A study is based on a rare recording of a dying brain, which occurred accidentally at a Canadian hospital, suggests that there may be a final feeling of serenity as humans pass away.
Brain activity similar to meditation, dreaming or memory recall, passes over the brain in its final moments, the study found, possibly shedding light on what happens in our bodies in the moments before and after we die, write the researchers.
“Something we may learn from this research is: although our loved ones have their eyes closed and are ready to leave us, their brains may be replaying some of the nicest moments they experienced in their lives,” said Dr Ajmal Zemmar, the studyʼs co-author.
An 87-year-old man was admitted to a Vancouver facility after a fall, with neuroscientists hooking him up to electroencephalography (EEG) technology to detect seizures. EEG involves electrodes being placed along a patientʼs scalp in a bid to measure activity in different parts of the brain.
While the manʼs brain was being recorded with EEG, he suffered a heart attack and died, allowing scientists to examine what happened to the organ in the moments before and after his death.
“We measured 900 seconds of brain activity around the time of death,” said Zemmar, then based in Vancouver but now a neurosurgeon at the University of Louisville, US.
“We set a specific focus to investigate what happened in the 30 seconds before and after the heart stopped beating.”
A study of the EEG recording reveals that there was an increase in gamma oscillations, also known as “brain waves”, in the final seconds before the man died. Gamma oscillations are involved in high-cognitive functions, such as dreaming and information processing involving extreme concentration.
The oscillations are also associated with memory retrieval and flashbacks – supporting the idea that “your life flashes before your eyes” in the moments before death, Zemmar writes. “Through generating oscillations involved in memory retrieval, the brain might be playing a last recall of important life events just before we die, similar to the ones reported in near-death experiences.”
The increase in gamma oscillations was coupled with a reduction in delta, theta, alpha and beta waves, with researchers claiming “an intricate interplay” between these waves “takes place after gradual cessation of cerebral activity and lasts into the period when cerebral blood flow is ceased (post cardiac arrest)”. This suggests that our brains remain active for a short period even after our hearts have stopped beating.
“These findings challenge our understanding of when exactly life ends, and generate important subsequent questions, such as those related to the timing of organ donation,” Zemmar posited.
While this study revolves around one of the first recordings of a dying human brain, similar studies have been undertaken with rodents in controlled environments.
Researchers similarly found an uptick in gamma oscillations in the animals in the moments before dying, indicating that the brain organises a biological response to death that may be common across species.
The latest studyʼs authors say more research is needed, given that their theories are based on the recording of just one human patient.
However, they say the singular study provides some hope to those struggling with the loss of a loved one.
Study details
Enhanced Interplay of Neuronal Coherence and Coupling in the Dying Human Brain
Raul Vicente, Michael Rizzuto, Can Sarica, Kazuaki Yamamoto, Mohammed Sadr, Tarun Khajuria, Mostafa Fatehi, Farzad Moien-Afshari, Charles S. Haw, Rodolfo R. Llinas, Andres M. Lozano, Joseph S. Neim and Ajmal Zemmar
Published in Frontiers in Aging Neuroscience on 22 February 2022
The neurophysiological footprint of brain activity after cardiac arrest and during near-death experience (NDE) is not well understood. Although a hypoactive state of brain activity has been assumed, experimental animal studies have shown increased activity after cardiac arrest, particularly in the gamma-band, resulting from hypercapnia prior to and cessation of cerebral blood flow after cardiac arrest. No study has yet investigated this matter in humans.
Here, we present continuous electroencephalography (EEG) recording from a dying human brain, obtained from an 87-year-old patient undergoing cardiac arrest after traumatic subdural hematoma. An increase of absolute power in gamma activity in the narrow and broad bands and a decrease in theta power is seen after suppression of bilateral hemispheric responses. After cardiac arrest, delta, beta, alpha and gamma power were decreased but a higher percentage of relative gamma power was observed when compared to the interictal interval. Cross-frequency coupling revealed modulation of left-hemispheric gamma activity by alpha and theta rhythms across all windows, even after cessation of cerebral blood flow. The strongest coupling is observed for narrow- and broad-band gamma activity by the alpha waves during left-sided suppression and after cardiac arrest.
Albeit the influence of neuronal injury and swelling, our data provide the first evidence from the dying human brain in a non-experimental, real-life acute care clinical setting and advocate that the human brain may possess the capability to generate coordinated activity during the near-death period.
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