Consciousness and Unconsciousness

Scientists are still trying to learn what consciousness is. Its puzzle is still incomplete. It’s still unknown how consciousness rises in the brain. Doctors and many other qualified people who how to knock a person out quickly. “Yet, for nearly two centuries our ignorance has not hampered the use of general anethesia for routinely extinguishing consciousness during surgery.” Researchers have used anesthesia, recently in combination with brain scans, as a tool to see what happens in the brain when people fade in and out of consciousness — which parts turn on and which turn off. For example, in a study published in the April 4 issue of The Journal of Neuroscience, investigators showed that a person could respond to a command to open his eyes when higher parts of the brain were not yet turned on. This finding may be useful in deciding how to measure the effects of anesthetics, and adds another data point to the knowledge of what’s going on in the brain. In previous studies, the researchers, led by Harry Scheinin and Jaakko W. Langsjo of the University of Turku, in Finland, and Dr. Alkire found that the brainstem and other primitive parts of the brain, like the thalamus, wake up first. The neocortex, the part where all the complicated thinking goes on, wakes up later. Consciousness is not a simple state that is either on or off. 

There are distinctions that are not immediately obvious, such as the difference between being unresponsive and being unconscious. “Patients under general anesthesia can sometimes carry on a conversation using hand signals, but postoperatively, they deny ever being awake. Thus, retrospective oblivion is no proof of unconsciousness”, says Dr. Alkire. The standard measure of unconsciousness is that a subject or patient does not respond to commands. By that standard, when a subject responds, he’s conscious.