American researchers say they’ve performed what they believe is the first ever human-to-human brain interface, where one person was able to send a brain signal to trigger the hand motions of another person.

"It was both exciting and eerie to watch an imagined section from my brain get translated into actual action by another brain," said Rajesh Rao, a professor of computer science and engineering at the University of Washington, in a statement.

Previous studies have done brain-to-brain transmissions between rats and one was done between a human and a rat.

Rao was able to send a brain signal through the internet – utilizing electrical brain recordings and a form of magnetic stimulation – to the other side of the university campus to his colleague Andrea Stocco, an assistant professor of psychology, triggering Stocco’s finger to move on a keyboard.

"The internet was a way to connect computers, and now it can be a way to connect brains," said Stocco. "We want to take the knowledge of a brain and transmit it directly from brain to brain."

On Aug. 12, Rao sat in his lab with a cap on his head. The cap had electrodes hooked up to an electroencephalography machine, which reads the brain’s electrical activity. Meanwhile, Stocco was at his lab across campus, wearing a similar cap which had a transcranial magnetic stimulation coil place over his left motor cortex – the part of the brain that controls hand movement.

Rao looked at a computer and in his mind, he played a video game. When he was supposed to fire a cannon at a target, he imagined moving his right hand, which stayed motionless. Stocco, almost instantaneously, moved his right index finger to push the space bar on the keyboard in front of him.

Only simple brain signals, not thoughts

"This was basically a one-way flow of information from my brain to his," said Rao.

The project utilized two basic technologies:

Electroencephalography, or EEG, which is used by medical professionals to record brain activity non-invasively from the scalp.

TMS, or transcranial magnetic stimulation, which is a way of non-invasively delivering stimulation to the brain through the scalp.

Key to the project was the computer code, created by a group of computer undergraduates, which translated Rao’s brain signals into a command for Stocco’s brain.

Rao says the breakthrough has a lot of possibilities but for now, it’s only about channelling simple brain signals and not actual thoughts.

Chantel Prat, a research partner in the experiment and assistant professor at the Washington university’s Institute for Learning & Brain Sciences, cautions people against overestimating the technology.

"There’s no possible way the technology that we have could be used on a person unknowingly or without their willing participation," she said in a release.

Plans are to conduct the same experiment on a larger pool of people and to see if more complex information can be transmitted from one brain to another.