The new vision of the brain – Magazine ?

Scientists who study the functioning of the brain today have techniques that allow them to visualize the activity of that organ when the individual performs different actions. These techniques have led them to radically change their ideas about the organization of the brain.

Until relatively recently, brain scientists assumed that the cerebral cortex—the outer layer of the brain, where complex brain functions such as memory, attention, consciousness, and language take place—could be divided into zones. well defined, corresponding to the different functions: one area for language, another for consciousness, another for visual perception… without intersection or overlap. Higher functions such as consciousness and learning were assumed to operate independently of the brain regions responsible for, for example, muscle movement or instinctive emotional responses. Research from the last 10 years, however, indicates that the areas of the brain are not so delimited and that they act simultaneously. The rationality and capacity for knowledge that characterize our species result from the integrated activity of the entirety of our brain.

History of a cup

For example, according to the previous view of the organization of the brain, when you picked up a cup, the visual information about its vision, position and shape passed from the posterior areas of the cerebral cortex, where perception occurred, to the frontal cortex, seat of the brain. rational thinking and decisions. There the information was integrated to plan the muscle movements necessary to take the cup. Once these processes were carried out, the order was given to the motor cortex, which controls muscle movements. And after all that, you already had the cup in your hand. Or not?

For many years Giacomo Rizzolatti, director of the Department of Neuroscience at the University of Parma and his team of researchers, have carried out studies on which neuron systems are involved in each movement. And they realized that there is a type of frontal motor neurons that actively contribute to creating a rapid and simultaneous response to the information we are receiving from the environment at all times. That is, these neurons do not have a passive role, but rather an executor role in the actions. For example, it is now known that for our hand to simply grasp the cup, it needs a mechanism capable of translating the sensory information it receives into the way the fingers will grasp it. Many would have the impression that the first process follows the second, but thanks to current research on the neurons of the motor cortex of the brain it is known that both are simultaneous.

Mirrors in the brain

In other studies, carried out in the 90s, Rizzolatti and his collaborators discovered by chance a type of motor neurons with unexpected behavior. The Italian scientists were studying a region of the motor cortex of macaque monkeys that controls hand movements. Their devices allowed them to record the activity of individual neurons. When the monkey grabbed food to put in its mouth, the neuron activated in a certain way, which manifested itself as a pattern of electrical impulses. Then the researchers realized that the monkeys’ neurons were activated in the same way when they saw one of the scientists pick up food and put it in his mouth! After ruling out other possibilities, Rizzolatti and his collaborators concluded that these neurons served to represent actions in the monkey’s brain, regardless of whether the animal was the agent or just a witness to the action. Rizzolatti and his team called these brain cells mirror neurons and they also found them in the human brain. Mirror neurons provide an internal representation of actions, both our own and others, and are responsible for behaviors such as recognition and imitation. They could also be behind empathy (the ability to vividly represent what others are feeling, both physically and emotionally) and perhaps even our ability to imitate sounds. There is only one step from there to concluding that they are involved in language acquisition.

Imitation and communication

In the 1950s, the American linguist Noam Chomsky postulated a theory to explain why children learn to speak so quickly despite the insufficient stimulation provided by the environment. Chomsky proposed that all languages ​​in the world comply with a kind of universal grammar, a series of rules so general that they apply to all languages. Children do not have to learn this universal grammar; They bring it programmed in the brain by evolution. Learning a specific language is simply reduced to adjusting certain parameters of universal grammar. A couple of years of receiving examples are enough for the child to master his native language. This has generated the idea that language is not a consequence of communication over generations, but rather an instinctive behavior similar to building a nest in birds. The architecture of the nest is innate knowledge, just like the structure of human languages.

In more recent years, Canadian psychologist Steven Pinker has taken Chomsky’s idea as the basis of his study of language acquisition in children. Pinker titled his book, in which he gives experimental foundations to Chomsky’s model, The language instinct. The existence of a language instinct is confirmed, for example, in sign languages ​​that have arisen spontaneously in deaf-mute communities isolated from the rest of the world. In those communities, deaf and mute people have in a couple of generations developed manual sign systems with all the characteristics of spoken languages ​​(in fact, a country’s sign language usually does not remotely resemble its spoken language). This and studies of human fossils, as well as comparative anatomy between the phonetic apparatus of primates and humans, led to language beginning to be studied not only as a product of the mind, but as a physical activity. Scientists began to understand that language depends heavily on neurons in the cerebral cortex that control muscles, particularly breathing.

Primates, and especially humans, have relatively fine control of the hands and fingers, as well as the muscles of the face, which is because there is a direct connection between the motor cortex and the muscles that control these parts. of the body. In humans the reaches of the motor cortex extend to a group of motor neurons known as ambiguous nucleus, which controls the movement of the larynx, and another that controls the costal muscles that are involved in breathing. Since other primates lack these connections, it is believed that our species acquired them by evolution in relatively recent times.

I accompany you in your pain (or in your pleasure)

In the human brain the mirror neuron system is more widespread than in that of monkeys. People’s mirror neurons are also capable of identifying the intention of an action from the context in which this action is carried out, as demonstrated by another experiment by Rizzolatti and his collaborators, together with the team of Marco Iacoboni, from the University of California at Los Angeles. The researchers recorded the activity of the mirror neurons of people who were shown several short films: in one of them, a hand was holding a cup, in two others a table was seen set up for tea and the same table after tea. ; Finally, in others the hand was seen taking the cup in these two contexts (before tea and after tea). The team observed that the participants’ mirror neurons showed more activity when the hand removed the cup from the tea table and less activity when the hand removed it from the dirty table. This suggests that mirror neurons distinguish between lifting the cup to drink the contents and lifting it to clean the table, perhaps because drinking is the more immediate and frequent intention. The mirror neuron system, apparently, allows us to decipher the intentions of others, although this does not depend only on them, but on many other factors, such as memory, experience and beliefs, for example.

The representative function of mirror neurons could explain why we get excited when watching a soccer game or a play. Indeed, these neurons participate in our ability to understand the emotions of others. To explore this idea, Rizzolatti collaborated with a French team in experiments in which participants were subjected to an unpleasant odor and their brain activity was recorded. The activity was similar in people who experienced the sensation of disgust and in those who only saw others making expressions of disgust.

The English theater director Peter Brook believes that the discovery of the function of mirror neurons in people explains a phenomenon known to theater people since ancient times: catharsis, through which our senses and perceptions come into resonance with those of the actors, making us identify with the dramatic situation they are representing. For all this, mirror neurons are also known as empathy neurons, although this does not depend only on the mirror neuron system.

The moral brain

Much of human interaction depends on our ability to understand and share the emotions of others. But feeling empathy with the emotions of others does not necessarily lead us to react like them, since our emotional relationships are very complex.

In June of last year, the magazine Science & Life published a report on the investigations…