“What happens to your brain under general anesthesia?”

The brain gets put to sleep so the patient is unaware of the procedure.

This is too complicated to explain. But basically, the brain continues to function in deep sleep mode with some of the processes blunted significantly.

Boris Yaguda, M.D.

Ion channels in the membranes of brain cells are reversible blocked, causing unconsciousness, analgesia, and amnesia.

The answer is both very straightforward, both on a deeper level extremely complex. On the straightforward level, general anesthesia is a controlled unconsciousness. The patient becomes unaware of anything going on during the time of general anesthesia. but when you dive deeper than this rather superficial answer, the answer becomes very complex, and in fact, all the complete answer is probably not known even today. Certain systems within the brain remain functioning, while others are temporarily "shut down". Fortunately, with general anesthesia, the "shut down" of these systems is reversible, so that the patient regains consciousness the the completion of the anesthetic. You may have read if brain waves, and frequencies of various parts of the brain communicating with other parts of the brain...all of these systems are modified by the effects of administration of general anesthesia. in general, the frequencies of these communications occur at lower frequencies than normal. Additionally, the communications of various parts of the brain with other parts of the brain. and with other body systems are modified.
Fortunately, with administration of anesthesia medications in the hands of those who are properly trained to manage the administration of anesthesia, these effects are temporary and reversible, so that the patient regains consciousness at the completion of the anesthesia administration. But this takes years of study and training to become proficient at it.

You are under a controlled coma. You cannot breathe, move, or speak. You are without reflexes.