"Scientists have solved the mystery of thinking"? So far, unfortunately, not quite yet, but the process is underway. I would like, of course, one day to write a popular science note with such a title, but we are unlikely to live. There was even a temptation to call this article so, in advance - the hand went by itself. But we still held back, because that's not how things are done in neuroscience. Everything happens here gradually. The scientific works of the last month are just a few more steps towards answering the question: "What is consciousness and how does it work?" But for us, naive laymen, it is also better to move towards understanding this secret gradually (otherwise, God forbid, at the most important moment we will not understand anything and we will be upset).
So, today - three steps, three simple facts about the work of your brain.
1. The brain thinks with the body
Here, for example, you took it into your head to read the ancient poet Catullus *. Your eyes run through the lines:
Attis rushed across the seas in a flying, light boat, Hastened with a quick run into the wilderness of the Phrygian forests, In those thickets of dense groves, to the holy places of the goddess.
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We incite with a violent passion that rolled into drunken rage, He castrated his young body with a sharp stone.
At this last phrase, the male reader will probably feel an unpleasant chill in the lower part of the body (“where the vigorous sickle walked,” as another poet, Fyodor Tyutchev, put it on another occasion). See what that means in neuroscience language: While you were reading a phrase, your brain was engaged in recognizing words. In it, in the brain, there are special zones that specialize in understanding the language. However, an unpleasant chill, palpable almost physically at the moment of reading the cherished word, tells us that for some reason completely different areas of the brain were involved in the matter - those that are in charge of processing signals from peripheral parts of the body. Question: did it happen so by chance in the process of perceiving a literary text, or is there some important aspect of the brain?
Even if our reader thinks this is a stupid question, neuroscientists don't think so. Moreover, they have been studying this phenomenon for quite some time. Back in the early 2000s, it was found that when a person hears the verbs "run", "hit" and "kiss" - there is a blood flow to the areas of the brain that control, respectively, legs, arms and lips. In light of the thought experiment with Catullus' text we set out at the beginning of this section, such results do not seem surprising at all. The main question is this: Is this activity of the motor and sensory cortex really necessary to understand what the brain has just heard or read? Perhaps this is just a side effect: first, the parts of the brain that specialize in language understand what is being said, and only then other parts get mildly aroused, although no one asks them to?
In the first task, it was necessary to quickly determine whether the word has any meaning. For example: “draw” - press the right button, “shmakish” - press the left.
An alternative point of view is that this phenomenon is an integral part of understanding the language. It is supported by the fact that the motor areas react to verbs that mean an action very quickly, after only 80 milliseconds, obviously faster than understanding the word. This point of view is gaining popularity, but the final verdict has not yet been pronounced.
It is this hypothesis that neuroscientists from the Higher School of Economics in Moscow, including Yuri Shtyrov and Andrey Myachikov, tried to substantiate. This topic is the subject of their recent scientific work published in the journal Neuropsychologia.
To choose one of the two explanations, you need to do the following: somehow prevent the motor cortex from participating in the work on understanding the text. If understanding deteriorates or slows down, it means that the brain really needs to involve a variety of areas, and not just the notorious language centers in the left hemisphere. If not, then no.
“To interfere with the brain” is nowadays accepted using transcranial magnetic stimulation: a magnetic field pulse temporarily turns off certain parts of the cortex. This is no more harmful than an MRI, and therefore 28 volunteers for the experiments were not difficult to find. It was they who were offered two tasks. In the first one, it was necessary to quickly (by pressing a button) determine whether the word that appeared on the screen had any meaning. For example: “draw” - press the right button, “shmakish” - press the left. The second task is a little more difficult, since it required not only to understand that the word is meaningful, but also to figure out what it means. The subjects had to distinguish concrete actions from abstract ones, for example: "write" - a concrete action, "believe" or "forgive" - abstract.
In the meantime, the subjects were solving problems (or rather, within 200 milliseconds after the word appeared in front of their eyes) - a magnetic impulse rushed through their craniums to the motor cortex, to that part of it that controls the movements of the right hand. You must have noticed that you both "draw" and "write" - actions performed by your hand?
"I know that I know nothing" - this is some idle talk, but Socrates was still a sage
If the reader is interested in experimental subtleties, reservations and corrections, we send him to the article by reference, it is not so difficult, especially if you are a neuroscientist with a diploma. For the rest, we report the result: yes, the effect was indeed observed. That is, the ability to distinguish meaningful words from meaningless words was not affected by a magnetic shock to the motor cortex. But in the choice between abstract and concrete action (when it was necessary to understand the meaning of the word), the difference was obvious: when the motor cortex was inhibited, concrete verbs “draw” and “write” were recognized more slowly, and abstract “you believe” and “forgive” - on the contrary, faster … So, we need the motor cortex not only in order to uselessly wave our hands or draw dumbbells, but also to understand the language.
An attentive reader must have a question. Okay, "you draw" is a simple understandable verb, take a pencil in your hand and draw. But it can also be used in another sense, for example: “In your speech you draw bright perspectives” - no hand is clearly involved here. Or, for example: "You got so drunk yesterday - neither sing nor paint." Do you need a motor cortex to understand such figurative turns of speech?
Not all at once, hurried reader. Scientists from the Higher School of Economics are working on this right now, and the results are going to be reported at a conference in San Francisco in late March. If you believe the published theses of their message (and theses are half a page of text without any details), in "figurative expressions" one should distinguish between metaphor and idiom. For example, "to throw a stone" is a literal meaning. "Quit smoking" is a metaphorical use where instead of "quit" you can use the verb "stop" or "quit". "To cast a shadow" is an idiom: it is impossible to decompose it into separate words and understand them in isolation from each other. It seems that the motor cortex is not needed to understand the metaphor. But idioms in this sense behave exactly like the literal meanings of verbs …
… But shhh. The study authors urged us not to go into the details of this work. We were prompted to mention it only by the fact that not too often a high-quality scientific result is published by scientists from their home country. Shtyrov, Myachikov and their colleagues (although they work not only in Moscow, but also in Danish Aarhus, and in English Newcastle) are exactly the very people to whom the expression "Russian science" can be literally attributed. And since we are celebrating the Day of this very Russian science on February 8, this is an excellent occasion to congratulate our compatriots and talk about their achievements - I hope, without distorting or confusing anything.
And since the next two sections no longer apply to Russian science, we will present them in a much shorter and more concise manner.
2. The brain knows what it does not know
“En eda oti uden eda,” Socrates allegedly said (that is, it is possible that Plato invented it at all, and surely the phrase was misinterpreted by the one who translated it back from Latin into Greek). It seems to me that Socrates did not say that, because “I know that I don’t know anything” is some idle talk, but he was still a sage. Another thing is to know exactly what you know and what you don’t know: this inspires respect. And for this it would be nice to have some kind of register of your own knowledge in your head, keeping it separate from knowledge as such.
Such a register definitely exists in our heads. Proving this is simpler than ever: otherwise there would not have been these torments at the sight of the familiar face of an actor whom you know for sure, but for the life of me don't remember his name and where he was filmed. The brain is sure that this actor is in memory. However, for some reason, it is not immediately possible to find the corresponding entry. There is also the opposite effect, "déjà vu": this is when the brain for some reason thinks that the situation is familiar, but in fact there was nothing like that with it before, but it just seemed.
Neuroscientists talk about it this way: in addition to the memory itself, the brain also has a “meta memory” - this is exactly the memory of what we remember (or should remember) and what not. But what neuroscientists didn’t know until recently was where exactly in the brain this invaluable file cabinet is contained. Japanese researchers have discovered this only now.
There were only two questions to the monkeys: “Have you seen, oh monkey, this picture before? How sure are you that you haven't seen (or seen) her?"
They did their experiments not on humans, but on macaques. The monkeys were offered a series of pictures, and then after a while they were presented with a picture for identification. There were only two questions to them: “Have you seen, oh monkey, this picture before? How sure are you that you haven't seen (or seen) her? Of course, the monkeys were asked not in words, but in the way in which they usually communicate with monkeys: with the right reactions, they received a reward, and for mistakes they had to pay. Meanwhile, the monkey's brain was examined using MRI.
And here it is, metamory: two bright foci in the prefrontal cortex. One seems to be responsible for remembering recent events, the other for distant ones. And then (how fortunate that the experiment was staged on animals, and not on humans!) The macaques were turned off the corresponding centers of the brain and again forced to bet on whether they had already seen the picture shown or imagined. The results deteriorated significantly. At the same time, as the researchers were convinced of in a separate experiment, the very memory of the viewed pictures has not disappeared. It was just that it was much more difficult for the monkey to confidently say about the unfamiliar picture that she had never really seen it.
This work is a small step towards understanding memory mechanisms. When these mechanisms are unraveled, our descendants will never find themselves in a terrible situation, when a familiar man seems to be walking towards him, but maybe he is not an acquaintance, but just pretended to be. Then people will become happier and more harmonious.
3. The brain sleeps to forget
Some people, especially young people, often think that sleeping is just a waste of time. While we are awake, we learn a lot, accumulate impressions, sometimes even learn something. And then again! - and torn from life eight hours of blackness. And it so happens that you woke up, but you don't remember something of yesterday, for the life of me. Recent articles by researchers from Johns Hopkins University in the United States show that this is actually what we sleep for.
During the day, when the main movement takes place, the brain processes the impressions, remembers them and draws conclusions. Erik Kandel, who received the Nobel Prize for this in 2000, guessed about how this happens approximately. He studied the neurons of the mollusk Aplysia, teaching her simple mollusk lessons (for example, "if you stroke on a siphon, now they will start to beat"). It turned out that this particular lesson corresponds to the growth of one particular synapse, that is, the connection between neurons. So, while we are awake, the brain remembers something, and synapses between neurons grow and strengthen in it.
Well, American neuroscientists say: when the brain is asleep, synapses decrease! That is, not all: the most important and powerful synapses only become angrier, but the secondary nonsense that swelled excessively during waking hours, on the contrary, loses its strength. As a result, mice (it was their brains and neurons that were used in the experiments) “consolidate” memories: they keep important things in their memory and forget unnecessary nonsense. However, the total mass and power of synapses practically does not increase. Thus, the process can be repeated many, many times: learn new things, then sleep, and learn again with a fresh mind. If it were not for this stage of sleep, the synapses in the mouse brain would have grown extremely long before the poor mouse has time to noticeably grow wiser.
The researchers did not limit themselves to such a lapidary conclusion, but unraveled all the main molecular mechanisms involved in this process. If anyone is interested in them, let them read the original articles in Science. And if the reader is already tired of our scientific studies, let him go to sleep: all the synapses that swelled up in his brain while reading the article will dissolve overnight without a trace, and then he will read another note about something else with a fresh mind.