In the past few years, the concept of the human brain has changed dramatically. Scientists have proven that the center of rationality and self-control is in the frontal lobe of the cortex, and hormones control mood and behavior. RIA Novosti investigates whether people are capable of conscious decisions or their actions - the result of biochemical reactions in the brain.
In 1979, American psychologist Benjamin Libet showed experimentally that the parts of the brain responsible for making decisions are activated earlier than a person makes his choice. We are talking about two hundred milliseconds, but it was they who transferred the issue of free will to the natural science plane. Libet's experiment was widely criticized, however, reproduced dozens of times, it gave the same results.
Another attempt to verify Libet's conclusions was made in 2016 at Johns Hopkins University (USA). Scientists placed subjects in an MRI machine and asked them to randomly move their gaze from one part of the screen to another (the monitor was inside the machine). Every eye movement was recorded in the picture. When a person changed the direction of gaze, the parietal lobe of the brain, which is responsible for implementing decisions, was activated. However, two regions of the brain - in the frontal lobe of the cortex and in the basal nuclei - were excited before the gaze began to change direction. It turns out that the decision to take action matures in the brain before the person realizes his choice.
Love, friendship, hormones
In an attempt to explain this, neuroscientists suggested that chemical processes in the brain control a person's mood and behavior, including decision making. The human brain weighs about one and a half kilograms, its volume is on average one and a half thousand cubic centimeters, but we think only a few centimeters of the cortex. The rest of the nervous tissue is involved in the processing of non-verbal information coming from the external environment and from the body itself. Therefore, hormones synthesized in the ovaries, adrenal glands or other endocrine glands through their metabolites (products of chemical conversion in the body) affect the brain and thus determine human behavior.
Thus, stress hormones - adrenaline, norepinephrine and cortisol - inhibiting digestion and improving blood supply to muscles, forcing a person in a difficult situation to act according to one of two stable behavioral patterns: "fight or flight" and "freeze". Levels of another hormone, progesterone, whose main function is to prevent uterine contractions during pregnancy, reduces anxiety in the pregnant woman and thereby protects the embryo from harmful stress hormones. The same hormone is responsible for mood swings in women, when at the end of the menstrual cycle there is less of it in the body.
Another predominantly female hormone - oxytocin - increases the production of breast milk, awakens parental feelings for the baby. In addition, it is associated with social networking and anxiety levels, which is why people try to use it to treat depression. For example, scientists from St. Petersburg University experimentally found that oxytocin returned rats exposed to uncontrolled stress to normal, while conventional antidepressants did not help.
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Maternal share
Sexual orientation, intellectual potential, autism, schizophrenia, aggression are laid in the embryo under the influence of hormone levels in the mother's body, says the Dutch neurophysiologist Dick Swaab, author of the book "We are our brain."
Thus, a high level of testosterone during pregnancy, the use of nicotine, amphetamines and some synthetic hormones by the expectant mother can lead to a homosexual orientation of a female child. And a boy's sexual behavior depends on how many brothers he has. The fact is that with each new male embryo, the female body produces more and more substances that counteract its hormones.
Articles by Svaab and his colleagues, published in leading scientific journals, were taken into account in the development of legislation in the UK and the European Court of Human Rights, when transsexuals defended the right to change the gender in the passport. Another example of the practical application of the results of scientific research in the field of neurobiology is described by Professor Nita Farahani of Duke University (USA). Her research team analyzed more than 1,500 court sentences in the United States from 2005 to 2012, and in about half of them found references to neurobiological data when the defense tried to prove that the brain of the defendants made them commit a crime.
According to Michael Gazzanig, a neuropsychologist at the University of California, Santa Barbara, the fact that brain biochemistry influences behavior does not relieve a person of responsibility for their actions. In the book "Who is in charge?" he writes that at the level of the brain of one person, free will is a myth created by evolution, but at the level of interaction between people it is a very real thing. It is impossible to fully predict the behavior of people in relation to each other, and thanks to this, free will arises, which allows the human brain to constantly develop and improve.
Alfiya Enikeeva
