We know the brain is needed for thinking, emotions, and memory so when the body dies and the soul moves to an eternal afterlife what would be its characteristics?
This isn't true, strictly speaking. We know that the brain is involved in thought processes, as well as emotional experiences, which appear causal. Memory too. However, what is unclear, either way, is whether the brain is the only active agent in these processes. I submit that it is not. Since the hypothesis is that there is a soul, I won't go into the question of its existence, but I will say a little about it.
There is a distinction to be made between soul and spirit, as the Visitor indicated. The distinction being that a soul might be said merely to be the life-force of a body, while the spirit is intelligent, free in will and emotional (there are connotations which I bring with this word that perhaps you do not... but I don't think it's important to talk about that right now). However, for the sake of simplicity, I will talk about the human soul as a spiritual soul, eliminating the need to make a separation.
Thus, to talk about the human soul is both to talk about something which gives life to it, but which is also intelligent, free in will, and emotional. So, to the question of whether the brain is
necessary for thought, or emotion, or memory, as I have said, I submit that this isn't the case. Rather, it is merely involved, in more ways than one.
Primarily it is the processing center of the information that it receives from the senses of the body. It processes this information, and the information processed is understood by the soul. It is difficult to talk about the soul in the human person, because the human body and the human soul are one, they are a union. Thus, you cannot point to a place on a person and say "there is the soul" and you cannot point to any part on a person's body and say "that is just body, nothing more." If, as I have stated, the human soul (which is spiritual) is the life-force of the body, then we might refer to the electrical impulses which interact in the brain, the
energy as being the person's soul. That might be a stretch, I'm not fully sure.
It is the soul wherein consciousness lies, for the human soul is intelligent. From this intelligence proceeds free choice and will, which causes action in the body. In death, the soul is displaced from the body. If the soul is the life-force of the body, the energy, then we might say that it is the energy which is displaced from the dead body.
It would have no memory and hence no identity.
This may be true, but I'm not sure about it yet. The reason I say this is because God is also spiritual, who is intelligent, and who seems to have memory and identity. I don't think I'm out of place by bringing God into the discussion since the hypothesis involves an afterlife. I simply assume we're talking about a Judeo-Christian perspective.
In any case, there is a rift that people don't usually talk about. If we're considering the Judeo-Christian perspective, then we have to include the belief in the Resurrection of the Dead at the end of time. If this is the case, then the answer to your question seems clear. For, if there is a resurrection of the body in the end, then what the soul does in heaven or hell would not be much different than what it does now, since it would once again be united with its body, and brain.
However, the rift which I mentioned is this, and I think it pertains more to your question: what happens to the soul between the death of its body and the resurrection of its body? Well, to answer this question, we might need to hash out another one: Is purgatory real? I suppose we could skip this question, as it is certainly possible to do so with the consideration of Saints, who enter into heaven directly after death.
As I write that last sentence, I realize there are things which still need to be made clear, for, why would there be a difference between a saint going directly to heaven after death and any normal person? The answer to this question lies in the meaning of the word "eternal." The term is a contrary to temporal. Temporal is that which operates by time. Some people might say that the temporal is that which is impermanent. This may be so, but that is only because anything that operates by time operates by change, and change implies impermanence. So, what is temporal is in a constant state of change, and this has to do with motion (and I don't simply mean spacial movement), for whatever is in motion is changing, and whatever is unmoving is also unchanging. However, what is unmoving, though it may not be said to be temporal, may also not be said to be eternal.
The eternal is also unchanging, but it is not unmoving. Rather, it's movement is infinitely fast. So, while the temporal is a sequenced reality, change flowing coherently and fluidly from change into change, the eternal is all change occurring simultaneously, thus being itself unchanging. For, all is at once. It is the infinite, truly holistic.
So, going back to the query of the soul. If every soul directly enters into eternity after death, then they immediately experience the resurrection of their bodies, and there is little more to discuss.
However, if there is a purgatory between death and resurrection, then there is more to discuss. Then the question becomes, what happens to the soul in purgatory, between death and the resurrection? If this weren't an issue, then neither would your questions of a soul's capacity for thought, memory and emotion after it's been separated from it's body. Because, if the soul immediately enters into eternity after death, then it is immediately reunited to its body in the resurrection and the question becomes irrelevant.
However, if there is a purgatory, a time after death whereby the soul is purged of its sinful inclinations and imperfections, then there is a time (whether great or small) that the soul spends displaced from the body. The question is, what can we say about such a soul?
If the time in purgatory is a time spent in purgation, cleansing, then what is the cleansing agent? Is it external or internal? That is, is something, perhaps God, purging the soul, or is the soul itself the active agent? If the purgation is by an external agent, then, once again, your question seems to be answered. The soul, mindless, emotionless, or not, once purged enters into the eternal, and experiences the resurrection, once again united to its body, full again with memories and emotion and mind that it always was.
But what if it is an internal change which must take place in purgatory? Well, if this is the case, then it would seem your answer is once again put to meaninglessness. For, if the change must needs be internal, then the soul must, by necessity, be a conscious, intelligent, freely willing, emotional entity. Otherwise, no change would take place, and there would be a drifting, mindless soul forever lost to meaninglessness (or until the day of resurrection). Naturally, this would render the state of purgation meaningless as no change would be effected in the soul whatsoever.
So, I think what it really boils down to is whether you want to posit a resurrection or not. If you want to eliminate the resurrection, then I would say that the soul would be forever incomplete, imperfect, and in eternal suffering, being disconnected from the body of which is is naturally in union.
