The human brain is routinely described as the most complex object in the known universe. It might therefore seem unlikely that pea-size blobs of brain cells growing in laboratory dishes could be more than fleetingly useful to neuroscientists. Nevertheless, many investigators are now excitedly cultivating these curious biological systems, formally called cerebral organoids and less formally known as mini-brains. With organoids, researchers can run experiments on how living human brains develop—experiments that would be impossible (or unthinkable) with the real thing.
The cerebral organoids in existence today fall far short of earning the “brain” label, mini or otherwise. But a trio of recent publications suggests that cerebral-organoid science may be turning a corner—and that the future of such brain studies may depend less on trying to create tiny perfect replicas of whole brains and more on creating highly replicable modules of developing brain parts that can be snapped together like building blocks. Just as interchangeable parts helped make mass production and the Industrial Revolution possible, organoids that have consistent qualities and can be combined as needed may help to speed a revolution in understanding how the human brain develops.