A new study using functional magnetic resonance imaging (fMRI) shows that the picture of the brain of a person in a vegetative state or minimal consciousness state different from the pattern of activity of the human brain, in consciousness, says the article, published in the journal Science Advances by an international team of neuroscientists. Their results show that in contrast to the patients in a semi-conscious state, the brain of a healthy person shows a high dynamics and significantly more complex connectivity.
“The results of the study demonstrate significant progress in the definition of “fingerprints” of consciousness in the brain,” says neuroscientist Anil Seth from University of Sussex, have not participated in this research project. “This work opens a new door in the definition of conscious and unconscious States under various conditions”.
A person can be in a state of transient loss of consciousness (e.g., during sleep or anesthesia), or fully unconscious, 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 unconsciousness, say some studies. For example, in the practice of medicine there have been cases when patients at first glance and don’t react to stimuli, in fact, demonstrated activity similar to that characteristic of the human brain, being in mind – they were told to imagine that they perform some physical task, such as playing tennis. Such mental reaction in the absence of physical answer is called the cognitive motor dissonance.
Similar observations have scientists continue research aimed at understanding what happens to the human brain during conscious and unconscious state.
In some earlier studies monitoring the brain’s electrical activity using electroencephalography in humans who were asleep, under the influence of anesthesia or after the experienced traumatic brain injury, were detected in the brain waves of certain patterns which scientists have linked to consciousness. However, the EEG does not allow one to obtain full spatial information about brain activity, says Jacobo Sitt from the Parisian research Institute of brain and spinal cord. In turn, using functional magnetic resonance imaging, “now we know what causes these patterns,” according to a new study.
Sitt with colleagues and is supported by three medical institutions in Paris, new York and Belgian Liege conducted MRI scans of 47 healthy people and 78 patients in a vegetative state (unresponsive wakefulness syndrome, UWS), in which there is a lack of reaction with preservation of the cycle of sleep-wakefulness (a man lying with open eyes, but did not respond to the stimuli) as well as a state of minimal consciousness (MCS), where people can track objects, but cannot convey their feelings and thoughts.
Computer analysis of MRI scans obtained on the basis of about 400 images with a duration of approximately 20 minutes each for every participant observations revealed four patterns (pattern) or pattern of activity of the brain. However, as the researchers note, the probability of two specific patterns when scanning directly dependent on the established human diagnosis.
For example, in healthy people significantly more often than patients manifested “first nature activity”, characterized by high spatial complexity and interregional connectivity of brain areas, which indicates the coordination of the work of the brain. On the other hand, in patients diagnosed with UWS the first pattern of activity was shown very rarely, but “the fourth”, which is characterized by reduced spatial complexity and regional connectivity, on the contrary, was observed most often. Patients with state of minimal consciousness (MSC) generally showed average activity of the brain, being somewhere in the middle between the two groups. Manifestations of the second and third pattern of activity was observed among all groups of study participants.
Then the scientists analyzed the brain activity of another group of people, consisting of 11 patients from a canadian hospital. And, again, the MRI scan showed the presence of certain characters of brain activity. Six patients with UWS were most common fourth pattern of activity, the remaining five who have had cognitive motor dissonance, often manifested the first pattern of activity, thus confirming the findings of previous studies (as mentioned in the beginning of the article), pointing to the presence of consciousness in these patients.
The first (left) and fourth (right) patterns of brain activity detected with MRI scanning
According to neuroscientist Tristan Bekinschtein from the University of Cambridge, with such a complex sample (patients with different States of brain activity, different medical institutions, different equipment used for research) “the probability of failure of the study were very high.” However, the results were “very consistent”, said the scientist.
The ability to identify the signatures of consciousness and unconsciousness may help physicians and families to make difficult choices in favor of the continuation or refusal of life support of seriously ill patients, said the anesthesiologist Anthony Hudec from the University of Michigan. In addition, the opportunity will 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 these patients compared to the brains 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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