Finnish researchers have gained new information on brain activity during general anaesthesia by recording changes in the electrical activity of the brain. They discovered that changes in electroencephalogram correlated with the loss of consciousness itself and also by the non-specific effects of the drugs. Nearly all participants recalled dreaming during unresponsiveness and, somewhat surprisingly, words presented during anaesthesia were still processed in the brain even though the participants were unable to recall them later.
When people are administered an anaesthetic, they seem to lose consciousness – or at least they stop reacting to their environment. But is consciousness lost fully during anaesthesia or does consciousness persist in the brain but in an altered state?
This question has been explored in the joint research project “The Conscious Mind: Integrating subjective phenomenology with objective measurements” of the University of Turku and the Hospital District of Southwest Finland studying neural mechanisms of human consciousness. In the study, the changes caused by the anaesthetics were monitored with electroencephalogram (EEG) and positron emission tomography (PET).
The study is a joint project between the research group of Adjunct Professor of Pharmacology and Anaesthesiologist Harry Scheinin studying anaesthesia mechanisms, and the research group of Professor of Psychology Antti Revonsuo studying human consciousness and brain from the point of view of philosophy and psychology.
The study was conducted in collaboration with investigators from the University of Michigan, Ann Arbor, and the University of California, Irvine, USA. The latest research findings in the project have been published as four different publications in the July issues of the two leading journals in anaesthesiology. The main funders of the project are the Academy of Finland and Jane and Aatos Erkko Foundation.
Photo by Sara Jarret, CMI