Scientists working with the Johns Hopkins School of Public Health have made a fascinating discovery. According to a report from The Guardian, researchers have grown ‘mini-brains’ in petri dishes that could one day revolutionize drug testing.

Yes, you heard that right. Tiny balls of human brain cells no bigger than the tip of a pen have been grown to show electrical activity, which could lead to new insights about how the brain responds to certain stimuli. This has huge implications for drug testing and may even eliminate the need for animals in medical research altogether.

The team, led by Professor Thomas Hartung from Johns Hopkins University, presented their findings at the conference of the American Association for the Advancement of Science. Professor Hartung said that each ball of cells represents a brain that is only about two months old. The researchers noticed that the neurons in the cultures began sending electrical signals to each other all on their own.

“It’s starting to produce a primitive type of ‘thinking,’” said the professor. “Obviously there’s no input or output. It is meaningless electrical activity but the neurons are trying to communicate with each other.”

Believe it or not, this isn’t the first time scientists have grown ‘mini-brains’ in a laboratory. The first ones were developed in December of 2013, and a team of Harvard scientists conducted a promising study using human brain cell cultures to research Alzheimer’s disease in 2014. This, however, is the first time that scientists have come up with a standardized process for creating ‘mini-brains,’ meaning that they can produce hundreds of cultures at a time.

So how can the discovery help researchers test new drugs? By reading the electrical activity in the cultures’ neurons with an EEG-like device, scientists can see how different chemicals affect the health and functions of the cells. They respond just like a neuron in an actual person’s brain would, and researchers wouldn’t need to continue to test drugs on animals if the new method catches on.

The research team hopes that the new ‘mini-brains’ will help ongoing studies on Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, and autism.