What is the difference in (brain) an operation when you get the anesthesia in your arm versus your neck?

Systemic vs .local: Anesthetic or sedative agents introduced into a vein (usually in the arm) are dispersed in the blood stream and affect the consciousness centers in the brain. Anesthetic agents used in the neck or spinal column produce 'regional' anesthesia (numbness only) and usually don't affect a persons state of consciousness.

General/regional: Not sure what your asking. We have only two ways of putting people to sleep, general anesthesia. Medicine into the blood through an intravenous or breath in medicine through the lungs. Both ways the medicine works in the brain to produce unconsciousness. We can numb one or more parts of the body by placing local anesthetics, 'novacaine' next to nerves. Like a spinal or a block.

Local vs general : Arm surgery can be done under nerve block. This does not affect your memory unless you get additional sedatin. Neck surgery does require one to under go general anesthesia which does affect brain more for first 24 hours.

Depends on Problem: Sometimes local anesthesia can be given right at the site of the surgery such as for carpal tunnel surgery. More extensive hand, arm, or shoulder surgery requires the numbing medicine to be delivered just before the nerves enter the arm. Any carefully placed numbing block should provide comfort and not affect your brain.

None: The medicate will hit your heart earlier if given by an IV in the neck versus the hand.