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A new study using functional magnetic resonance imaging (fMRI) shows that the picture of the brain of a person in a vegetative state or a state of minimal consciousness is different from the picture of the activity of the brain of a person in consciousness, according to an article published in the journal Science Advances by an international team of neuroscientists. The results of their work show that in contrast to patients in a semi-conscious state, the brain of a healthy person demonstrates high dynamics and significantly more complex connectivity.
“The results of the study show significant progress in determining the ‘fingerprints’ of consciousness in the brain,” says neuroscientist Anil Seth of the University of Sussex, who did not participate in this research project. – “This work opens new doors in the definition of conscious and unconscious States under different conditions.”
A person may be in a state of temporary loss of consciousness (e.g., during sleep or anesthesia) or in a state of complete unconsciousness, such as brain injury. But despite the fact that unconsciousness is defined as the brain’s inability to respond to stimuli, such behavior is not always the result of unconsciousness, some studies say. For example, in the practice of medicine there have been cases where the brain of patients, at first glance does not respond to stimuli, actually showed activity similar to that peculiar to the brain of a person who is in consciousness – they were told to imagine how they perform some physical task, for example, play tennis. Such a mental reaction in the absence of a physical response is called cognitive-motor dissonance.
Such observations force scientists to continue research aimed at understanding what is happening to the human brain during the conscious and unconscious state.
In some earlier studies, monitoring of brain electrical activity using electroencephalography in people who were in a state of sleep, under the influence of anesthesia or after a brain injury, revealed in brainwaves certain patterns that scientists associate with consciousness. However, electroencephalography does not provide complete spatial information about brain activity, says Jacobo Sitt of the Paris Institute for brain and spinal cord research. In turn, using functional magnetic resonance imaging, “we now know where these patterns come from,” the new study says.
Sitt with colleagues, with the support of three medical institutions in Paris, new York and Belgium, Liege conducted an MRI scan of 47 healthy people, as well as 78 patients in a vegetative state (unresponsive wakefulness syndrome, UWS), in which there is no reaction with the preservation of the sleep-Wake cycle (a person lies with open eyes, but does not respond to stimuli), as well as with a state of minimal consciousness (MCS), when a person can follow the eyes of objects, but can not convey his feelings and thoughts.
Computer analysis of MRI scan data obtained on the basis of about 400 images lasting about 20 minutes each for each participant of observations revealed four patterns (pattern) or nature of brain activity. At the same time, as the researchers note, the probability of the manifestation of two certain patterns during scanning directly depended on the diagnosis established by the person.
For example, in healthy people significantly more often than in patients manifested “the first character of activity”, characterized by high spatial complexity and interregional connectivity of the brain, which indicates the coordination of the entire brain. On the other hand, in patients diagnosed with UWS, the first pattern of activity was very rare, but the “fourth”, characterized by reduced spatial complexity and interregional connectivity, on the contrary, was observed most often. Patients with a state of minimal consciousness (MSC) generally demonstrated averaged brain activity, being somewhere in between the two groups. Manifestations of the second and third patterns of activity were observed among all groups of participants.
After that, scientists analyzed the brain activity of another group of people, consisting of 11 patients of one of the canadian hospitals. And again, MRI scan showed the presence of certain types of brain activity. In six patients with UWS, the fourth pattern of activity was most often observed, in the remaining five, who had cognitive-motor dissonance, the first pattern of activity was most often manifested, thereby confirming the conclusions of previous studies (which were mentioned at the beginning of the article), indicating the presence of consciousness in such patients.
According to neuroscientist Tristan Beckinstein of the University of Cambridge, with such a complex sample (patients with different States of brain activity, different medical institutions, different equipment that was used for the study), “the probability of failure of the study was very high.” However, the results were “extremely consistent”, the scientist said.
The ability to identify the signatures of consciousness and unconsciousness can help physicians and relatives to make a difficult choice in favor of continuing or refusing to support the lives of seriously ill patients, says anesthesiologist Anthony Hadz from the University of Michigan. In addition, such an opportunity will allow you to quickly understand the effectiveness or ineffectiveness of certain methods of treatment and rehabilitation.
“In the end, all this leads to a better understanding of what is happening in the brain of such patients in comparison with the brain of healthy people and those who are in a state of consciousness. From this position, this study takes a big step forward,” adds Hades.
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