As we die, do our brains play our most important memories?

As we die, do our brains play our most important memories? ...

A surprising new study uncovered a never-before-seen perspective into the dying brain in February 2022.

For the first time, a medical case report recorded the brain activity of a patient before, during, and after a cardiac arrest. The authors identified a link between these characteristic activity patterns, the accounts of persons who have had near-death experiences (NDEs) and other neuroimaging studies to suggest that the brain activity might be indicative of a last recall of a lifes memories. Lets take a deep dive into these findings.

An unusual case study

The only problem with brain activity analysis in the papers before and after death is that it has never been done before. Achieved by a neurosurgeon, I was very, very surprised when I saw them and informed me, look, I have these recordings, and we believe they are unique, according to Dr. Raul Vicente, the head of the computational neuroscience lab at the University of Tartu.

Vicente is a physicist by training but has spent the last 15 years working with neuroscientists, according to an arrangement that meant he was hired out by Dr. Ajmal Zemmar, a neurosurgeon who treated the patient, to analyze the data.

When asked why the patient''s life was unusual, Vicente says, it''s easier to understand why the findings are unique. The 87-year-old patient involved had been ejected from the hospital, showing tremors and twitches that could cause permanent brain damage and death. Zemmars'' team arranged electrodes across the patient''s scalp in a gentle 10-20 pattern that ensured equal electrode spacing. During the EEG recording, the patient was arrested.

The patient who died after consulting with the patient''s family and noting his do not resuscitate status.

There''s no need to have a complete EEG rig attached to a dying patient in virtually any other clinical case, therefore the only existing comparable data comes from more limited EEG data from patients in palliative care. The whole setup used in the Vicente and colleagues study is unique in its depth and its recording of the last minutes of a persons life.

The why and how of brain activity

The researchers'' next task was to analyze this one-of-a-kind dataset. According to Vicente, the data exhibited an increase in gamma wave activity in the moments before the patient died. Vicente is also first to claim that, with a sample size of one, the conclusions must necessarily be based on other sources of information.

Vicente argues that even if the reason or how of these signatures remains unclear, one of them is storage of information or the recall of information or memories. Our ability to adapt these cognitive abilities to particular brain waves has been proven from decades of electrophysiology research, which has helped establish a picture of what brain activity does during, for example, behavioral tasks.

Death is a once-in-a-lifetime event, but it does not provide much space for post-game analysis or feedback. Fortunately, there is a wide spectrum of evidence from individuals who have approached the door without passing through.

Exploring near-death experiences

These are individuals who have experienced near-death experiences (NDEs) which, according to Vicente, is always observed. These individuals also have memory limitations. They remember significant experiences in their lives.

Thousands of data points from people who were interviewed following, for example, being resuscitated following an NDE diagnosis are missing. Around 10% to 10% of respondents have received NDEs, according to Vicente.

Vicente believes that by putting these various components of evidence together, one might hypothesize that the increase in gamma activity is the neurophysiological substrate of the experience of people who have NDEs.

One of the few insights we will ever get into the last seconds of the brains function is a brief, yet powerful window into the highs and lows of existence, which takes decades into seconds and allows the mind to view the landscape of life from a final peak perspective.

It''s not a simple interpretation.

The limitations of understanding the brain

What the study highlights on a deeper level is the limitations of the tools we currently use to analyze brains'' data. While gamma activity might increase during recall, it is also increased by other cognitive activities, thus we can only suspect that memory recall was the work done by the dying patients brain.

The gamma increase is even assumed by cognitive changes, according to Vicente, as his study reveals several different confounding factors that might have had contributed to their findings. Perhaps the patients'' absence of oxygen or an increase in CO2 levels were to blame for his high gamma activity. There is little space to argue whether the data is actually accurate.

Techniques such as EEG and magnetic resonance imaging (MRI) may be beneficial when given sufficient knowledge to play with. Vicente highlights innovative research into dreams'' content. Through the experiments, researchers tested evidence from lucid dreamers capable of guiding their dreams. But it''s not that you can, therefore, you can fully recreate the content correctly. Some very gross aspects of certain subjective experiences, such as dreams, can be recovered to some extent.

As our technology advances, perhaps techniques such as MRI and EEG will be able to make more accurate predictions from smaller study sample sizes. However, a recent study of MRI research reveals that many funded neuroimaging studies utilize sample sizes that are too small and underpowered. The Vicentes study is a reminder both of the human brains'' complexity and how limited we are in our ability to understand and decode it for the time being.

Ruairi J Mackenzie, the senior science writer for Technology Networks, spoke with Raul Vicente.

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