06 Oct

If I refer to the Larousse dictionary, it is telepathy which I will talk about today. That is to say, the transmission of any thoughts or impressions of a person to another without any communication with known sensory pathways. Science fiction you say? Yet it’s just the Science! And hop 2 steps from Science!

The Washington University researchers conducted the first experiment that directly connects two human brains, allowing a participant to guess what the other is thinking. The interface between the two brains is noninvasive, that is to say, the instruments are not in direct contact with the skin, which is a real achievement. This interface requires an electroencephalograph which detects specific patterns of brain activity of a participant (called “interviewed”), while the second participant (“investigator”) receives information using transcranial magnetic stimulation. Imagine that these two people are playing the game “Who is it? “. In one room, one asks several questions and manages to guess the object to which the other thinks several meters away in a second room.

“This is the most complex brain-to-brain experiment, I think, that’s been done to date in humans,” said lead author Andrea Stocco, an assistant professor of psychology and a researcher at UW’s Institute for Learning & Brain Sciences.

The study builds on previous work dating from 2013. While some researchers connect the brains of rats or monkeys using electrodes inserted into the brains of animals, the team of Andrea Stocco was the first to use a non-invasive technology (as a nice little shower cap).

Their new work represents an innovation noninvasive brain-brain connection because they use:
– Stimulation of the visual cortex of the “questioned” to transmit visual stimuli that are perceived by the “investigator”
– Brain-brain connection in real time via the internet, rather than off-line communication
– An interactive problem in which “the investigator” and “interrogated” must exchange two-way information to solve the problem together.

The results demonstrate that by using their system, 10 people (5 pairs interviewer / interviewed) can successfully identify the “mystery object” to discover using a question-response protocol (true / false) similar to the game “Who is, what? “. Indeed, a participant looks at an image on a screen (for example, a picture of a car or an apple) and has to guess the object to another player.

To understand the principle of their system, let me return to the notion of brain waves.

Brain waves

            The human brain is composed of different areas, the visual cortex, the emotional area, the area of ​​language, etc … The nerve impulse works rhythmically and coordinated, that is to say that neurons are activated by pulsation gradually, then return to a resting state and then activate it again. Through small electrodes connected to an electroencephalograph, the pace of these pulsations may result in waves (or neural depolarization). The intensity of brain activity is shown by the frequency of these waves. They are calculated in hertz (Hz). If the graph recorded by the electroencephalograph is flat, it means that there is no brain activity. In addition, the brain wave frequency varies with the type of activities in which we are engaged. In the specific case of the system devised by researchers at the University of Washington, the electroencephalograph of “interrogated” saves a different signal depending on whether the person watch a glittering LED 13 or 12 Hz.

The procedure for the “interrogated”

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Participants playing the role of “interviewed” were equipped with an electroencephalograph cap and sit in front of a screen (Figure 1A) displayed with “yes” and “no” at the bottom corners. Two flashing LEDs are placed on both sides of the screen; LED “Yes” (Figure 1B) flickers to 13 Hz, while LED “No” (Figure 1C) flickers to 12 Hz. During the session, the electrical signals from the cerebral cortex of the participant were recorded. According to the profile of the electroencephalogram, the signal is translated into “yes” or “no” to “investigator”.

The procedure for the “investigator”

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“The investigator” before his eyes a list of several objects which allowed the other participant chose one. To find the solution, he asks questions to “interrogated” by a computer and an internet connection. Magnetic stimulation is sent to the occipital cortex of the investigator if the answer is “yes” via a transcranial magnetic stimulation (Figure 2BC) causing the perception of a phosphene. If he answers “no”, no signal is transmitted. A phosphene results in the sensation of seeing a flash of light, spots or lines in specific areas of the visual field, including eyes closed. Depending on the signal that the investigator receives or not, so it can guess the answer to his question. After several rounds, so it is able to know which object the other participant thought.

Without real application for the moment, these works represent a particularly beautiful proof of concept.

Sources :
Playing 20 Questions with the Mind: Collaborative Problem Solving by Humans Using a Brain-to-Brain Interface, Andrea Stocco et al., 2015, PLOS One
A Brain-to-Brain Interface for Real-Time Sharing of Sensorimotor Information, Miguel Pais-Vieira et al., 2013, Scientific Reports


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