Neuralink: what is Elon Musk's brain implant received by a first human being?

“The first human received a Neuralink implant yesterday, and is recovering well. Initial results show promising detection of neuronal activity. True to form, it was on in a human brain.

As always with Elon Musk, things move quickly. In May 2023, the FDA (the American regulatory authority) granted Neuralink authorization to conduct its clinical trial, which it had refused the previous year for reasons of device safety, without us knowing this. which motivated his change of mind. Last September, the company announced (still on . For this first study, Neuralink was looking for patients suffering from “quadriplegia due to cervical spinal cord injury or amyotrophic lateral sclerosis (ALS or Charcot disease, Editor’s note)”.

Concretely, it involves implanting within the brain, in the regions which control movement, flexible wires covered with electrodes responsible for detecting the "action potentials" triggered by the neurons, and carrying the " intention” of the implant wearer. These brain signals are transmitted wirelessly to an external device, which decodes them.

In March 2021, Musk and the Neuralink teams described in detail their implant and the surgical robot specially developed to install it in the journal Cureus. The implant, the size of a small coin, is made up of a set of 96 flexible and thin probes, made of polyamide covered with a thin layer of gold. This allows, the authors believe, to improve biocompatibility compared to rigid metal wires, and to allow them to move according to brain movements.

Each wire has electrodes and a sensor to communicate with the chip and amplify the signal. The wires measure 4 to 6 micrometers in diameter (less than a red blood cell) and 20mm long, and end with a loop “to facilitate insertion”. To record and transcribe in real time the signals picked up by the electrodes while extracting from the ambient “noise”, 256 individually programmable amplifiers, on-chip digital converters, and a peripheral control circuit are also present.

Unlike the human hand, the robot is, the authors explain, “capable of individually inserting each wire with great precision and safety, while avoiding surface vascularization and targeting specific brain areas.” Tested on 19 rats at the time, it showed a success rate of 87.1%.

Two variants have been developed by the Neuralink teams. The first has 1535 electrodes, of which 1344 can be recorded simultaneously. The second has 3072 electrodes (32 per wire) and can simultaneously record the signals perceived by all of them. An impressive step, when the implants developed by academic research manage to record at most 200 to 300 electrodes simultaneously!

But what will this implant be used for? This is one of the many questions that remain to be resolved. “Neuralink’s first product is called Telepathy. It allows you to control your phone or your computer, and through them almost any device, simply by thinking,” launched Elon Musk last night on the implant has already tested it.

The objectives of this first clinical study, called “Prime” (for Precise Robotically Implanted Brain-Computer Interface), are in any case modest: it involves evaluating “the safety of our implant and our surgical robot”, as well as “the initial functionality of our implant to allow paralyzed people to control external devices through thought,” Neuralink announced in September. In practice, implanted people will be asked to perform tasks as simple as the video game “Pong”, which consists of moving one or more cursors to make a ball bounce on a computer screen.

After that? The intentions displayed by Elon Musk are as great as they are varied: activating robotic arms or exoskeletons, allowing paralyzed people to regain control of their limbs, detecting the recurrence of a brain tumor as early as possible, allowing people suffering of locked-in syndrome to express oneself and control machines, restore sight to the blind, treat Alzheimer's or Parkinson's... and of course, lead to "augmented man" by directly connecting his brain to artificial intelligence .

Without even mentioning the ethical problems linked to this latter use, many steps will remain to be taken. First, what could be the point of implanting 3000 electrodes, rather than ten times fewer? Elon Musk has undoubtedly improved the brain implant; It remains to be seen what to do with this improvement...

Implants to treat Parkinson's using deep brain stimulation have existed for many years, but nothing says that increasing the number of electrodes would improve the effectiveness of the treatment. To restore mobility to paralyzed patients, it will be necessary to cross the barrier of the spinal cord: allowing the brain to control the movement is not enough, this intention must also be transmitted to the muscles via the spinal cord.

To do this, several teams around the world have already developed implants capable of delivering electrical impulses to control muscles. Thus in Switzerland, a team led by Grégoire Courtine, neuroscientist at the Federal Polytechnic School of Lausanne (EPFL), and Jocelyne Bloch, neurosurgeon at the Vaud University Hospital Center (CHUV), designed a palette of electrodes implanted on the spinal cord of paraplegic patients. The latter allowed them to walk again, first via a computer program controlling the impulses in 2018 then 2022, then directly by the patient via a brain implant developed by CEA researchers, at the Clinatec laboratory in Grenoble.

Will the implant developed by Elon Musk allow us to take a step forward in the care of these patients? From SpaceX to Tesla, the American billionaire has accustomed us to crazy projects that succeed. And for him, the line between useful revolution and cataclysm is probably as fine as the electrode wires inserted into this first patient...