The science of tomorrow: Brain-connected implants restore sensation to paralyzed patients

© Ashutosh Sonwani/Pexels

Brain-machine interfaces (BMIs) are really starting to work wonders. Theoretically imagined by Jacques Vidal in 1973, this idea, long considered utopian, is now becoming a tangible reality. Neuralink is certainly the leading example of next-generation BMIs, with the N1 chip at the heart of the system, capable of capturing and decoding neural signals in real time. Last year, a first patient was implanted (Noland Arbaugh, delighted with this experiment), then a second, a few months later, for whom the implant was also a success.

However, Neuralink is far from being the only company investing in this field. In a Swedish laboratory, Two patients take part in an extraordinary experiment. Deprived of mobility following spinal cord injuries, they are now able to perceive shapes, curves and textures thanks to an ICM device.

Artificial touch: a new language for the brain

Professor Giacomo Valle's team, attached to the Department of Technology at Chalmers University in Sweden, has developed a novel method for translating tactile information into interpretable brain signals. This is thanks to a system of electrodes implanted in the sensory and motor regions of the brain, specifically those dedicated to hand and arm movements.

The complexity of this approach lies in the need to encode precise neurological messages. “We had to send a message to the brain that speaks the language of the brain ,” Valle explains. Any imprecision in this neurological dialogue could cause patients to experience confusing sensations. The researchers therefore developed a protocol for recording and decoding electrical activity patterns associated with hand movements.

The particularity of this approach lies in its bidirectionality: beyond the simple reading of brain signals allowing the control of a prosthesis, the system manages to generate artificial tactile sensations perceived as natural by the brain. ” We are reaching a new level in the creation of artificial touch », Valle emphasizes, « this sensory richness seems essential to us to reach the level of dexterity and manipulation characteristic of the human hand ».

A paralyzed patient explores his new sensations through a bionic arm connected to the ICM. © Charles M. Greenspon/University of Chicago

A progressive reconstruction of sensations

The experiment was carried out according to a progressive protocol, allowing patients to rediscover step by step the world of tactile sensations. The experimental sessions first began with the sending of elementary stimulations, allowing patients to perceive sensations as simple as touching the edge of a table.

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Given the encouraging results of this first phase, the researchers made the spectrum of stimulation more complex. The device transmitted more sophisticated information, giving patients the ability to recognize complex geometric shapes and characters with rounded contours.

The culmination of these experiments was reached when the participants were able to feel objects in three dimensions and perceive the movement of stimuli over the entire surface of the bionic hand, including the fingers. A proof of the extraordinary resilience of our brain organ, capable of reinterpreting and assimilating new sources of sensory data.

Valle and his team were particularly impressed by the efficiency of the system, despite the limited number of neurological channels (communication pathways within the nervous system) used for signal transmission. This achievement suggests even greater possibilities with the development of systems with a greater density of neural connections.

One of the patients, in remotely touching a Logitech steering wheel dedicated to car simulation. © Giacomo Valle/University of Chicago

Digital skin: the next challenge for ICMs

Transposing this technology from the laboratory to a Widespread clinical application will still require many technical advances. At the heart of these challenges is the development of a “digital skin”, an interface capable of capturing and instantly transmitting to the brain all the wealth of tactile information. This electronic membrane will have to reproduce the sensory complexity of the human epidermis: pressure, temperature, texture, while ensuring almost instantaneous neuronal communication.

Current research on “E-skin” (electronic skin) and biomimetic prostheses fortunately offers promising avenues. These synthetic tissues, equipped with microscopic sensors, are beginning to match certain properties of human skin. Companies specializing in ICMs, such as Neuralink and Synchron, are helping to accelerate these developments thanks to their colossal investments; means that research laboratories do not necessarily have.

The patients currently being tested in Sweden are the actors in an exceptional scientific adventure, devoting up to three hours per session to recording and analyzing sensory data. All this while being aware that this work may not benefit them directly. “Without their contribution, none of this would be possible,” Valle emphasizes. These pioneers, by agreeing to explore the frontiers of artificial perception, are participating in crossing a new (long) stage in the history of regenerative medicine, without expecting anything in return: true heroes of science !

• Swedish researchers have developed a technology connecting the brain to a bionic arm, allowing paralyzed patients to regain tactile sensations.
• The bidirectional system translates signals between the brain and the prosthesis, accurately reproducing sensations such as touching objects or perceiving complex shapes
• While promising, the technology will still require much progress, particularly in the development of “digital skins” to one day consider broader clinical applications.

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