What does this mean for the EEG’s ability to reflect consciousness? “The study does support the possibility that certain EEG features might not always accurately capture the level of consciousness in surgical patients,” says senior author George A. Mashour, M.D., Ph.D., chair of the U-M Department of Anesthesiology.
However, “EEG likely does have value in helping us understand if patients are unconscious. For example, a suppressed EEG would suggest a very high probability of unconsciousness during general anesthesia. However, using high anesthetic doses to suppress the EEG might have other consequences, like low blood pressure, that we want to avoid. So, we will have to continue to be judicious in assessing the many indices available, including pharmacologic dosing guidelines, brain activity, and cardiovascular activity.”
Pal notes that there is physiological precedent for an EEG mismatching behavior; for example, the brain of someone in REM sleep is almost identical to an awake brain. “No monitor is perfect, but the current monitors we use for the brain are good and do their job most of the time. However, our data suggest there are exceptions.”
Their study raises intriguing questions about how consciousness is reflected in the brain, says Pal. “These measures do have value and we have to do more studies. Maybe they are associated with awareness and what we call the content of consciousness. With rats, we don’t know-we can’t ask them.” (1)
Close your eyes.
And you will dream.
Do you see?
It is not the activity of the brain that tells us that the brain is active.
But its ability to stay inactive.
You cannot be awake when you are awake.
But only when you are sleeping…
The kid is still in bed…