How Does Anesthesia Take Away Consciousness?

Anesthesia has given medicine a fantastic resource as it has provided patients with the ability to receive painless, for the most part, invasive surgery. It has allowed patients to wake up after surgery having no memory of the operating room or the surgeon's knife. But how does it do this? Anesthesia is not like sleep, as there is no jolting thought or dream to wake you and in sleep you have the ability to retain in your memory.  It provides you with no memories of sometimes hours of unconsciousness and no perception of pain or other surroundings. 

In the article, "What Anesthesia Can Teach Us About Consciousness," the author looks at various ways that anesthesia affects consciousness. She begins with a story about a women on whom anesthesia did not do its proper job. In about 0.13% of anesthesia use, the patients are aware of the procedures and conversations during surgery. These people still appear to be unconscious and cannot communicate with those around them, although they are experiencing the traumatic effects of the surgery. This article investigates ways to improve anesthesia monitoring to prevent these types of error from occurring and also examines anesthesia's effects on consciousness. 

Bor describes in his book, "The Ravenous Brain" examines the opportunity of using anesthesiology to identify the processes missing in the brain when it has no consciousness. Anesthesia allow us to make a map of sorts to lay out the potential location and movements of consciousness, as it has been discovered that consciousness does not live within one part of the brain. Bor seems confident and enthused about anesthesia's potential contribution the knowledge about the consciousness in the brain. 

There is not much information about the neurological impacts of anesthesiology and knowledge about consciousness is also very limited in that we don't know exactly what it is nor how the brain creates or monitors it. However, there have been some studies that provide basic knowledge about the brain electrical signaling in the unconscious and conscious brain in strives to find neural correlates to consciousness. The article describes these experiments as such: The brain was compared in its spectrum, awake, asleep, drugged with anesthetics, and in comas or suffering from "locker - in syndrome." It was found then when electrical stimulus was applied, the awake brain showed the stimulus was able to travel all around the brain, while the unconscious brain showed the stimulus remained localized and then faded away. This lead investigators to believe that consciousness requires both synthesis and integration of information from numerous and distance parts of the brain. 

These experiments involving consciousness provide a potential ground work for fixing those problems, mentioned above, with anesthesia. Because consciousness is represented by the electrical signal dispersing throughout the brain, the author of this article suggest that instead of the magnitude of electrical stimulus being monitored during surgery, electrical signal movement be monitored. This would allow observers to see whether or not the patient is truly unconscious and not catatonic while maintaining awareness. If the electrical stimulus remain localized, the patient would clearly be unconscious and unaware. 

Further studies were examined in the article that looked at the concept of recurrent processes. These are described as loops between sensory areas and higher-level parts of the brain associated with processing information. These studies found that these recurrent processes were not present in any form in the unconscious brain. This evidence began to lead to the idea that unconsciousness removes the brain's ability to communicate within itself. It was found that although sensory parts of the unconscious brain are locally function, they are not able to undergo intrabrain communication. 

This evidence is reinforced in Bor's text. He looks at the affects of anesthesia on the brain stem, limbic system, and cortices. In the brain stem, Bor came to the conclusion consciousness has no real effect because its processes remain functional during anesthesia. In the limbic system and cortices, Bor found that they only demonstrated localized functions during anesthesia and were unable to communicate to other parts of the brain. Therefore consciousness here is impossible while under anesthetics. 

Bor also described a study that looked at patient's retention of information while under anesthesia. As an example people were told the word "ashtray" while in surgery and then after surgery asked to finish the incomplete word "ash." Significantly people chose the word "astray" over other words beginning with "ash." The same study was conducted where the definition of a word was said during surgery, but those results were not significant and showed the limitations of our learning ability while under anesthesia. This experiment shows that although anesthesia causes unconsciousness the body is still partially aware as it can remember somewhere deep in the brain, that this word has been presented previously. 

In summary, it is clear the anesthesia does not work fully to prevent consciousness. The fact that some patients remain aware during surgery and that others are able to be primed for the sound of a word show that consciousness is somehow able to remain present, in even the slightly manner. "What Anesthesia Can Teach Us About Consciousness" provides a generous and intelligent outlook on how to improve removing consciousness from patients during surgery. Bor's parallels provide a thought that perhaps consciousness cannot be fully taken away through any methods. Bor's findings and the experiments described in the article also give the hope that consciousness can potentially be identified in synthesis, functions, and location through the use of anesthesia. Only time will provide the answer to this intriguing hypothesis about conscious as this topic presents a lot to think about moving forward. 

Bor, Daniel. The Ravenous Brain: How the New Science of Consciousness Explains Our Insatiable Search for Meaning. New York: Basic, 2012. Print. 

Koerth-Baker, Maggie. (2013) What Anesthesia Can Teach Us About Consciousness. The New York Times, Magizine. http://www.nytimes.com/2013/12/15/magazine/what-anesthesia-can-teach-us-about-consciousness.html?pagewanted=all&module=Search&mabReward=relbias%3Ar.