For over a century, doctors have been inducing patients into reversible comas by way of anesthesia. 60,000 people a day undergo general anesthesia in the United States alone. What makes this factoid even more interesting is that scientists are still unsure about just what goes on inside the brain when under the effect of anesthesia.
The relation between anesthesia and unconsciousness
It is presently unclear how anesthesia drugs affect the brain’s circuitry. Is it the same pathways used when we sleep? Do the drugs produce a similar signal as when we lose consciousness? Do parts of our brains completely shut down, or do they just stop communicating with one another? And does anesthesia have the same effects on our brains as meditation or hypnosis, or even a post-injury coma?
Even though they know how to safely transition patients from consciousness to unconsciousness and back again, they “why” still eludes them.
MIT neuroscientists are currently delving in to what happens to the brain when under anesthetic drugs, because they believe that a better understanding of the process will lead to safer and more effective anesthetic practices.
But the “how” is observable
Anesthesiologists essentially perform natural experiments every day when they anesthetise patients and monitor them as their consciousness disappears. They actually have the ability to influence how and when patients lose their pain perception, movement ability, memory, and awareness by varying dosage amounts and drug types.
Scientists consider each of these affected areas as separate pieces to a complicated brain jigsaw puzzle, as bit by bit, they are piecing together to get a better understanding of human consciousness. What they’ve found by observing consciousness recede is that the brain doesn’t shut down all at once. Rather, there is a hierarchy and graduation to when each part of the brain goes to sleep, as well as when the brain wakes up.
Is the brain sleeping? Or is it just not talking?
By use of an electroencephalogram (EEG), studies are suggesting that anesthesia interferes with the brain’s internal communication, and feedback between the front and back areas of the brain is interrupted. They have also found that the anesthetised brain is still responsive to stimuli, but it is somehow just not processed as input necessary for conscious awareness.
We will examine in more detail what happens inside an anesthetized brain in Part 2 of this series.