Neuralink, la société d’Elon Musk qui développe un nouveau type d’implant cérébral, a commencé sa recherche de personnes handicapées pour des tests sur les humains. Cet appel à volontaires intervient, alors que Neuralink est accusé d’avoir fait preuve de cruauté envers des singes utilisés comme cobayes.
Cherche patients tétraplégiques volontaires pour tester pendant six ans un implant cérébral imaginé et promu par un milliardaire extravagant et controversé. La société américaine Neuralink, fondée par Elon Musk, a lancé mardi 19 septembre son appel à participer aux premiers essais cliniques sur des humains de son implant cérébral. Une technologie décrite tour à tour par son inventeur comme capable de rendre une certaine mobilité aux personnes paralysées, de permettre de jouer à des jeux vidéo par la pensée ou encore d’apprendre les langues en dormant.
However, for now, the upcoming trials will be limited to potential therapeutic benefits for individuals suffering from severe neurological injuries. Neuralink hopes to find nine tetraplegic candidates willing to receive an implant that is « clearly invasive and will be inserted into the motor cortex of the brain [to control body movements], » as summarized by Adrien Rapeaux, a researcher at the Next-Generation Neural Interfaces Laboratory at Imperial College. The promise, in addition to compensation for « trial-related costs, » is that Neuralink will allow them to « control external devices through thought, » such as leg or arm prosthetics.
Des fils plus fins qu’un cheveu
« I cannot reword »
In reality, there are other deep brain implants that have been tested on humans, but they are quite rare, and the envisioned Neuralink device is new, according to Christian Claes, director of ClaesLab. It is the first implant made up of independent ultra-thin wires, to which the electrodes intended to be inserted into the skull are attached in order to capture neuronal signals. The main alternative to invasive implants comes in the form of a small electrode mat.
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The Neuralink solution offers the « dual advantage of being flexible and wireless, » summarizes Art Pilacinski. Its non-rigidity allows the person to move while minimizing the risk of the implant causing damage to the brain. This is one of the main reasons why, along with other implants, patients are advised not to move.
The fact that the Neuralink device operates wirelessly is intended to « make it invisible, » according to the American company. « In this case, there is no wire connecting the implant to the machine that is supposed to analyze and decode the signals captured in the brain, » explains Christian Claes. This is both an aesthetic advantage and one that is meant to facilitate the mobility of the person wearing the implant.
Les volontaires pour les tests cliniques s’avanceront donc en terrain scientifique relativement inconnu. Et dans le cas d’une procédure nécessitant une intervention chirurgicale telle que l’ouverture de la boîte crânienne pour y insérer un dispositif qui n’avait encore jamais trouvé sa place dans un corps humain, ce n’est pas anodin.
« I cannot reword »
Risque d’infection et réaction immunitaire
Adrien Rapeaux believes that these tests aim to restore mobility to severely paralyzed individuals because there are no other procedures available to achieve this. The FDA (Food and Drug Administration, responsible for approving the marketing of drugs) would likely not have approved if Neurolink had proposed testing such an invasive procedure on healthy patients to see if it allowed them to play video games using their thoughts.
The main risk of this procedure lies in the possibility of post-operative infection, as explained by all the scientists interviewed by France 24. In the brain region, the consequences could be catastrophic.
D’où l’intérêt du recours prévu à un robot, développé spécifiquement par Neuralink pour procéder à l’opération. “Il est beaucoup plus aisé de stériliser un robot qu’un humain ce qui réduit le risque d’infection”, souligne Art Pilacinski.
The robot has another advantage: its precision work can reduce the risk of triggering a strong immune response. This is a known issue with implants: « The immune system sees them as foreign bodies and, since it cannot destroy them, it isolates them by surrounding them with a layer of dense tissue, » explains Adrien Rapeaux. By being isolated in this way, the implant will have much more difficulty capturing signals from neurons and, ultimately, would become useless.
To minimize the immune response, one must, for example, avoid bleeding. « It’s impossible for a human surgeon, but a highly precise robot can hope to navigate its way between blood vessels, » explains Adrien Rapeaux.
Le dispositif de Neuralink présente aussi un risque très spécifique lié à son fonctionnement sans fil. Il faut pourtant qu’il soit alimenté par une source d’énergie pour fonctionner – comme par exemple une petite batterie interne – et “cela entraîne un risque de surchauffe qui peut procurer une sensation d’inconfort plus ou moins forte”, note Art Pilacinski.
Singes morts
Finally, these tests will assess the true quality of communication between the human brain and the Neuralink device. So far, « Elon Musk has only demonstrated that a monkey equipped with the implant could play Pong with its brain, which is not really groundbreaking, » notes Adrien Rapeaux.
Most of the tests have already been conducted on macaques. And this is not necessarily reassuring for potential volunteers. Neuralink has been the subject of three investigations in the United States to determine if the experiments were not particularly cruel to these subjects, according to the interviewed scientists.
A letter from the committee of scientists for « responsible medicine » was also sent on September 20th to the authorities, requesting the opening of an additional investigation, providing detailed information about the suffering inflicted on monkeys, which in several cases led the laboratory workers to euthanize the animals.
Il est ainsi question “d’infections chroniques”, d’”œdèmes cérébraux”, ou encore “de bouts d’implants égarés dans le cerveau”. La lettre décrit des animaux cherchant à enlever les implants, d’autres pris de spasmes et, pour certains perdant l’équilibre après avoir été opérés pour l’insertion de l’implant.
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