Researchers at the University of Michigan have found that people experience a spike in gamma wave activity in the area of the brain responsible for consciousness, dreams and hallucinations just before death.
They believe these hallucinations are responsible for reports of people seeing bright lights, hearing voices or singing, or even seeing their loved ones as they approach death.
The study is still in its infancy – it only included four patients – but scientists hope it will pave the way for a better understanding of how the brain responds to death.
The researchers, whose results are published in PNAS, studied four patients who died after cardiac arrest while monitoring an electroencephalogram (EEG), a test that measures electrical activity in the brain using electrodes attached to the scalp.
These devices detect and record small electrical signals from the brain. Four patients included in the study were comatose and unresponsive.
Eventually it was determined that they were not receiving medical care, and with the permission of their families, they were taken off life support.
When the ventilator that was keeping them alive was removed, two patients experienced an increase in heart rate along with increased gamma wave activity.
Gamma wave activity is fastest in the brain and is associated with consciousness. Elevated gamma levels are usually associated with intense thinking and increased attention.
Previous research has shown that people with schizophrenia often experience high gamma waves in their brains.
High levels of gamma waves are also recorded when a person has an epileptic seizure.
All participants in the study who experienced high gamma activity before death had seizures throughout their lives, but not an hour before death.
It is also associated with psychosis and some harmful brain activity such as delusions and hallucinations.
The other two patients had neither the same increase in heart rate nor increase in brain activity.
The study follows an animal study conducted nearly a decade ago.
Similar gamma activation signals have been recorded in the brains of animals and humans during oxygen loss after cardiac arrest.
Because the sample size was small, the team cautions against making any global claims about the implications of the results.
They also note that it is impossible to know what the patients suffered because they did not survive.
Co-author Dr. George Mashor, founding director of the Michigan Center for the Science of Consciousness, said: “How vivid experiences can emerge from a dysfunctional brain during the dying process is a neuroscience paradox. Dr. Borjigin has done important research that helps shed light on underlying neurophysiological mechanisms.”
Lead author, Professor Jimo Borjigin of the University of Michigan, said: “We cannot establish a link between the observed neural signatures of consciousness and similar experiences in the same patients in this study. basis for our understanding of the hidden consciousness of dying people.
Larger studies may provide much-needed data to determine whether these bursts of gamma activity are evidence of subtle awareness even at death.
Source: Daily Mail
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