Cerebral Organoids: Conscious Subjects or Zombies?

In 2011, at the Institute of Molecular Biotechnology in Vienna a postdoctoral researcher, Madeline Lancaster, inadvertently brought about the production of a brain organoid from human embryonic stem cells. The brain organoids neuroscientists can now grow consist of several million neurons. Brain organoids can be produced much as other 3D multicellular structures resembling eye, gut, liver, kidney and other human tissues have been built. By adding appropriate signaling factors, aggregates of pluripotent stem cells (which have the ability to develop into any cell type) can differentiate and self-organize into structures that resemble certain regions of the human brain. There's debate about exactly how and to what extent these so-called "mini-brains" resemble human brains. Yet, given considerable similarities with respect to their constitution, neural activity, and structure, cerebral organoids can be used as reliable models of human brains, which is advantageous for neuroscientists who have limited access to the human brain as it functions.