Scientists at ETH Zurich have broken new ground by generating over 400 types of nerve cells from stem cells in the lab, far surpassing previous efforts that produced only a few dozen. By systematically experimenting with combinations of morphogens and gene regulators, the researchers replicated the vast diversity of neurons found in the human brain. This breakthrough holds major promise for studying neurological diseases like Alzheimer’s and Parkinson’s, creating more accurate models for drug testing, and eventually even enabling neuron replacement therapies.