Although anesthesia is an extremely common and crucial part of the world of medicine today, there are still many unanswered questions about how it actually works. Many aspects of anesthesia are constantly being researched and explored, and new discoveries are constantly being made. One question that is often asked by patients and physicians alike, is are you partly conscious under anesthesia? A new study performed by 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, aims to answer this common question. The first part of this study involved healthy adults who were anesthetized with dexmedetomidine or propofol, while being monitored with an electroencephalogram (EEG) and a positron emission tomography (PET). The drugs were given to the subjects until they had just almost lost responsiveness. They could then be woken up with loud talking or a light shake. As soon as the person regained responsiveness, they were asked if they experienced anything during their time under anesthesia. Nearly all the participants said they experienced something similar to a dream. The subjects also were played sentences, half which ended normally and half that ended in a strange way. One unexpected sentence, for example, was “The night sky was filled with shimmering tomatoes”. If the subject heard the strange sentence when they were awake, a reaction would show on the EEG. However, when they were under anesthesia, their brains could not tell the difference between the normal and strange sentences. The activity on the EEG did show, however, the brain was trying to interpret the meaning of the words. When the patients woke up from the anesthesia, they had no memory of the sentences. The subjects in this study were lastly played very unpleasant sounds while they were under anesthesia. When they woke up, they were played these sounds, along with others that had not been played before. The participants reacted quicker to the sounds that had already been played. So can we answer the common question are you partly conscious under anesthesia? The results of this study has lead researchers to believe that consciousness is not completely lost when a patient is put under anesthesia, even though the person is not reacting to what is happening around them. The brain may try to understand words and register speech while under anesthesia, but they will not remember when they are woken up and regain full consciousness. “The state of consciousness induced by anaesthetics can be similar to natural sleep. While sleeping, people dream and the brain observes the occurrences and stimuli in their environment subconsciously” summarises Professor Revonsuo. “Anaesthesia could resemble normal sleep more than we have previously thought” adds Dr. Scheinin. While this topic will continue to be researched, these findings are extremely helpful to doctors and patients hoping to understand anesthesia a bit more.
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