If you own a tv, radio, or computer, you’ve probably heard about the recent neuroscience experiment that studied after-death brain activity in rats. Perhaps you’ve seen it under titles like: Near-death experiences are ‘electrical surge in dying brain’ or Near-death experiences exposed: Surge of brain activity after the heart stops may trigger paranormal visions. You may have heard some jargon about brainwaves and frequency coupling or some such. What does it mean? It is time to chuck your rosary, or at least your copy of Proof of Heaven? (The answer to the latter, in case you’re wondering, is yes.)
The article that caused such a stir was penned by researchers at the University of Michigan and published in the scientific journal PNAS. The experiment was simple and so obvious that I immediately wondered why no one had done it before. The scientists implanted six electrodes in the surface of the rat’s brain. They recorded from the electrodes while the rat was awake and then anesthetized. Finally, they injected a solution into the rat’s heart to make it stop beating and recorded in activity in the rat’s brain while it died. None of these steps are unique. Neuroscientists often place electrodes in the brains of living rats and certainly lab rats are anesthetized and sacrificed on a daily basis. The crucial change that these scientists made was recording after the animal’s death.
What happened once its heart stopped? A lot, probably more than anyone would have expected. In the first 30 seconds, the researchers observed rapid and coordinated neural activity in the rat’s brain. Unlike under anesthesia, when the rat’s brain was quieter than its wakeful norm, the dying brain was as active and, by some measures, more active than it was when fully awake and alive. We’re not talking about zombie rats here – this activity faded and disappeared beyond the 30-second window after cardiac arrest. Still, something dramatic and consistent happened in those dying moments. The brain activity was essentially the same across all nine rats that died from cardiac arrest and eight other rats that the scientists sacrificed using carbon dioxide inhalation. The results were no fluke.
Of course, these findings (and the headlines touting them in the news) beg the question: is this activity the neural basis for near-death experiences? The answer, of course, is we don’t know. We obviously can’t ask the rats what they experienced, if they experienced anything at all. Still, the activity during the 30-second window wasn’t drastically different from the brain’s wakeful activity, at least according to some of their measures. It’s certainly possible, maybe even probable, that the rat experienced something during this time. That fact alone is intriguing. To say more, we’ll need more grants, more studies, and more dead rats.
For the time being, I’m sure people will spin these results according to their pre-existing beliefs. Some will probably say that the brain activity at death is the physiological echo of God coaxing the soul from the body. And who am I say it ain’t so? But there are certainly other explanations. Neural rhythms arise naturally from the wiring of the brain. Neurons form an incredible number of circuits, or wiring loops, that reverberate. Each neuron is a complex little creature in its own right: electrically charged, tiny, tentacled, and bustling with messenger molecules, neurotransmitters, and ions. When neurons are deprived of oxygen and energy, their electrical charges change drastically, which can cause them to fire errant signals at each other. Without input from the outside world, these errant signals may harmonize in ways that reflect the internal wiring of the system. It’s a little like playing a trumpet. When you blow into the trumpet, your breath is a chaotic rush of air, yet it emerges as a clear and orderly tone. An organized system can make order out of chaos. The same might be said of your brain. And if it turns out that this type of coordinated brain activity actually does cause a special experience when you die, consider it an accidental symphony that plays you one last song before you go.
Photo credit: Paul Stocker on Flickr, used via Creative Commons license
Borjigin J, Lee U, Liu T, Pal D, Huff S, Klarr D, Sloboda J, Hernandez J, Wang MM, & Mashour GA (2013). Surge of neurophysiological coherence and connectivity in the dying brain. Proceedings of the National Academy of Sciences of the United States of America PMID: 23940340