Scientists Solving the Mystery of Human Consciousness
Scientists solving the mystery of human consciousness
Primitive consciousness emerges first as you awaken from anesthesia
Awakening from anesthesia is often associated with an initial phase of delirious struggle before the full restoration of awareness and orientation to one’s surroundings. Scientists now know why this may occur: primitive consciousness emerges first. Using brain imaging techniques in healthy volunteers, a team of scientists led by Adjunct Professor Harry Scheinin, M.D. from the University of Turku, Turku, Finland in collaboration with investigators from the University of California, Irvine, USA, have now imaged the process of returning consciousness after general anesthesia. The emergence of consciousness was found to be associated with activations of deep, primitive brain structures rather than the evolutionary younger neocortex.
These results may represent an important step forward in the scientific explanation of human consciousness. The study was part of the Research Programme on Neuroscience by the Academy of Finland.
“We expected to see the outer bits of brain, the cerebral cortex (often thought to be the seat of higher human consciousness), would turn back on when consciousness was restored following anesthesia. Surprisingly, that is not what the images showed us. In fact, the central core structures of the more primitive brain structures including the thalamus and parts of the limbic system appeared to become functional first, suggesting that a foundational primitive conscious state must be restored before higher order conscious activity can occur” Scheinin said.
Twenty young healthy volunteers were put under anesthesia in a brain scanner using either dexme-detomidine or propofol anesthetic drugs. The subjects were then woken up while brain activity pictures were being taken. Dexmedetomidine is used as a sedative in the intensive care unit setting and propofol is widely used for induction and maintenance of general anesthesia. Dexmedetomidineinduced unconsciousness has a close resemblance to normal physiological sleep, as it can be reversed with mild physical stimulation or loud voices without requiring any change in the dosing of the drug. This unique property was critical to the study design, as it enabled the investigators to separate the brain activity changes associated with the changing level of consciousness from the drugrelated effects on the brain. The staterelated changes in brain activity were imaged with positron emission tomography (PET).