Uncanny synchronicity in the brain during near death experiences and meditation

People who have had a near-death experience commonly report a sense of wellbeing and peace, detachment from the world, the feeling of being outside their own body, and seeing a bright light. People who meditate deeply often report very similar sensations. Research reported yesterday in the journal PNAS suggests what may link the two experiences.

The scientists induced heart attacks in rats while they recorded the electrical activity in their brains using electroencephalography (EEG). To their surprise, they found a surge of activity in the rats’ brains before death. Specifically, there was an increased “coherence” or synchrony in a particular frequency band known as gamma waves. “High-frequency neurophysiological activity in the near-death state exceeded levels found during the conscious waking state,” say the researchers.

In 2004, a study that compared the brain activity of Tibetan monks as they meditated with that of novice meditators found that the monks had the ability to induce “high-amplitude gamma synchrony” in their own brains.

Gamma wave synchrony may be associated with consciousness and awareness, so what we may be seeing in the brains of both meditators and people near to death is a state of heightened consciousness. Meditators induce this state by focusing their attention and silencing the constant chatter of the brain. In people nearing death a very similar suspension of the usual thinking processes may be imposed on the brain, perhaps by a lack of oxygen.

According to the psychologist Chris Chambers, blogging yesterday in the Guardian, we should be cautious about over-interpreting the results:

The first problem is that we don’t know whether rats experience consciousness in the same way we do – or at all – so we don’t know what this activity profile means. Second, even if rats are conscious, we can’t conclude from their brain activity alone that these bursts of activity reflect consciousness. To do so would be to assume that gamma activity is exclusively associated with consciousness (it isn’t), and to fall prey to a logical fallacy known as reverse inference. Borjigin and colleagues are careful to avoid this trap – at no point in their paper do they argue that their rats experienced NDEs [near-death experiences].

As ever, science doesn’t provide instant explanations for anything. It merely throws up fascinating correlations that deserve further investigation. The next step, says Chambers, will be to record the brain activity of human volunteers as they die.

We have a much better idea of what happens in the brains of people when they meditate, thanks to brain scanning and EEG studies such as the one mentioned above. Interestingly, highly experienced meditators don’t appear to have any trouble maintaining the meditative state as they pass away. The Buddha himself is said to have meditated as he died. And in his book The Universe in a Single Atom, the Dalai Lama describes a state of consciousness known in the Tibetan tradition as the “clear light state”, which is an experience shared by people near death and meditators:

This is a state of consciousness understood to be extremely subtle that manifests briefly in all human beings at the moment of death. Very brief similitudes of this state may occur naturally at other times, such as during sneezing, fainting, deep sleep and sexual climax. The principal characteristic of the state is a total spontaneity, the absence of self-consciousness or self-grasping. In an experienced practitioner, this state can be deliberately induced through meditative techniques, and when it naturally occurs at death such an individual can sustain the state while maintaining mindfulness for a long period.

His Holiness goes on to claim that he has known monks to enter into a state of suspended animation at death by maintaining this clear light state. Even though they were clinically dead, he says, they remained upright in the meditation posture for several days, their bodies failing to decompose despite the tropical heat.

Of course, they probably weren’t dead at all, but the fact their brain was able to maintain this state while the rest of their body was failing is indeed fascinating.