A meeting of the minds

By Lauren Davis
Thursday, 13 November, 2014


The idea of telepathy - ie, the ability for two people to communicate using nothing but their minds - is a common notion in science fiction but not so believable in the real world. Yet while such a direct link is yet to be established, an international research collaboration has built a pathway that makes brain-to-brain communication possible - with a little help from the internet.

The team comprised researchers from Spain, France and the USA and was led by Giulio Ruffini, the CEO of Starlab Barcelona. Writing in the journal PLOS ONE, the scientists expressed their belief that we are entering a new era in which the minds or brains of different individuals will be able to communicate. They noted the development of brain-computer interfaces (BCIs) and computer-brain interfaces (CBIs), the latter enabled by non-invasive brain stimulation techniques.

The combination of these two technologies, according to the researchers, can be combined to realise “non-invasive, computer-mediated brain-to-brain (B2B) communication between subjects”. In light of this, the team recruited four healthy study participants: one ‘emitter’ assigned to the BCI branch of the experiment in India and three ‘receivers’ to the CBI branch in France. The aim of the experiment was to successfully transmit a message from the emitter to the receivers using the internet as a pathway.

The message was encoded as a series of 0s and 1s, represented to the emitter as target cues on a screen (in the downright part of the screen for bit value 0 and the upright part for bit value 1). The emitter utilised electroencephalography (EEG) through motor imagery - if the bit in question was a 1, the emitter was to think about moving their hands (for 0, their feet). These thoughts controlled a ball on the screen that moved towards the target. If the ball hit the target, the bit was correctly encoded. The result was sent via email to the CBI subsystem.

On the other end of the experiment, the CBI subjects received pulses of transcranial magnetic stimulation (TMS) to the brain, delivered by a robotised TMS system, which would induce the perception of light flashes called phosphenes. The researchers identified a TMS phosphene-producing hotspot in the right visual occipital cortex, which was used for the active condition (to encode the bit value ‘1’). The intensity of pulses was adjusted for each subject, as was the occipital cortex site targeted for the silent condition (0). Various measures were employed to ensure subjects were not receiving tactile, visual or auditory cues from the positioning of the TMS coil.

View of emitter and receiver subjects with non-invasive devices supporting, respectively, the BCI based on EEG changes driven by motor imagery (left) and the CBI based on the reception of phosphenes elicited by a neuronavigated TMS (right). The successfully transmitted code in the particular scenario shown is a ‘0’: the target and ball are at the bottom of the screen and the TMS coil is in the orientation not producing phosphenes. doi:10.1371/journal.pone.0105225.g002

The first message - “hola” - was encoded and delivered to France via email on 28 March 2014. It was delivered as TMS pulses to receiver subject 3, who reported verbally when they saw a phosphene. The same method was employed for a second message - “ciao” - on 7 April, this time to receiver subject 2. The words were encoded using a 5-bit Bacon cipher and replicated for redundancy seven times, totalling 140 bits. The resulting bit streams were randomised using cyphers selected to produce balanced pseudo-random sequences of 0s and 1s.

The researchers boasted impressive results, stating, “In the first experiment the transmission error rates were of 6%, 5% and 11% for the BCI, CBI and the combined B2B components respectively, and in the second, error rates were of 2%, 1% and 4% respectively. We note that the probability of transmission of lists of 140 items having occurred with the low observed error rates or less by chance is negligible.”

But there has been some dispute surrounding the originality of the study, with the revelation of a similar experiment conducted by the University of Washington (UW) in August 2013. The pilot study, which was published on a website as opposed to in a journal, was titled ‘Direct Brain-to-Brain Communication in Humans’ and chronicles the use of EEG for recording brain signals from a ‘sender’ and TMS for stimulating the brain of a ‘receiver’.

In the UW study, subjects were tasked with playing a computer game where they must fire cannons to destroy rockets heading towards a city. The sender could see what was happening on the screen but could not actually press the ‘fire’ key (the space bar on a keyboard). As the sender imagined moving their right hand, the signal was translated by the computer to a magnetic stimulation pulse that was delivered to the left motor cortex region of the receiver. The stimulation causes a quick upward jerk of the receiver’s own right hand, which was resting slightly above the space bar and typically resulted in the key being pressed.

It is the involuntary nature of the UW receiver’s movement which differentiates this study from Ruffini’s the most, the action being subconscious as opposed to conscious. The authors of the most recent study noted three features which make their work stand apart from others: “a) the use of human emitter and receiver subjects, b) the use of fully non-invasive technology and c) the conscious nature of the communicated content” (emphasis added). The researchers acknowledge previous experiments in the B2B field but conclude that theirs provides “the first demonstration of non-invasive direct communication between human minds”, stressing the conscious activity of the subjects involved.

Even without the controversy, Ruffini’s study has not been without its critics. Many have noted the impracticality of the technique, with the experiment achieving B2B transmission at a rate of 2 bits per minute - meaning each word took 70 minutes to be fully received. This slow speed, combined with the somewhat cumbersome equipment involved, means the system will not be replacing text messaging or email as a handy form of communication any time soon. But it’s a start.

“We believe these experiments represent an important first step in exploring the feasibility of complementing or bypassing traditional language-based or other motor/PNS-mediated means in interpersonal communication,” the researchers said. They suggest that future work in the field could support dialogue between two or more brains or even within the same brain - ie, using information from one part of the brain to regulate phenomena (such as emotions and pain) in another.

“Our results provide a critical proof-of-principle demonstration for the development of conscious B2B communication technologies,” the authors concluded. “More fully developed, related implementations will open new research venues in cognitive, social and clinical neuroscience and the scientific study of consciousness.”

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