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A new study will contribute to the problem of defining human consciousness. In most cases, a conscious or unconscious person is easy to diagnose. However, in some cases, usually after a serious brain injury, it is difficult to know if a person who does not react is no longer really conscious.
The diagnosis of a person's consciousness can be a matter of life or death when the answer has implications for the type of continuing care that it receives. A new collaborative study collected data on brain activity via a functional MRI of 150 different people at four different sites.
Subtle answers make a huge difference
Each subject was technically unconscious but not the same. 47 healthy subjects saw their brains swept both awake and after being placed under general anesthesia.
The remaining 112 volunteers had all suffered a serious brain injury. This larger group was then divided into a group considered to be in a minimal state of consciousness and a group diagnosed with insensitive sleep state syndrome.
The weakly conscious group was able to show small signs of consciousness, while the non-responder group had awake subjects but showed no signs of voluntary movement. The results of all brain scan data were then compared.
Clear trends emerge from comparing data
Based on the results of fMRI, four well-defined patterns of brain activity have been identified, which are apparently related to cognition. Models are noted by the levels of complex connections between neurons in 42 different regions of the brain; they are formed in a spectrum of more or less complex.
The scientist noted that the most complex 1 pattern 1 was more likely to occur in healthy and awake patients. The least complex model 4 was common in completely unresponsive patients.
The average patterns 2 and 3 appeared with the same frequency in all groups. However, the weakly conscious group had pattern 1 more than in completely insensitive patients.
Definition of consciousness requires attention to the subtle
The researchers noted with interest that subjects with low responsive or vegetative states responding to mental imagery occasionally presented pattern 1. Patients in the vegetative state who did not respond to the disease. Mental imagery did not show a motive sign.
This pattern was also not found in healthy volunteers under sedation.
"This complex pattern disappeared when patients were undergoing deep anesthesia, confirming that our methods were very sensitive to patients' level of consciousness and not to their general brain lesions or their external reactivity," said Davinia Fernández-Espejo, a neuroscientist at the University of Birmingham in the UK, said in an article for The Conversation explaining the work of the team.
The research offers other opportunities for study
The authors say that, although there is still no definitive answer, a careful understanding of the subtle distinctions between schemas and groups offers new possibilities for studying the definition of consciousness.
"In the future, it may be possible to develop ways to externally modulate these conscious signatures and restore some degree of consciousness or responsiveness in patients who have lost them, for example by using stimulation techniques. non-invasive cerebral pains such as transcranial electrical stimulation, "Fernández-Espejo said.
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