Consciousness is clearly linked directly to the brain in some way. When you feel a physical sensation, such as a sudden pain from a needle prick, the neural signal is sent to the brain, where it is processed and interpreted. This “interpretation” that the brain produces is somehow delivered to the conscious observer. Moreover, the conscious observer appears to be able to control various functions of the brain, the limit to which is unknown. The observer can seemingly interact with the brain and is linked in some capacity to what goes on in the brain. This is not necessarily true, however. It may be the case that all brain functioning is independent of the observer, and possibly deterministic. The observer may not be aware that it is not in control of choices, but merely experiences the mechanical processes of thought. After all, what would a person experience if their thoughts were controlled externally? Would they experience the thoughts induced onto them as genuine, as self-induced? How would they know the difference between brain functioning that was the result of their own compulsion or someone else’s compulsion?
Part of the observer’s interaction with the brain is, of course, through memory. Memory cannot be said to be stored entirely in the brain. However, we know that some memory is stored in the brain, and for the sake of discussion we will have to limit ourselves to the simplest scenario and operate under the assumption that all relevant memory is stored in the brain. The memories that an observer experiences are the result of the observer’s interaction with the physical structures (neural pathways) that make up a memory.
One could propose a test of consciousness to see whether it is capable of being independent of brain function. One could cryogenically freeze a living human being for 10 days, during which no brain activity whatsoever would occur. In other words, all cells of the body would be dead in every sense. After 10 days the person would be unfrozen and returned to life in a body that has not changed whatsoever (it doesn’t matter whether we have the technology to do this, it is nevertheless philosophically feasible). In other words, the body is instantaneously frozen in time for a period of ten days then returned to normal. We could then ask this person if they had any memories more recent than the instant they were frozen. If the response was positive, that would certainly allow for (but not prove) the existence of consciousness separate from bodily function. However, it needs to be understood that if the response is negative, this does not disprove anything in any way. As I have stated above, memories are physical, and therefore it would be seemingly impossible for new memories to be created while dead. Conscious experience may continue after death, but memory production will cease. Therefore it is reasonable to expect that no one who is revived from death will ever have any memories of the experience of being dead. If they did have memories, this would not necessarily prove that consciousness can exist outside of the physical. There are other ways that consciousness could be physically bound and that memories could form. Consciousness could be tied to cell structure, to matter, to energy, to anything. Along that same line of thinking, even if either the experience of consciousness were physical or the matrix of consciousness were physical, death would not necessarily be an end to consciousness.