Is there life after death for our brains? It depends.

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Loretta Norton, a doctoral student at Western University in Canada, was curious, so she and her collaborators asked critically ill patients and their families if they could record brain activity in the half hours before and after life support was removed. They ended up recording four patients with electroencephalography, better known as EEG, which uses small electrodes attached to a person’s head to measure electrical activity in the brain.

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In three patients, the EEG showed brain activity stopping up to 10 minutes before the person’s heart stopped beating. But in a fourth, the EEG picked up so-called delta wave bursts up to 10 minutes after the person’s heart stopped. Delta waves are associated with deep sleep, also known as slow-wave sleep. In living people, neuroscientists consider slow-wave sleep to be a key process in consolidating memories.

The study also raises questions about the exact moment when death occurs. Here’s Neuroskeptic :

Another interesting finding was that the actual moment at which the heart stopped was not associated with any abrupt change in the EEG. The authors found no evidence of the large “delta blip” (the so-called “ death wave “), an electrical phenomena which has been observed in rats following decapitation.

With only four patients, it’s difficult to draw any sort of broad conclusion from this study. But it does suggest that death may be a gradual process as opposed to a distinct moment in time.