In a study that establishes for the first time the feasibility of direct brain-to-brain communication, an international group of researchers has successfully shown it is possible to non-invasively transmit a thought from one person to another 5,000 miles away, without either of them having to speak or write.

In the new article — published in the journal PLOS ONE – the authors argue that what the study shows should probably be termed “mind-to-mind” transmission as opposed to “brain-to-brain,” because “both the origin and the destination of the communication involved the conscious activity of the subjects.”

In the cerebral equivalent of “instant messaging,” the study describes how the international team of neuroscientists and robotics engineers used various neurotechnologies to send messages via the Internet between the intact scalps of two human subjects over 5,000 miles apart – one in India and the other in France.

Electroencephalography (EEG) — which monitors electric currents in the brain — was used to record the information from the sender’s brain, and robotized transcranial magnetic stimulation (TMS) — which causes neurons to fire from an electric current that is generated by a rapidly changing magnetic field — was used to deliver the message to the brains of the receivers in France.

Advancing the brain-computer interface

Researchers have for years been developing noninvasive systems for translating information directly from the human brain to the computer. These systems, called brain-computer interface, often involve brain activity-sensing tools such as electroencephalograms (EEG), functional near-infrared spectroscopy (fNIRS), and functional magnetic resonance imaging (fMRI). Researchers have also, to a lesser extent, experimented with translating information from the computer to the brain, using brain stimulating tools such as transcranial focused ultrasound (FUS), which has been used to link the brains of rats.

Transcranial magnetic stimulation (TMS) is a relatively new method of pain-free stimulation of brain cells. The method, which was presented by Anthony Barker for the first time in 1985, is based on the fact that the cortex — the rind of the brain located directly underneath the skull bone — can be stimulated by means of a magnetic field. TMS is applied in diagnostics, in fundamental research and also as a potential therapeutic instrument.

Used in diagnostics, one single magnetic pulse serves to test the activability of nerve cells in an area of the cortex, in order to assess changes in diseases or after consumption of medications or also following a prior artificial stimulation of the brain. One single magnetic pulse can also serve to test the involvement of a certain area of the cortex in a sensorial, motoric or cognitive task, as it disturbs its natural activity for a short period, i.e. “switches off” the area on a temporary basis. In 2011, researchers described in two studies how they discovered for the first time that the activity of distinct brain cell types changes with different TMS patterns — thus forming the basis for the new research.

The new experiment integrates two of these existing technologies — EEG and robot-assisted and image-guided TMS — to move a message from human brain to computer to human brain. The team behind the study included members from Beth Israel Deaconess Medical Center (BIDMC), a teaching affiliate of Harvard Medical School (HMC) in Boston, MA, Starlab Barcelona in Spain, and Axilum Robotics in Strasbourg, France

Previous studies have already shown that a person can have a conscious thought about moving an arm or a leg, and that thought can be conveyed via EEG-based brain-computer interaction to a computer that passes it to a robot that moves a limb or controls a wheelchair. But this new study takes that two steps further by adding a second human brain to the other end of the communication system, and then separating the sender and receiver by thousands of miles.

The goal, explains co-author Dr. Alvaro Pascual-Leone, was to determine if it is possible for two people to communicate by reading out the brain activity of one person and then injecting that activity into a second person, and to do so while relying on existing communication channels to transmit the information. “[O]ur question was- could we develop an experiment that would bypass the talking or typing part of Internet and establish direct brain-to-brain communication between subjects located far away from each other in India and France?”

Now, the team has shown that the answer to their question is “Yes.”

The researchers recruited four healthy volunteers – aged between 28 and 50 – to take part in a number of experiments. One participant, based in India, was selected as the sender; the other three participants, based in France, were receivers of the messages and had to understand them. The experiment involved a number of steps. Here’s how they did it:

1) Create a binary code for simple words: The researchers encoded the messages “hola” (which means “hello” in Catalan or Spanish) and “ciao” (“hello” or “goodbye” in Italian) into a binary series of “0s” and “1s.” In this particular case, they used a code called a Bacon cipher as their translation guide.

2) Hook the sender up to an EEG: The researchers then connected the sender of the message to a bunch of electrodes in order to read his/her brainwaves using electroencephalography (EEG).

3) Transmit the binary code by having the sender think about their hands and feet: Next, the sender imagined moving his or her feet for 0s and hands for 1s. These are big enough differences in brainwaves that the EEG could pick up the difference. (The researchers used a bit of a cheat at this point: they gave the sender a visual cue: a circle moved on a computer screen in relation to their brainwave output. However, in the future, it’s possible this could be replaced by brain-only feedback mechanisms. Or, with enough training, people might not need feedback at all.)

4) Send the message long distances over the internet: The EEG brain signals were translated into 0s and 1s and then sent via email to the receiving person. In France, a computer-brain interface translated the ‘thoughts’ (codes) into signals that would be directly transmitted to the receiver’s brain using TMS.

The Computer Brain person in India transmitted greetings to people in France, using thoughts alone.

5) Transmit flashes of light to the message-receiver using robotized TMS: The person receiving the message was hooked up to a device that used a magnet outside the head to produce electrical signals within the brain, influencing its activity; this is how TMS works. In this case, the magnet was set up to activate part of the visual cortex — and produce the perception of a flash of light. (This happened even though nothing had actually stimulated the eyes. In fact, the person was blindfolded just to make sure.) It’s a pretty weird phenomenon, called a phosphene.

The flashes appeared in numerical sequences that the receivers could then decode into the messages. The receiver knew that a flash meant “1” and no flash meant “0.” The recipients reported verbally when they experienced a flash; this information was then recorded in binary code (1s and 0s), and then finally translated back into words — “hola” or “ciao.”

Findings are a ‘realization of the first human brain-to-brain interface’

In the first trials, all three receivers translated the messages correctly, the researchers reported. Next, the team carried out similar experiments, transmitting brain signals between Spain and France. The final results showed an error rate of only 15 percent, with 5 percent error rate on the sending side and 11 percent error rate on the receiving side.

The findings show it is possible to transmit a thought (albeit a very basic one) from one person to another without requiring the transmitter to speak or write, the researchers said.”This in itself is a remarkable step in human communication,” says Dr. Pascual-Leone, “but being able to do so across a distance of thousands of miles is a critically important proof-of-principle for the development of brain-to-brain communications.”

The researchers describe their findings as the “realization of the first human brain-to-brain interface.” This is likely the closest that people have ever gotten to telepathy — although, admittedly, it’s still not very close. It’s extremely slow — the equivalent of telepathic Morse code. The total speed of communication using this process was 2 bits per minute, or roughly one millionth the average internet speed in the US. And that meant it took roughly 70 minutes just for one person to say “hola” or “ciao” to another.

Still, the results have major implications for future work in this line of research, confirming that ‘brain-to-brain’ communication can be achieved using TMS aand EEG. “We believe these experiments represent an important first step in exploring the feasibility of complementing or bypassing traditional language-based or motor-based communication,” Dr. Pascual-Leone.

But beyond the scientific implications, future research and advances in the field could potentially lead to major societal changes, says Dr. Pascual-Leone:

There is now the possibility of a new era in which brains will dialogue in a more direct way…



Our results provide a critical proof-of-principle demonstration for the development of conscious [brain-to-brain] communication technologies. More fully developed, related implementations will open new research venues in cognitive, social and clinical neuroscience and the scientific study of consciousness.

We envision that hyperinteraction technologies will eventually have a profound impact on the social structure of our civilization and raise important ethical issues.

It’s worth noting that there’s a dispute over who actually conducted the first demonstration of human brain-to-brain communication. Last year, a group at the University of Washington in Seattle led by Rajesh Rao demonstrated in an unpublished pilot study a very similar experiment involving EEG on the brain-to-computer end of the experiment and TMS on the computer-to-brain end. In that study, the researchers stimulated the motor cortex of the brain, causing the message receiver’s hand to move subconsciously to strike a keyboard. However, the results of that analysis were never published and thus there were no peer-reviewed studies on the topic until now.