Isn't it crazy with one prick of anesthetics you can be out and then awaken hours later and have no recollection of what just happened? Sleep is like this too except, you have to close your eyes for a little then all sudden "poof", you awake to a morning sun. Sleep and anesthesia seem to be one in the same, but in reality they are not. Researchers in Canada measured the long field potentiation and coherence of cortical neurons in anesthetize and sleeping cats to investigate the differences.
Slow wave sleep (SWS) or what we call sleep is characterized by sleep slow oscillations, a characteristic of anesthesia. These oscillations form by cortical cells alternating between depolarizing and hyperpolarizing states. Depending on these oscillations neurons can either be active, a state of high synaptic activity or a silent state, low synaptic activity. Both aestheticize cats and sleeping cats were found in silent states but the amount of time aestheticizes cats were in the silent state differed.
Cats in SWS were found to have irregular slow waves or slow oscillations within each of the recorded cortical regions. When the anesthesia Ketamine- xylazine was injected into the cats, these regions showed consistent slow oscillations. These findings concluded that during SWS not all the brain regions are in silent states or inactive, so in sense, the brain still can processes information from the outside world. Opposite of that, aestheticize cats cannot process information because most the brain regions are in an inactive phase. So when a person receives anesthetics for surgery, they are not able to process that surgeons are cutting open their bodies, compared to a person who is able to wake up in the middle of the night because he or she processed that there might be a fire outside.
With the use of three different frequencies, regions of the brain could were investigated whether there are synchronous or non synchronous activities in the brain during the SWS and anesthesia. Aestheticized cats were found to have synchronous frequencies in contrast to nonsynchronous activities in SWS cats. These findings explain why a person can recall some of their dreams when they wake up compared to a person waking up from receiving an anesthetic. Because slow waves start to decrease as a person is about to wake up, there is a point in time where the active state is a little longer than a second, allowing a person to somewhat recall their dreams. While when someone is under anesthesia, the time in silent state is double compared to SWS. Synchronous brain activity allows for not time for regions of the brain to become consciousness during the transition from silent to an active state.
With these finding it hoped that further investigation of consciousness and unconsciousness could be understood. With many patients under comas for many days, months, and years, wouldn't it be a miracle if there was a way to wake them up?
Chauvette, Sylvain, Crochet, Sylvain, Tinofeev, Igor, Volgushev, Maxim. "Properties of Slow Oscillation during Slow- Wave Sleep and Anesthesia in Cats." The Journal of Neuroscience. 31 (2011)