A landmark study involving a dying person’s brain activity could provide an explanation for reports of people vividly recalling their lives in near-death experiences.
The findings, published Tuesday in the journal Frontiers in Ageing Neuroscience, also raise important questions related to the timing of organ donation.
Neuroscientists, including Raul Vicente of the University of Tartu, Estonia, were initially studying the brain waves of an 87-year-old epilepsy patient for seizures using an electroencephalography (EEG) device, but in the middle of the study, the patient had a heart attack and died.
The EEG recording shed light on about 900 seconds of the person’s brain activity as they died, and the scientists attempted to investigate what specifically happened in the 30 seconds before and after the heart stopped beating.
The findings revealed that as the person was dying, there was an increase in brain waves known as gamma oscillations that typically occur during dreaming and memory retrieval, as well as others such as delta, theta, alpha, and beta oscillations.
Brain waves are rhythmic electrical activity in normal living human brains, and different types of these waves are linked to different states.
Citing an example, researchers said gamma oscillations are linked to high-cognitive functions like concentrating, dreaming, meditation, memory retrieval and conscious perception, like those linked to memory flashbacks.
And studies have also shown that alpha waves, which oscillate in the frequency of 8-12 hertz, could play a role in filtering out distracting sensory information and helping pay attention.
Based on the existing knowledge of the activities associated with different brain waves, scientists speculate the dying 87-year old person may have been making a “last recall of life.”
“Given that cross-coupling between alpha and gamma activity is involved in cognitive processes and memory recall in healthy subjects, it is intriguing to speculate that such activity could support a last ‘recall of life’ that may take place in the near-death state,” researchers wrote in the study.
“Through generating oscillations involved in memory retrieval, the brain may be playing a last recall of important life events just before we die, similar to the ones reported in near-death experiences,” study co-author Ajmal Zemmar, a neurosurgeon at the University of Louisville in the US, said in a statement.
While this is the first such study in humans, scientists have previously observed similar changes in gamma oscillations in rats kept in controlled environments, indicating that, during death, the brain organises and executes a biological response that may be conserved across species.
“Despite these caveats, the overall similarity in oscillatory changes between the highly controlled experimental rodent study and the present work suggests that the brain may pass through a series of stereotyped activity patterns during death,” scientists wrote in the study.
But since the new research is based on a single patient who had also suffered injury, seizures and swelling, researchers said the interpretation of the data may be complicated, adding that there is a need to investigate more cases and see the latest results as a “source of hope.”
“Something we may learn from this research is: although our loved ones have their eyes closed and are ready to leave us to rest, their brains may be replaying some of the nicest moments they experienced in their lives,” Dr Zemmar added.
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