A mini-brain, despite what it sounds like, is not the brain of a mouse or any other small creature, nor is it a pejorative for someone you think may be a little daft. It is, in fact, a small sphere of central nervous system tissue that is capable of forming electrically active neural connections, or synapses, although it is not capable of thought. These could become an essential addition to neuroscience research as scientists can expose them to drug compounds, infuse them with stem cells, or even subject them to electric currents to see how they behave. This is certainly safer than operating and experimenting on the real thing.

A new study from Brown University, published in Tissue Engineering: Part C, describes how to manufacture these small balls of tissue with relative ease and for a low cost: $0.25 (£0.16) to be precise. Using a small sample of living tissue from a common rodent, the desired cells are gathered and concentrated together by spinning the tissue in a machine called a centrifuge. These concentrated cells are then seeded – spreading them into a fertile, sterile area – within a spherical mould.

After the first day, brain tissue begins to form. Within a few weeks, the mini-brains have grown to almost a third of a millimeter in diameter, containing complex, 3D neural networks.

Although these are not the first mini-brains to be developed, they require far fewer steps than previous methods and use inexpensive, readily-obtainable material. In addition, the methods these researchers have developed produce mini-brains with important properties, allowing them to be experimented on using a variety of biomedical techniques.

For example, the mini-brains contain a range of different cells, including both inhibitory and excitatory neurons. Their 3D construction allows for realistic neurological geometry to develop and they can exist for up to a month without degrading. They also have a similar number of cells per cubic millimeter as the rodent species from which they are derived, providing the researchers with a “realistic” neurological network to work with.

^{A mini-brain created at Brown University. Brown Life Sciences/Vine.}

As mentioned, mini-brains have been developed before. A 2013 study in Nature described a process wherein pea-sized structures of neurons matching that of the synaptic development of a nine-week-old human fetus were grown from either adult or embryonic skin cells. Multiple parts of the human brain can be developed using this process, including the part of the embryo that will eventually grow into the section of the brain responsible for consciousness (cerebral cortex) and the spinal cord. However, this process uses materials far less accessible than those used in the recent study, led by Dr Yu-Ting Dingle.

This new technique of rapidly generating mini-brains will allow researchers to alter their development and scrutinize the effects of their tampering within a just a few weeks, allowing them to investigate specific neurological disorders over a short time period.