What Happens When You Die? (VIDEO)

Hi everybody. Cara Santa Maria here. Perhaps you're one of the eight million Americans who claim to have had a near-death experience. Did you see a bright white light at the end of a tunnel? Maybe you floated above yourself in an out-of-body experience. Overwhelmingly, people who've had so-called near-death symptoms report a calmness, lack of fear, and feeling of being one with the universe.

A relatively simple explanation of the near-death experience requires little scientific reasoning and absolutely no measurable evidence. If someone is on death's door and then suddenly pulled back into the realm of the living, perhaps he or she glimpsed into the moments prior to the soul leaving the body and joining the great cosmic consciousness beyond. This ghost-in-the-shell hypothesis, if you could call it that, is ubiquitous and seems to satisfy the imaginations of the public at large. In fact, 71% of Americans believe in the persistence of the soul after death. And in 1907, Massachusetts physician Duncan MacDougall claims to have measured the mass of the soul as it exited the body upon its passing--21 grams, to be exact.

Granted, nobody has ever managed to reproduce MacDougall's findings, and there exists not a single shred of physical evidence as to the existence of the, lets face it, fundamentally unmeasurable soul. So, scientists have set out to find an evidence-based explanation for near-death phenomena.

First of all, I think it's interesting to note that the vast majority of near-death survivors never actually report having a near-death experience. And in one study, around half of the people who reported one were not actually in danger of dying. What's clear is that when the brain undergoes severe trauma, like reduced oxygen flow, blood pressure drops, or sharp increases in blood carbon dioxide levels, interesting things start to happen psychologically.

First, a white light at the end of a tunnel, as David Hovda, of the UCLA Brain Injury Research Center explains, is the only thing we can really expect a person to see as they get closer and closer to death. For efficiency's sake, the brain tends to function only in areas needed for basic survival, like the hindbrain, which includes the pons and medulla. Given that the rest of the higher brain regions are essentially shut down, if visual areas like the superior colliculus or occipital cortex are suddenly activated, no higher-level processing can exist, and a bright light is all we would be able to see.

And in 2005, researchers in Switzerland found that the so-called out-of-body experience so commonly reported in near-death cases can be induced by stimulating the temporo-parietal junction on the right side of the brain. This research offers compelling evidence that disruption of the very brain region thought to be responsible for sensory integration and the so-called sixth sense of proprioception--or understanding where your body is in space--could produce a sensation like we're floating above our own bodies. And anyone who has abused the drugs ketamine or dextromethorphan understands what a dissociative anesthetic can do. These drugs act on NMDA receptors in the brain and can produce a sensation that you're detached from your own body or even from the world. Knowing that out-of-body experiences can be induced both during neurosurgery and recreational drug use provides clues that such experiences likely have a neurological basis.

And in my opinion, one of the most fascinating, yet highly controversial explanations of near-death phenomena comes from Dr. Rick Strassman, who, in the 1990s, proposed that dimethyltryptamine, or DMT, is actually found within the human brain and released in large quantities from the pineal gland during death's approach (and perhaps during birth, as well). DMT is a naturally occurring psychedelic, and it's been dubbed the spirit molecule for its intense psychotropic properties. So, if Strassman's research pans out, it could be the case that the near-death experience is little more than a really good trip.

What do you think? You can reach out me on Twitter, Facebook, or leave your comments right here on The Huffington Post. Come on, talk nerdy to me!

See all Talk Nerdy to Me posts.
Like Cara Santa Maria on Facebook.
Follow Cara Santa Maria on Twitter.

testPromoTitleReplace testPromoDekReplace Join HuffPost Today! No thanks.