Brain Activity in the Final Moments of Life: New Study Decodes Gamma Wave Surges in the Dying

Wednesday - May 3 2023, 20:09 UTC - 1 year ago

A new study published in the Proceedings of the National Academy of Science has revealed that two of four comatose dying patients experienced a potential surge in gamma waves at the point of death, implying the possibility of near-death experiences.

Is our life replayed in front of our eyes as we die? What activates the brain in the final moments of life? These questions are a long-standing neuroscientific paradox.

Survivors of near-death experiences commonly recall extraordinary moments passing in a flash of seconds — from some experiencing bright lights at the end of a tunnel to others saying their precious life moments replayed in an instant, and some witness floating outside their bodies.

However, it is unclear what causes these brief flashes of light in the final moments of life. Now, a new study has attempted to decode the brain activity that leads to these experiences during death.

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The University of Michigan team discovered signs of a rapid surge in brain waves that could be linked to sudden consciousness in the final moments of a person's life. The team studied four dying patients in intensive care after their life support was turned off due to ineffective treatment. The researchers examined the second-by-second records of these patients as they were being monitored with an electroencephalogram (EEG).

They discovered that two patients experienced a spike in brain waves in the gamma frequency, which is known to be the fastest brainwave and mainly occurs when an individual is conscious. Both of these patients (24 and 77 years old) were women.

This increase in brain activity near the point of death was detected in the "posterior cortical hot zone." This area of the brain is critical for conscious processing. When this part of the brain activates, it means the person can hear, see, and feel things. Reportedly, this region is also associated with dreaming, visual hallucinations in epilepsy, and changes in consciousness.

The team does not know why only two patients experienced a surge in brain activity while the other two did not. Furthermore, it is impossible to determine whether the surge was related to possible visions in the final moments.

The team hopes to collect more data in order better to understand brain activity in the final moments of life.

The results have been published in the journal Proceedings of the National Academy of Science (PNAS).Study abstract: .

The brain is assumed to be hypoactive during cardiac arrest. However, animal models of cardiac and respiratory arrest demonstrate a surge of gamma oscillations and functional connectivity. To investigate whether these preclinical findings translate to humans, we analyzed electroencephalogram and electrocardiogram signals in four comatose dying patients before and after the withdrawal of ventilatory support. Two of the four patients exhibited a rapid and marked surge of gamma power, surge of cross-frequency coupling of gamma waves with slower oscillations, and increased interhemispheric functional and directed connectivity in gamma bands. High-frequency oscillations paralleled the activation of beta/gamma cross-frequency coupling within the somatosensory cortices. Importantly, both patients displayed surges of functional and directed connectivity at multiple frequency bands within the posterior cortical "hot zone," a region postulated to be critical for conscious processing. This gamma activity was stimulated by global hypoxia and surged further as cardiac conditions deteriorated in the moments before death. Our results point to preclinical observations on surge of gamma activity as a possible neural correlate of the near-death experience in humans.