The brain of the townspeople and people living in the village reacts differently to stressful situations, scientists from Canada and Germany write in an article published Thursday in the journal Nature.
Life in the city, on the one hand, increases the risk of various diseases, but it also has advantages: inhabitants of policies usually earn more living in rural areas, here modern methods of treatment are more accessible. However, from the point of view of mental health, citizens are much more vulnerable than the villagers: neurotic and mental disorders, in particular, schizophrenia, are much more common among the former.
Group led by Andreas Meier-Lindenberg from the University of Heidelberg (Germany) decided to investigate the biological mechanisms that are behind the increased mental vulnerability of citizens.
To do this, scientists with the help of functional magnetic resonance imaging investigated how the brains of people with varying degrees of “urbanization” react to stress – from those born in the city to those who arrived there at a mature age.
In the course of the experiment, 32 volunteers had to press the buttons to choose the correct answers to the arithmetic problems that appear before their eyes on the displays of special glasses, under severe time constraints. The researchers at the same time through the headphones “criticized” them for poor performance of the task.
The stress level of the subjects was monitored at different stages of the experiment by measuring the content of the hormone cortisol in saliva, as well as pressure and pulse.
It turned out that in people with varying degrees of urbanization, different parts of the brain are activated in response to stress. For subjects currently living in the city, the stress “included” the amygdala in the brain, with the degree of activation increasing, from low in those living in small towns to much higher in those living in megalopolises.
In subjects who grew up in the city, but moved to the countryside, the center of activity under stress was located in another area of the brain – the cortex of the gyrus, which controls the emotional state.
“This discovery means that different regions of the brain are sensitive to the experience of living in a city at different periods of life,” says one of the authors of the study, Jens Prussner (Jens Pruessner) of Canadian McGill University.
According to him, this work allows us to better understand the risks that the urban environment poses to people’s mental health. Scientists intend to further explore the relationship between the observed effect and mental disorders.
The brain of the townspeople and the village reacts differently to stress
Life in the city is associated with an increased risk of increased anxiety, depression and schizophrenia, reports Live Science. Testing the brain of students who grew up or live in large cities allowed scientists from the University of Heidelberg (University of Heidelberg), Germany, to determine which parts of the brain are responsible for the stress response to the urban environment and lifestyle. Their article was published on June 22 in the journal Nature.
It has long been known that life in the city as a child two or three times increases the likelihood of developing schizophrenia, and a person who migrates to the city as an adult increases the risk of heightened anxiety and other personality disorders by 21% compared with rural residents.
To establish how the city changes the human brain, scientists scanned German students at a time when they were under severe stress: they were asked to decide an exam in which they could give no more than a third of the correct answers. The students were informed that they had passed the worst exam, and they also put pressure on them, constantly reminding them how important it is to pass the exam well.
It turned out that students who lived in urban conditions, in response to stress, increased activity in the anterior part of the cingulate gyrus of the cerebral cortex, and those who lived in cities in early childhood, increased activity in the amygdala. Both of these sites are responsible for the reaction to stress and in many ways help each other work. The researchers considered the behavior of the brain of a rural resident to be normal.
Now scientists want to establish what the urban environment should be so as not to cause a stress reaction in the brain. Their theory is that increasing the number of green areas and a more environmentally friendly environment can significantly reduce the pressure on the urban dweller, and thus improve his mental health.
However, the environment in which a person is located only increases the risk of developing mental illness. The causes that cause these diseases are most likely related to genetics. According to Around the World, a team of scientists led by Professor Douglas Blackwood (Douglas Blackwood) from Edinburgh University (University of Edinburgh) Scotland allegedly found a gene responsible for mental illness
It turned out that people suffering from schizophrenia, clinical depression or bipolar disorder, “silent” gene ABCA13. Two years ago, scientists from the Institute of Neurology in London (Institute of Neurology in London) and their colleagues discovered the genes responsible for the occurrence of dementia (dementia). This common disease is caused by damage to the GAB2 gene, which is usually associated with the APOE4 gene.
Brain electrical stimulation can cause symptoms of schizophrenia
Simple electrical stimulation of certain parts of the cerebral cortex can cause obtrusive hallucinations in a patient, resembling the symptoms of schizophrenia. An unusual effect was discovered and described by the staff of the Swiss State Polytechnic School. A study report published in the journal Nature.
A strange side effect was observed in the treatment of a 22-year-old woman who suffered from epilepsy and who had no previous mental health problems. The patient was trained for surgery to remove the epileptic seizure-causing scar tissue formed after a brain injury.
Trying to determine the center of epileptic activity as precisely as possible, the doctors applied electronic impulses to the patient’s brain. During the examination, the electrode accidentally touched the temporal-parietal region of the cortex, which is responsible for coordinating the body data in space to the brain. As a result, the patient had a steady feeling of the presence of a dark figure behind her back, copying the movements of her body.
The doctors who treated the woman decided to understand what was happening and repeated electrostimulation of the temporal-parietal region several times. Every time the impact caused the illusion of the presence of the “alien” figure in the patient. When the lying patient was asked to hug her knees, she had the impression that the dark figure was trying to hug her. Despite the fact that the patient was fully aware that what was happening was an illusion, her feelings were very realistic and frightening.
The patient “stranger” standing behind his back and copying the movements seemed to her to be a completely independent person, in no way connected with her body and consciousness.
According to the coordinator of the research project, the illusion recorded during the research can be explained by the projection of information coming in to the brain about the position of the patient’s own body under the influence of electrical impulses.
Observation results clearly indicate that relatively simple switching of electrical signals in the brain can cause complex psychiatric symptoms in mentally healthy people, notes Dr. Blanque. It is possible that a similar mechanism underlies such symptoms of schizophrenia as a split personality, an obsessive sense of subordination to someone else’s will, the perception of members of their own body as belonging to others, etc.
In the near future, scientists are going to reproduce the observed effect in clinical studies involving several healthy volunteers.