This is a very sensitive subject so I had to pray & think hard about my response and I hope it helps this discussion.
Spiritually, that person is unconscious but still alive because they have the breath of life from God. Depending on the coma level they may still retain a level of awareness that allows them to respond or recall family visits, prayers and such and most importantly be stimulated back to consciousness at different points by human intervention.
People in comas can have recall and dreams because they're alive. Because of their loss of control, it's hard to say where exactly those visions may come from. But no one has a round-trip ticket between heaven and earth except Jesus. That is one of the points He was making in
John 3:13 KJV. He is the only one that can tell you about heaven.
I think the growing trend where comatose or anesthesized patients are being thought to have the 'supernatural powers' that dead people are claimed to have, with respect to knowledge of and visits to heaven adds further to the deception of the state of the dead. People are now claiming to have died and come back at will or stimulated back by the voices of their loved ones or their doctors. No human being dead or alive has that power or authority.
Like a coma patient, a dead person is also unconscious but the Bible says:
"
The dead know not anything...their love, and their hatred, and their envy, is now perished" (Ecc. 9:5,6). There is no "wisdom in the grave" (Ecc. 9:10)
The thread "Do you take the Bible literally?" from p3 has a lot more reference texts on why the dead are not conscious of anything and why they're not in heaven. It also references when they will be ALL raised from the dead and stimulated back to consciousness
by God- at the end of this earth.
http://www.longhaircareforum.com/showthread.php?t=613423&page=3