Despite its potential risks, general anesthesia and how it leads human brain to unconsciousness is still not known. A POSTECH research group has been investigating the nature of consciousness as well as control of the level of consciousness through anesthesia, whose effort has drawn much attention of the academia.

Professor Seunghwan Kim (Department of Physics) and his team, in a joint study with POSTECH graduate Doctor UnCheol Lee of University of Michigan and a Seoul Asan Medical Center team, have presented evidence that the transition from consciousness to unconsciousness occurs by the suppression of the information flow channel in the brain through experimentation with general anesthesia.

The research group derived general anesthesia from injecting propofol into normal people and measured the amount and the direction of information flow both in the frontal lobe, which takes charge of recognition, and in the occipital lobe, which processes sensory information. The result was that the information flow from the frontal lobe toward the occipital lobe decreases at the same time the patient becomes unconscious but the flow in the opposite direction keeps uniform at all times.

This indicates that the information processing which deals with senses from the outside before unconsciousness is performed constantly in the patient’s brain under the general anesthetic state, but the information processing after unconsciousness is strongly suppressed. Also, this result is expected to be applied to a new index development to prevent accidents such as awakening during surgery. “Through our research, we have found the clue to solve the many puzzles of consciousness, such as the transitional process from consciousness to unconsciousness,” said Professor Kim.

The team also identified that each individual has his/her own distinctive patterns in brain activity, both in conscious and unconscious states. This provides scientific proof for the fact that there exist individual differences in emotional reaction to the same situation such as watching the same movie or experiencing the same social and environmental circumstances.

The world-renowned anesthetist Anthony Hudetz of the University of Wisconsin remarked, in the commentary for the POSTECH team’s research, that the findings of the study “opened up a new door to the neurological understanding of anesthesia and consciousness.”

The results are expected to contribute to the investigation of the existence and role of the peculiar information flow system in not only the unconscious but also many forms of the conscious state including brain dead, vegetative, sleeping and epileptic.

The findings were introduced as the Target Paper in Consciousness and Cognition, Volume 18, Issue 4 (1069-1078).