Brain activity may continue for more than 10 minutes after the body appears to have died, according to a new study.
Canadian doctors in an intensive care unit appear to have observed a person's brain continuing to work even after they were declared clinically dead.
In the case under study, doctors confirmed their patient was dead through a range of the normal observations, including the absence of a pulse and unreactive pupils. But tests showed that the patients' brain appeared to keep working – experiencing the same kind of brain waves that are seen during deep sleep.
In the study that noted its findings could lead to new medical and ethical challenges, doctors reported that they had seen ''single delta wave bursts persisted following the cessation of both the cardiac rhythm and arterial blood pressure (ABP)''. The findings are reported in a new study published by a team from the University of Western Ontario.
Only one of the four people studied exhibited the long-lasting and mysterious brain activity, with activity in most patients dying off before their heart stopped beating. But all of their brains behaved different in the minutes after they died – adding further mystery to what happens to them after death.
The doctors don't know what the purpose of the activity might be, and caution against drawing too many conclusions from such a small sample. But they write that it is difficult to think the activity was the result of a mistake, given that all of the equipment appeared to be working fine.
Researchers had previously thought that almost all brain activity ended in one huge mysterious surge about a minute after death. But those studies were based on rats – and the research found no comparable effect in humans.
''We did not observe a delta wave within 1 minute following cardiac arrest in any of our four patients,'' they write in the new study.
What happens to the body and mind after death remains almost entirely mysterious to scientists. Two other studies last year, for instance, demonstrated that genes appeared to continue functioning – and even function more energetically – in the days after people die.