Can neuroscience shed light on one of life's biggest mysteries - death? In a new study just published in PNAS, researchers observed a surge of brain activity just moments before death. This raises the fascinating possibility that they have identified the neural basis for near death experiences.

First, to put this research into context, death-related brain activity was examined in rats, not humans. For obvious reasons, it is easier to study the death process in animals rather than humans. In this study, nine rats were implanted with electrodes in various brain regions, anaesthetised then 'euthanized' (i.e., killed). The exact moment of death was identified as the last regular heartbeat (clinical death). Electroencephalogram (EEG) was recorded during normal waking phase, anaesthesia and after cardiac arrest (i.e., after death) from right and left frontal (RF/LF), parietal (RP/LP) and occipital (RO/LO) cortex. The raw EEG (i.e., ‘brain waves') for each area is shown in the Figure below. On top (Panel A), the recording ranges from about 1hr before death to 30mins afterwards. At this coarse time scale you can basically see a sudden decrease in brain activity after cardiac arrest - everything seems to flatline at the moment of death. However, if we now zoom in on the moment just after death (Panels B and C below), we can see that the death process actually involves a sequence of structured stages, including a surge of high-frequency brain activity that is normally associated with wakefulness and conscious awareness.

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