Memories are one of the most amazing, amazing and, at the same time, little studied results of the work of the neurophysiological mechanisms of our body. After all, somehow the combination of the work of tiny synapses in our brain and the activation of neurons using them allows images of those things that we remember to appear in our head. The sum of all our memories makes us who we are. They are us in all respects. Without them, we would cease to be who we are.
In one of the episodes of the British science fiction series "Black Mirror" (who has not watched, I highly recommend it), which tells about our possible dystopian future, it was said about a tiny device that is implanted behind a person's ear and gives him the ability not only to quickly recall some a moment from the past, but also “play” this moment in your head in amazingly clear details, like a movie on the screen before your eyes.
Theodore Berger, a biomedical engineer at the University of Southern California, does not promise this level of reversion to memories (which is perhaps for the best), but has been working on similar memory implants for a long time. The device, implanted directly into the brain, thanks to a special method of electrical stimulation of a part of the brain, is able to imitate the functions of the hippocampus, allowing the formation of memories. The tests of the first modifications of such a device were carried out on laboratory mice and monkeys. According to the scientist, it's time to start testing such a device on humans.
Berger's device is based on the theory of how the hippocampus transforms short-term memories (such as where you put your keys) into long-term memory (you can later remember where you put them). The scientist conducted his early experiments on rabbits: first he played a certain sound, and then blew into their faces, forcing them to blink. He soon noted that after the sound was heard, the rabbits would start blinking even without being exposed to the air current. Berger decided to record the activity of the hippocampus at this moment using an encephalogram (he connected electrodes to the rabbit's head that read brain activity) and found that the rabbits learned to associate the sounding sound with the further effect of the air flow on them. The encephalogram picture showedthat the signals in the hippocampus at this moment change in a completely predictable way.
“Through training, the hippocampus has become actively involved in modifying the circuitry of impulses (signals),” comments Gregory Clarke, former Berger student and professor of biomedical engineering at the University of Utah (USA).
Berger himself gave this scheme of applied pulses the name "space-time code". And this code is determined by which neurons in the brain take part in signal transmission and when exactly this transmission occurs.
“The transmission of the space-time code through the different layers of the hippocampus over time turns it into a different space-time code. We don't yet know why, but when it does, the resulting time-space code is what the rest of the brain can perceive as long-term memory,”explains Berger.
The outgoing code is a memory that the rest of the brain uses as a readable and understandable signal. In the case of rabbits, it makes them blink after hearing a certain sound. According to Berger, he was able to derive a mathematical model that, in general, is a rule of behavior for the hippocampus, which is used to convert short-term memories into long-term ones.
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With this general rule in hand, he created an artificial hippocampus for laboratory rats. He first taught rodents to perform memory-oriented tasks. He taught rodents to press one of two adjacent small levers, and then irritated them with a directional light. After a time, when the trained rodent returned to the task, Berger taught him to press another lever, opposite to the one that the rat pressed initially. Thus, it was demonstrated that the rodent remembered what was required of him.
Over the course of these training sessions, Berger and his colleagues recorded the distribution of signals passing through the rodents' hippocampus, and noted that the space-time codes correspond to the memory of the task by pressing the sticks. Scientists have collected information about the signal circuits entering and leaving the hippocampus and, based on this data, developed a mathematical model that could predict the outgoing space-time code corresponding to the originally incoming one. Later, when Berger injected a drug that blocks memory formation in rats trained to push levers, he used his device to electrically stimulate the brain with a pattern of impulses corresponding to the outgoing space-time code predicted by his mathematical model. The experiment ended in complete success. The rats were pressing the right levers.
“Their brains were referring to the correct code as if the code had been created by themselves. This is how we learned to bring memories back to the brain,”comments Berger.
Berger also tested the functionality of the implant in rhesus monkeys, restoring their ability to recall memories from a portion of the prefrontal cortex. This area is involved in the work of executive functions, for example, the use of memories to solve new, previously not encountered tasks. In this context, the implant has also been shown to be effective in improving the memory function of monkeys.
But can a similar implant be used in humans and will it work?
“All of these implants that directly interact with the brain will have to face one fundamental problem,” says Dustin Tyler, professor of engineering at Case Western Reserve University.
“The brain has billions of neurons and trillions of interneuronal connections (synapses) that allow them to work together. Therefore, trying to find a technology that can directly interact with so many neurons and combine them to work at a reasonably high level is extremely difficult."
If cochlear implants that simulate a set of sound frequencies by stimulating the auditory nerve through a couple of dozen electrodes cannot ultimately perfectly imitate sound, then what can we say about such a more complex system like memory. You need to understand that at the current level of methods and technologies, using all these electrodes, scientists are still very far from the real possibility of modeling memories. However, this did not stop a new startup, Kernel, from contacting Berger, hiring him, making him head of its research department and funding his research.
Kernel's initial goal was to bring Berger's implants to the market as medical devices that can help people with various memory problems. Berger is currently conducting clinical trials of his implant on volunteers and reports that patients perform well on memory tests. Ideally, however, according to Kernel CEO Brian Johnson, Kernel wants to develop devices that, through simple and safe surgery, can be implanted into the human brain and enhance human intelligence in areas such as attention, creativity and focus.
Of course, such a result will become a new field of activity for various regulatory authorities and the subject of many disputes and questions: are these devices medical or ordinary consumer? And do we need to regulate their distribution? From the point of view of healthcare organizations, such devices, if, among other things, they are endowed with the ability to diagnose or treat diseases or affect the structure and functioning of the body's functions, most likely will really be considered medical. However, subcutaneous implants capable of enhancing a person's concentration or creativity will likely be able to escape strict regulatory oversight and will be seen as the same regular dietary supplements that stimulate our brain.
Johnson himself did not comment on which direction his company Kernel will work in and what kind of devices it plans to produce in the end. Most likely, everything will depend on the specific individual implant, its functions, scope and potential side effects. Of course, every medical device, like every medicine, has its own side effects. For now, we can only wait and hope that these side effects will have a positive side, and not become another inspiration for the new chilling episode of the series "Black Mirror".
NIKOLAY KHIZHNYAK