We already have brain-computer interface systems that allow people to control cursors on a screen using the power of thought. But what about sharing thoughts between two minds? A group of neuroscientists at Harvard have found a way to do it — with a human and a rat.


Neuroscientist Seung-Schik Yoo and colleagues wanted to show that a computer could actually send information from one brain to another. And they wanted to do it non-invasively, without sticking electrodes into anybody's brain. Plus, they wanted to go beyond a previous experiment where one rat sent brain signals to another rat. So they developed a device that would read signals from a human brain, and feed those signals to a rat's brain. In the end, their human subjects were able to make a rat move its tail just by thinking about it.


Here's how they did it.

First, they put an EEG device on a human. EEG measures the brain's electrical signals through the skull. To boost that signal strength, they had the humans look at computer monitor that was flickering at a very specific frequency. Every time the humans looked at the flickering monitor, that frequency was sent to the EEG monitor. So when the humans wanted to signal "move your tail" to the rat, they would look at the monitor and their brains would send the signal.

To control the rat, Yoo and his colleagues used focused ultrasound (FUS), which can harmlessly beam an ultrasound signal into a specific spot in the brain, exciting the neurons around it. So the rat, who was under anesthesia at the time, had its head under a FUS beam, which excited its motor cortex and caused it to twitch its tail while it slept.


The setup worked nicely. In a paper published earlier this year in PLoS One, the researchers report that the humans looked at the flickering monitor, the EEG picked up the signal, and then a computer translated it into a command sent to the rat's brain via FUS.

Obviously this was a fairly simple experiment. The human couldn't send compex commands to the rat, like "stand up, walk left, and open the treasure chest." More importantly, communication was one-way. The rat couldn't send signals to the human. But the proof of concept now exists, and the researchers believe it could lead to human-to-human brain interfaces.


They offer one example of how such a brain-to-brain interface might work. It's known that people sometimes experience "neural coupling," where "the neural processes of one brain are coupled to the neural processes of another brain through various environmental routes, including indirect sensory/somatomotor communication." Experiments have shown that when people understand each other while talking, they exhibit similar patterns of activation in their brains. Yoo and colleagues wonder if their system might "augment this mutual coupling of the brains," and "have a positive impact on human social behavior." In other words, you might put on a device like this during couples counseling so that you can sympathize more with your spouse during arguments.

Using this device might also help you train your dog. Or, you know, it might be something you'll be forced to wear when your boss or political leader wants you to sympathize with their agendas.


Yoo and his colleagues are well-aware of this possible dystopian application of their brain-to-brain interface, and admit as much in the final paragraph of their paper:

It is reasonable to assume that further advancements and establishment of BBI between human subjects, as well as within or across species, have the potential to trigger breaking ethical questions that cannot be satisfied by applying contemporary ethical concepts. However, it is beyond the scope of this paper to address the particular moral and philosophical issues and complex challenges, possibly even undesirable consequences that may arise with the future application of this emerging technology.


What they are saying here is that we may not even have the ethical concepts to encompass the possible uses of this technology, which sounds like something out of Ramez Naam's novel Nexus. It also sounds incredibly disturbing. Are we opening the door to new vistas in human cruelty, or new avenues of communication between species? Hopefully our ethical development will outpace the development of this technology.

Read the full scientific paper in PLoS One