The pea-sized structures reached the same level of development as in a nine-week-old foetus, but are incapable of thought.
The study, published in the journal Nature, has already been used to gain insight into rare diseases.
Neuroscientists have described the findings as astounding and fascinating.
The human brain is one of the most complicated structures in the universe.
Scientists at Institute of Molecular Biotechnology of the Austrian Academy of Sciences have now reproduced some of the earliest stages of the organ's development in the laboratory.