2023-05-03 16:19:44
Accounts of near-death experiences — white light, visits from deceased loved ones, voices, etc. — capture our imagination and are deeply embedded in our cultural landscape. Is it possible that the human brain is activated by the process of death? Recently, researchers have reported increased electrical activity in the brains of dying people. It might be associated with last-minute conscious experiences, a new vision of the role played by the brain in this final stage of life.
Brain function at the time of death is poorly understood. Although overt loss of consciousness is invariably associated with it, it is unclear whether it is possible for patients to possess some kind of hidden consciousness during the dying process, such as in near-death experiences (NDEs). .
The latter, reported as very lucid, “more real than real” and common to people from diverse cultural and religious backgrounds, have been described by 10-20% of cardiac arrest survivors. NDEs represent a biological paradox that challenges our fundamental understanding of the dying brain, widely believed to be nonfunctional under such conditions. Indeed, it has been claimed that these episodes occur during clinical death even during electroencephalogram (EEG) electrical quiescence.
The fact that these reports share so many common elements begs the question of whether there is something fundamentally real underlying them — and that those who managed to survive death provide insight into a consciousness which does not go away completely, even following the heart stops beating.
Researchers from the University of Michigan have provided early evidence of increased brain activity, correlated with consciousness in the dying brain. Their study is published in the journal Proceedings of the National Academy of
Science.
A cerebral burst before a complete stop
The study, led by Jimo Borjigin, associate professor in the Department of Molecular and Integrative Physiology and the Department of Neurology, and his team, follows animal studies conducted nearly 10 years ago in collaboration with George Mashour, founding director from the Michigan Center for Consciousness Science.
Indeed, animal models of cardiac and respiratory arrest have demonstrated increased gamma oscillations and functional connectivity. To determine whether these preclinical findings translate to humans, the authors analyzed EEG and EKG signals from dying people, before and following ventilatory support was removed.
Specifically, the team identified four patients who died of cardiac arrest in hospital while under EEG monitoring. All four patients were in a coma and unresponsive. The medical decision to disconnect them from life support with their families’ permission was finally made.
Upon removal of life support, two of the patients showed an increase in heart rate as well as an increase in gamma wave activity, believed to be the most rapid brain activity associated with consciousness.
Additionally, activity was detected in the so-called hot zone of the neural correlates of consciousness in the brain, the junction between the temporal, parietal and occipital lobes at the back of the brain. This area has been correlated in the healthy human brain to wakefulness and dreaming, but also to visual hallucinations in epilepsy and altered states of consciousness in other brain studies.
These two patients had previously reported seizures, but none of the seizures had occurred in the hour before their deaths, says Nusha Mihaylova, who has been collaborating with Borjigin since 2015 collecting EEG data from deceased patients undergoing treatment in the care unit. intensive. The other two patients did not show the same increase in heart rate upon removal of life support nor increased gamma activity.
Nevertheless, according to the authors, it seems that the gamma activity of the first two patients was stimulated by global hypoxia (lack of oxygen supply to the body’s tissues) and increased further as the conditions heart conditions deteriorated in dying patients. These data demonstrate that the surge in power and gamma connectivity observed in animal models of cardiac arrest can therefore also be observed in some patients during the dying process.
George Mashour explains in a
communiqué : « How living experience can emerge from a dysfunctional brain during the dying process is a neuroscientific paradox. Dr. Borjigin conducted an important study that helps shed light on the neurophysiological mechanisms underlying ».
The beginnings of a “secret” consciousness still misunderstood
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Due to the small sample size, the authors caution once morest making overarching statements regarding the implications of the results. They also note that it is impossible to know in this study what the patients experienced (because they did not survive to testify).
Larger studies, including EEG-monitored intensive care patients who survive cardiac arrest, might provide much-needed data to determine whether these bursts of gamma activity are evidence of hidden consciousness, even when approaching the death.
Although the mechanisms and physiological significance of these findings remain to be explored, these data demonstrate that the dying brain may still be active. They also suggest the need to reassess the role of the brain during cardiac arrest. This study then lays the groundwork for further research into covert consciousness during cardiac arrest, which might serve as a model system to explore the mechanisms of human consciousness.
Source : Proceedings of the National Academy of
Science
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#Surges #brain #activity #detected #dying #people
