson’s disease and other disorders.

The mini-brains, which are grown from stem cells, mimic the development of the midbrain. They are only about 3 millimeters wide and have neurons that produce dopamine, a key neurotransmitter in motor functions such as walking and hand movements. The mini-brains also contain the pigment neuromelanin, which can degenerate in neurological illnesses such as Parkinson’s.

The mini-brains are structured the same as a human midbrain, with cells clustering together in layers and being electrically and chemically active.

With the new mini-brains, labs would have a much easier time testing drugs that might help people with Parkinson’s or other neurological diseases.

Another advantage of the mini-brains is that they could replace the animals currently used in neurological research. Rather than using animals, “we can now use these midbrains … instead to advance our understanding and future studies for [Parkinson’s disease], and perhaps even other related diseases,” said GIS Executive Director Prof. Ng Huck Hui.

Even the most promising treatment methods currently have years-long development cycles, from conception through to human testing. Advances in medical science such as the mini-brains might help to make that process faster, which will allow potentially lifesaving drugs to reach people with these illnesses in time to make a difference.