New research usingfunctional magnetic resonance imaging (fMRI) shows that the picture of the brain of a person in a vegetative state or state of minimal consciousness differs from the picture of the activity of the brain of a person who is conscious, 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 who are in a semi-conscious state, the brain of a healthy person exhibits high dynamics and significantly more complex connectivity.
"The research results demonstratesignificant progress has been made in determining the “fingerprints” of consciousness in the brain, ”said neilbiologist Anil Seth of the University of Sussex, who did not take part in this research project. “This work opens new doors in defining conscious and unconscious states under various conditions.”
A person may be in a state of temporaryloss of consciousness (for example, during sleep or anesthesia) or in a completely unconscious state, for example, when receiving a brain injury. But despite the fact that unconsciousness is defined as the inability of the brain to respond to stimuli, such behavior is not always the result of an unconscious state, some studies say. For example, in the practice of medicine, there were cases when the brain of patients, seemingly unresponsive to stimuli, actually showed an activity similar to that characteristic of the brain of a conscious person — they were told to imagine how they perform some physical task. for example, play tennis. This mental reaction in the absence of a physical response is called cognitive-motor dissonance.
Such observations cause scientists to continue research aimed at understanding what is happening to the human brain during a conscious and unconscious state.
In some earlier studies, monitoringelectrical activity of the brain using electroencephalography in people who were in a state of sleep, under the influence of anesthesia, or after experienced traumatic brain injury, revealed certain patterns in brain waves that scientists associate with consciousness. However, electroencephalography makes it impossible to obtain complete spatial information about brain activity, says Jacobo Sitt of the Paris Institute of Brain and Spinal Cord Research. In turn, with the help of functional magnetic resonance imaging, "we now know where these patterns come from," the new study says.
Sitt with colleagues supported by three medicalinstitutions in Paris, New York and Belgian 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 a lack of reactions with the preservation of the sleep-wakefulness cycle (a person lies with eyes open, but completely unresponsive to stimuli), as well as with the state of minimal consciousness (MCS), when a person can follow the eyes of objects, but cannot 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 (patterns) or patterns of brain activity. At the same time, as the researchers note, the probability of the manifestation of two specific patterns when scanning directly depended on the diagnosis made by the person.
For example, healthy people are significantly more likely thanthe patients showed “the first character of activity”, characterized by a high spatial complexity and interregional connectivity of the brain, indicating coordination of the whole brain. On the other hand, in patients with a diagnosis of UWS, the first pattern of activity was very rare, but the “fourth” pattern, characterized by reduced spatial complexity and interregional connectivity, on the contrary, was most often observed. Patients with a state of minimal consciousness (MSC) generally demonstrated averaged brain activity, being somewhere in the middle between the two groups. Manifestations of the second and third patterns of activity were observed among all groups of study participants.
After that, the scientists analyzed the activitythe brain of another group of people, consisting of 11 patients from a Canadian hospital. Again, an MRI scan revealed the presence of certain patterns of brain activity. In six patients with UWS, the fourth pattern of activity was most often observed, in the remaining five, in whom cognitive-motor dissonance was noted, the first pattern of activity was most often manifested, thus confirming the findings of previous studies (mentioned at the beginning of the article) that indicated the presence of consciousness in such patients.
The first (left) and fourth (right) patterns of brain activity detected by MRI scan
According to neuroscientist Tristan Beckinstein fromCambridge University, 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 notes.
The ability to identify signatures of consciousness andunconsciousness can help physicians and relatives make the difficult choice in favor of continuing or refusing to support the lives of seriously ill patients, according to anesthesiologist Anthony Hadets of the University of Michigan. In addition, this opportunity will allow you to quickly understand the effectiveness or inefficiency of certain methods of treatment and rehabilitation.
"In the end, all this leads to a better understandingwhat is happening in the brain of these patients in comparison with the brain of healthy people and those who are in a state of consciousness. From this position, this study makes a big step forward, ”adds Hadets.
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