Can 'Consciousness Change' Under Anesthesia? New Study Investigates
Do we experience consciousness when we are unconscious? According to a new study, published in the journal Current Biology, the answer is "yes and no."
The study shows that conscious changes occur under anesthesia but that the fundamental problem is still unclear.
Heart attack, accident and other trauma victims spend approximately 40 minutes or more unconscious, as anesthesia is a major part of their treatment.
However, whether the victims experience conscious change or consciousness during this period has been a topic of debate.
Several studies have attempted to determine whether consciousness takes place during anaesthesia.
Recently, experts have argued that during anesthesia, the brain does not undergo change. This suggests that consciousness can still occur throughout the entire duration of anesthesia.
Another argument is that consciousness occurs when the brain has stopped responding to the external world, and that the brain is then silent in the absence of activity. In this case, consciousness is likely to occur during unconsciousness, when the brain stops firing.
However, as a recent study by the Eli and Edythe Broad Institute of MIT and Harvard in Cambridge, MA, found, such arguments cannot be objectively tested.
First, the team looked at the internal sensory responses of mice. These responses indicate that the brain is active, but of course, scientists could not study them in the absence of conscious and important information - an intact brain.
The authors of the new study analyzed the sensitive sensory areas of the brains of injured mice that had been treated with a spinal injection.
The researchers looked for electrical activity in these areas and found that they were active during anesthesia, similar to normal conscious activity, but also present for no signs of consciousness.
"Not having an intact brain is probably an artificial limitation of science," says study author Xiaoqing Shen, a postdoctoral researcher at MIT. "Mice can still experience consciousness despite missing brain tissue."
Can consciousness change under anesthesia?
To further investigate the effect of anesthesia on consciousness, the team monitored the brain activity of mice that had been exposed to full anesthesia.
The researchers found that, during anesthesia, the brain still turned on and off.
However, the brain activity resumed once the animals recovered consciousness. During this stage, the brain continued to make normal brain activity.
Further experiments revealed that if the spinal injection technique used in the experiment is used, it actually allowed "a sort of consciousness to increase," although the results were lower.
"The inherent complexity of our brain may explain why consciousness may change in mice on anesthesia," says Dr. Shen.
However, the question of how much consciousness is necessary and whether consciousness is enough - as seems to be the case in humans - remains to be answered.