MA, Berlin School of Mind and Brain
Flatliners is an American science fiction horror movie directed by Niels Arden Oplev, released in September 2017. Medical student Courtney is obsessed with the idea of an afterlife, wanting to find out what happens to your brain after death. Together with her fellow students she comes up with a spectacular experiment: using defibrillation to stop the heart beat while recording brain activity in the scanner. Initially Courtney begins to recall memories of past events and experiences increased intelligence and euphoria. Suddenly, she can play the piano and answer all questions in class perfectly. Eventually, the other students all want to “flatline” and they decide to increase the time period from 60 seconds up to 3 minutes. It soon turns out that there are rather severe side effects, the students are haunted by visions of bad things they did in life. The movie turns into a quite shocking horror trip for the all-to eager medical students and in the end, they wish they never had experimented with death. Watching that movie, which is quite fascinating for the first 30 minutes but then turns into a crazy and all too familiar horror movie, made me think about what actually happens to the brain after we die and made me check scientific evidence. The movie got rather bad reviews from critics (justified as I would say), however it raises some interesting neuroscientific questions about what goes on in our brains after we die.
A paper in the journal on resuscitation from 2014 describes the near-death experience Mr. A had after cardiac arrest. Mr. A could exactly describe what happened while the doctors tried to reactivate his heart: “The next second, I was up there, looking down at me, the nurse and another man who had a bald head.” So far, it was assumed that when the heart stops beating and stops sending vital blood to a person’s brain, all awareness immediately ends. However, those patients that had an cardiac arrest and could be revived have often reported memories of the events. Doctors mostly dismissed such anecdotal evidence as hallucinations and researchers haven’t been too excited about research on near-death experiences either, mainly because it is viewed as something outside the reach of scientific exploration (ethical issues are the main objective). Sam Parnia from Stony Brook University in New York decided to investigate near-death experience and so he and his colleagues analysed more than 2,000 cardiac arrest events – moments when a patient’s heart stops and they are officially dead. Of the 101 patients that could be revived only 2 patients had experiences that were tied to external events, but 50 % reported experiences related to fear, seeing animals or plants, bright light, violence and persecution, deja-vu, seeing family members or calling events post-cardiac arrest. Heightened senses, a distorted perception of time passing and a feeling of disconnection from the body were also common sensations that survivors reported. Mental experiences ranged from terrifying to very pleasant. So far, no predictor has been discovered for why some patients are more likely to remember something from their death and why some people experience terrifying scenarios while others report very pleasant episodes. Memories can be distorted by the massive brain swelling that occurs following cardiac arrest, or by strong sedatives administered at the hospital. Even if people do not explicitly recall their near-death experience (NDE), it could still affect them on a subconscious level. This could explain why some patients adopt a more altruistic approach to life, whereas others develop Post traumatic stress disorder after NDE. Parnia and his colleagues are already planning on follow-up studies trying to address some of those questions: “Death should be treated as a scientific subject just like any other. We have the means and the technology. Now it’s time to do it.”
Researchers from University of Michigan investigated in 2013 brain activity immediately following cardiac arrest to address that question. They used electroencephalography in rats to analyze changes in frequency bands and could identify a transient burst of synchronous gamma oscillations that occurred within the first 30 seconds after cardiac arrest. Scientists distinguish four distinct stages of brain death. Cardiac arrest stage 1 (CAS1) reflects the time (~4 seconds) between the last regular heartbeat and the loss of oxygenated blood pulse (i.e. clinical death). The next stage (CAS2) lasts about 6 seconds, and ends with a burst in low-frequency brain waves (so-called ‘delta blip’). The third death stage, CAS3, lasts approximately 20 seconds at which point there is no more evidence of meaningful brain activity at the final stage, CAS4. In sum, these data suggest that long after clinical death, the brain enters a brief state of heightened activity that is normally associated with wakeful consciousness. The gamma oscillations during cardiac arrest were global and highly coherent. The authors even suggest that the level of activity observed during the final death stage (CAS3) not only resembles the waking state, but might even reflect a heightened state of consciousness. This could be a possible explanation for the “highly lucid and realer-than-real mental experiences reported by near-death survivors”. However, this claim depends on the quantification of ‘consciousness’. But how can we quantify ‘consciousness-related activity’? To date, there is no general agreement of a matrix of consciousness that we can use to infer the true state of awareness. And even if we could come up with such a consciousness index in humans, how could we relate it to the rodent experience? The obvious next step is to test weather similar patterns of brain activity are observed in humans after clinical death and show that such activity is highly correlated to near-death experience. Does the presence or absence of a certain activity predict whether or not a person reports a near death experience? This obviously faces technical and ethical challenges, but would provide important evidence to link the neural phenomena to the phenomenal experience.
When the curtain is drawn, we really have no idea of what is going to happen. But we know sooner or later all of us will find out.
Originally published in the SCAN Berlin blog