This article is taken from the monthly Sciences et Avenir – La Recherche n°910, dated December 2022.
Neurotechnologies are not limited to repairing the brain, they could even improve it! This is one of the fantasies of the transhumanist movement, which envisages the advent of a human being biologically augmented by technology. A fantasy that could soon become reality thanks to – or because of – billionaire Elon Musk and his company Neuralink.
The stated objective of the start-up founded in 2016 is to connect the human brain to devices such as computers or mobile phones. For this, an implant would be installed in the cerebral cortex, sending and receiving information between our neurons and the machines. A brain-machine interface (BCI) that Elon Musk would like to couple with artificial intelligence to increase our cognitive abilities tenfold. To succeed in his bet, the founder of SpaceX and Tesla has bet everything on technology, designing much more advanced implants than those created by his competitors.
The chip, tested on pigs in 2020 then monkeys in 2021, measures 23 mm wide and 8 mm thick and is recharged by induction, wirelessly. Inserted into the brain by a surgical robot using a technique similar to that of a sewing machine, it is made up of 1024 fibers carrying electrodes. These advances should make its installation safer and thus avoid the risks associated with this type of brain device. But the Neuralink implant has never been tested in humans, and experiments carried out in primates – including one capable of mastering the Pong video game “by thought” – show that the technique is not perfect, at least point that the company is currently being sued for animal abuse.
But there is not necessarily a need to have an implant in the brain to communicate with the machines. Other less invasive approaches are already being used to convert brain activity into digital commands. The most widely used technique is the electroencephalogram (EEG), which captures brain activity through electrodes placed on the scalp. These signals are then transferred to a receiver which transforms them into an electrical signal that can be read by a computer, itself connected to a machine. Thus, the system could for example detect if a person wakes up and send the information to his coffee machine so that an espresso awaits him in the kitchen after his shower!
“In the near future, these systems will be accessible to everyone, such as smartphones today, predicts Aleksandra Kawala-Sterniuk, a researcher specializing in brain-computer interfaces at Opole University of Technology, Poland. They will be easy to wear, integrated into clothing, for example. And they will become the equivalent of voice command assistants like Siri: everything that we can currently control with our voice can be controlled by our thoughts thanks to these interfaces, in particular entertainment applications. “
Add new senses or new features
Technology would thus make it possible to add new functionalities to the brain, as today we add applications to our smartphones. There are even some who have already managed to add new senses! This is the case of the British artist Neil Harbisson, inventor of an antenna that transforms colors into sound frequencies, making the bones of his skull vibrate until he stimulates his inner ear, which allows him to hear color!
“It’s not an improvement or an increase of something we already have, but the addition of a new sense, something that no one else had. A new way of perceiving reality, because that’s the purpose of art, to show us another vision of the world “, explains this artist who uses this new meaning for his works of art. With an additional advantage: unlike biological organs, artificial ones can be continuously improved. Neil Harbisson’s antenna is a good example. When he created it in 2004, it perceived 25 colors.Today, it restores the 360 colors visible to the human eye, but also ultraviolet and infrared!
Another possibility is to increase the capacities of the brain by stimulating specific areas, in particular to increase attention, memory, alertness, and even reasoning skills. A whole field has even emerged for this purpose: neuro-ergonomics. This consists of monitoring brain activity by electroencephalography and, if a drop is observed, for example when the person begins to tire, a specific area of the brain is stimulated to enhance activity in this area.
antenna developed by artist Neil Harbisson allows him to hear colors by transforming them into sound frequencies. Credit: MATTHIEU GAFSOU/MAPS
Approaches that still lack precision
The most studied technology for this is transcranial magnetic stimulation (TMS), which uses a magnetic field to transmit an electric current to a specific area of the cerebral cortex. Unlike the electric shocks of yesteryear, these currents are not painful and manage to trigger nerve impulses in the neurons of the targeted area. “This technique has been successfully tested with air traffic controllers to improve their attention, reveals Caterina Cinel, researcher in neuroscience and neural engineering at the University of Essex, UK. But the TMS is not very precise: the stimulated zone being too wide, it is impossible to know when one stimulates and when one inhibits the neuronal activity. In short, we do not really know how it works or how long it manages to stimulate the brain. “Other more precise approaches exist, such as transcranial direct current stimulation, which is also more practical to use (the device being less bulky than that for transcranial magnetic stimulation).
“You can even find these devices on Amazon! But their use outside laboratories is strongly discouraged, because we do not know the consequences on the brain of regular stimulation, alert Caterina Cinel. Nevertheless, it is a more likely technology in the near future than TMS. “
The most precise still would be to stimulate the brain directly from the inside, as is done to treat the tremors of Parkinson’s disease or to prevent seizures in severe epileptics. Thus, researchers can sometimes take advantage of these devices already in place to test the stimulation of very specific areas of the brain, in particular to improve memory. “But it’s a far too invasive approach, which is also complex, because the stimulation this time is too precise: once installed, the implant will only stimulate the region where it is located, so you have to know exactly where to place it, she adds. Non-invasive techniques are much more flexible in this regard. “
For the moment, these non-invasive brain stimulation technologies are experimental, but many experts see them becoming a reality in the coming decades. “We don’t master these technologies yet, they are not precise enough, so we don’t control what is stimulated, notes Caterina Cinel. Also, our attention and our cerebral resources being limited, there is a risk that the stimulation of a cognitive function decreases the efficiency of other functions at the same time. For example, that an activity like speaking becomes more difficult if our attention is increased and focused on another activity. But I think twenty years from now we could use these stimulations in everyday life: if we feel tired, but we know we still have a lot of work to do, a little brain stimulation could help us.” The race for performance is on, but we will need less coffee.
The limits of brain implants
Reading or stimulating the brain is much easier if the electrodes are closer to it. The further away you go, the fuzzier the signal of brain activity becomes. This is why the American start-up Neuralink is betting everything on its brain implants, installed in direct contact with the cortex. But these devices implanted in the brain are not yet viable.
First, their installation involves open-brain surgery, with the risk of infection, haemorrhage, not to mention possible involuntary damage to this vital organ. Significant risks that could be justified to treat a serious illness, but which are difficult to envisage in someone in good health. In addition, these devices would need to be replaced regularly, as they have an actual lifespan of approximately one year. Over time, there is an accumulation of fibrous tissue around the electrodes, caused by the mismatch between the stiffness of the electrode and the flexibility of the brain tissue, which leads to constant friction, and therefore chronic inflammation. The sensitivity of the device thus drops quite quickly.
But a new approach could make these brain implants viable. In 2021, Australian researchers invented a method to implant the electrodes by passing through the blood vessels of the brain (see diagram below). They are therefore placed in a specific location, but without being in direct contact with the brain tissue, avoiding inflammation problems.
This implant avoids having to resort to surgery with open brain since it is introduced under the skull by a vein of the neck. Credit: BRUNO BOURGEOIS
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Brain-machine interfaces: increased cerebral capacities – Sciences et Avenir
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