Neuroscientists have been working to understand the secrets of the brain, including what happens in the final moments before a person dies. A team of researchers from the University of Michigan has identified a surge of gamma waves in the brains of two patients who were on the brink of death. The scientists analyzed electroencephalogram (EEG) and electrocardiogram (ECG) signals in four patients in a coma before and after the withdrawal of ventilatory support.
The researchers found that two of the patients exhibited a global hypoxia marked by stimulated gamma activities. The gamma wave was located in a part of the brain known as hot zone, which has in the past been associated with people dreaming and seizure patients who report having visual hallucinations.
Although the patients did not survive to describe what they saw due to the elevated gamma waves, survivors of clinical death have reported experiencing internal perception of bright light or familiar faces, which suggests a preserved capacity in the dying brain to process internally generated vision. The researchers suggest the need to reevaluate the role of the brain during cardiac arrest.
In a separate study, scientists have found a way to decode a stream of words in the brain using MRI scans and artificial intelligence. The system reconstructs the gist of what a person hears or imagines, rather than trying to replicate each word.
The technology, which only works when the participant is actively cooperating with scientists, can decode the semantics and meaning behind the words. This breakthrough could help improve communication for people with conditions such as locked-in syndrome.
As scientists continue to unravel the mysteries of the brain, these two studies represent significant steps forward in our understanding of brain activity during death and the potential for advanced communication technology.
“Brain function around the time of cardiac arrest is poorly understood. While the loss of overt consciousness is invariably associated with cardiac arrest, it is unclear whether patients can possess covert consciousness during the dying process,” scientists said in the paper.
Scientists looked into cases from Michigan Medicine, the University of Michigan‘s academic medical center, of patients who died in the neuro-intensive care unit since 2014. They noticed a sharp jump in gamma waves in one part of the brain that established a long-range connection across both hemispheres of the brain.
“Internal perception of bright light or familiar faces reported by survivors of clinical death (3) suggests a preserved capacity in the dying brain to process internally generated vision. It remains to be determined if the posterior cortical regions are activated in the dying human brain,” the paper read.
The gamma wave was initially located in a part of the brain known as hot zone, which has in the past been associated with people dreaming, and seizure patients who report having visual hallucinations. The hot zone in the brain is a region postulated to be critical for conscious processing.
Dying Brains can still be active – Research says
However, the patients did not survive to describe what they saw due to the elevated gamma waves.
“While the mechanisms and physiological significance of these findings remain to be fully explored, these data demonstrate that the dying brain can still be active. They also suggest the need to reevaluate the role of the brain during cardiac arrest,” the team concluded in the paper.
Interestingly, Scientists have found a way to decode a stream of words in the brain using MRI scans and artificial intelligence.
The system reconstructs the gist of what a person hears or imagines, rather than trying to replicate each word, a team reports in the journal Nature Neuroscience.
“It’s getting at the ideas behind the words, the semantics, the meaning,” says Alexander Huth, an author of the study and an assistant professor of neuroscience and computer science at The University of Texas at Austin.
