Has science explained life after death?

­As many as 18 percent of people brought back from death after a heart attack said they'd had a NDE [source: Time]. While many religious adherents might not be surprised by these extraordinary claims, the idea that human consciousness and the physical body exist distinctly from each other flies in the face of science. Someone with a dying brain should not be able to form new memories. So how can anything but a metaphysical explanation make sense of NDEs?

A study from the University of Kentucky has quickly gained ground among scientists as possibly the best explanation for NDEs. Researchers theorize that the mysterious phenomenon is really an instance of rapid eye movement (REM) intrusion. In this sleep disorder, a person's mind can wake up before his body, leading to a conscious experience of being detached from their mortal coil.

As such, the Kentucky researchers believe that these near death studies are merely moments of confusion as the brain enters a dream-like state. This theory helps explain how people can have mystical experiences, with sights and sounds, after the brain has died.

Basically, the area where REM intrusion is triggered is found in the brain stem , which can operate virtually independent from the higher brain. So even after the higher regions of the brain are dead, the brain stem can conceivably continue to function, and REM intrusion could still occur [source: BBC].

While the REM intrusion theory for near-death experiences explains the apparent hallucinations that accompany NDEs, it doesn't explain OBEs. How can a person watch their body after they've died? Though out-of-body experiences are sometimes reported as part of the near-death experience, they can also stand alone, indicating that they are a different animal than NDEs.

This is supported by a bit of accidental research. To find the cause of a 43-year-old epileptic patient's seizures, Swiss neurologist Dr. Olaf Blanke conducted a brain mapping test using electrodes planted on the brain to determine which area controls what function. As one region was being stimulated, the female patient had a sudden out-of-body experience. She told Blanke that she could see herself from above [source: New York Times].

Blanke determined that by electrically stimulating the woman's angular gyrus, a part of the temporal parietal junction, he could induce her OBEs. What's remarkable is that the patient experienced an OBE each time her angular gyrus was arbitrarily stimulated. Now, the job of the temporal parietal junction (TPJ) is to organize everyday stimuli into a coherent package. However, it's also the region that controls our comprehension of where our body exists in physical space.

Blanke believes that a misfiring of this region is responsible for OBEs. If any of the information being sorted by the temporal parietal junction becomes crossed, like where we are in space, then we could seemingly be released from the confines of our body -- even if only for a moment.

Both Blanke's and the University of Kentucky theories explain OBEs and NDEs. But can you put the two together in order to explain the recalled experiences of Pam Reynolds? These theories do not resolve how Pam Reynolds and others like her viewed themselves outside of their bodies while they were brain-dead.

NDEs may be a result of REM intrusion, triggered in the brain stem. But OBEs are controlled by a region of the higher brain, which is clinically dead when NDEs occur. What's more, it seems logical to believe that the higher brain must still function in order to interpret the sensations produced by the REM intrusion triggered in the brain stem.

Even though combining the theories put forward by the University of Kentucky and Blanke does not explain peoples' visions of heaven, god, or an afterlife, it does not mean that either theory is wrong. If neurology does come up with the definitive explanation for NDEs, and science can explain the "how," will it also reveal the "why"? Discovering an explanation for NDEs may open a door to the metaphysical world, changing the way we understand our physical bodies, life, and even the soul.

As physician Dr. Melvin Morse wrote, "Simply because religious experiences are brain-based does not automatically lessen or demean their spiritual significance. Indeed, the findings of neurological substrates to religious experiences can be argued to provide evidence for their objective reality" [source: Morse].