Brain-to-brain communication was first demonstrated in humans back in August by Andrea Stocco and Rajesh Rao, neuroscientists at the University of Washington. The pair themselves served as the initial test subjects. Their system has now been thoroughly tested and, as described in a paper published last week on PLOS One, it's stable.
According to the researchers, knowing that their initial demonstration wasn't merely a fluke opens the door to all kinds of insanely futuristic research and applications. Knowing how to reliably transmit encoded motor function signals from one brain to another could lead to new advances in hyper-personalized neurorehabilitation, a new field that aims to help people who have suffered brain damage re-learn how to perform simple tasks like swallowing, for example, by stimulating the associated neurons.
A direct brain-to-brain interface (BBI) could also constitute "the ultimate test of neuroscientific theories," Stocco told me when I called him to get caught up on his group's most recent work.
"Right now we've reached a point where participants can just walk in, sit in the chair, and we can make this thing work," Stocco said. "The fact that this is stable opens up a lot of scenarios right now."
Stocco and Rao's system works by capturing the brain waves—electrical activity in the brain's neurons—of one subject, called the "sender," via EEG. These signals are associated with an action. In the case of Stocco and Rao's tests, this action was tapping out a keyboard command in a simple video game.
The sender's brain wave signals are then digitally processed and sent over the internet and into the motor cortex of the "receiver" by way of transcranial magnetic stimulation, or TMS. TMS non-invasively stimulates the right population of neurons in the receiver's brain, effectively making them act out the command that the sender's brain communicated.
Their system allows one person to effectively control someone else's actions by communicating directly with their brain.
The communication between brains doesn't have to be instant, as researchers demonstrated earlier this year by emailing encoded brain waves. Storing encoded EEG signals as a kind of action "template" and communicating them into the brain of someone re-learning basic motor skills after suffered brain damage from a stroke, for example, could speed up the rehabilitation process.
This method would be similar to current approaches to neurorehabilitation for congenital blindness, which electrically stimulates neurons along the visual pathway in an effort to kickstart vision.
"The way you learn is by trial and error," Stocco explained. "Your brain tries to do some kind of motor activity, you observe the result and know whether it was successful or not, and the error signal is used by the brain to essentially alter the plasticity of the remaining tissue in the right direction. In real life, that's the only signal you have."
"But we could speed up this process if we could give, instead of a single scenario that you're doing right or wrong, a more precise signal like this part of the movement is wrong," he continued. "This is equivalent to transmitting a template to the part of the brain that handles what is the intention, what is the right movement to perform."
A potential hangup for this approach, Stocco said, is that the relationship between brain waves and specific actions in the context of neurorehabilitation is likely highly specific to individuals. Thus, a plausible future scenario for their technology could involve someone encoding various brain wave-action templates for future use. In the event of a stroke or some other event that causes brain damage, their specialized templates could be loaded directly back into their brain for quicker neural retraining.
The ability to test the associations between neural signals and specific actions could also be used to test theories in neuroscience more generally. A huge issue with current research into associating thoughts or actions with specific populations of neurons is that it's all about correlation, not causation.
Activity in the brain is easily monitored with fMRI scanning and other methods, but its association with certain actions is usually established through self-reporting or other indirect methods. Take, for example, this recent study, which associated neuron populations in the ventral striatum with choking under pressure by analyzing subjects' performance in a game.
In other words, while we can often tell where things are happening in the brain, we don't necessarily know what is happening, and our methods of confirming associations are often oblique. According to Stocco, a stable BBI could allow researchers to cover this gap in research.
"A brain-to-brain interface that really works would be able to identify which features are actually useful and necessary and sufficient conditions for a certain thought, and which are just spurious correlations," Stocco said. "A working brain to brain interface is really the ultimate test of neuroscientific theories."
Stocco and Rao's system is currently in the pure research phase, and requires a hell of a lot of additional research and testing to get to the level of accuracy required to be used in these futuristic ways. Among other things, neural stimulation techniques have to move beyond the 40 year old standard of TMS in order to target smaller populations of neurons, Stocco said.
Even so, brain-to-brain communication tech, like many other research projects aimed firmly at the future, is progressing slowly but surely. Even though it doesn't look like we'll be telepathically communicating with personal BBIs any time soon, Stocco and Rao's research could prove to be a jumping off point for any number of crazy advances in the field of neuroscience.