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A volley of brain body process dub the " wave of demise " may not signal the remnant after all , a new study find .
This burst , escort in the brains of dirty dog about one bit after decapitation , is a result of brain cells short miss access to oxygen and energy , but it isnot necessarily irreversible , according to the inquiry published online July 13 in the undetermined - access journal PLoS ONE . Earlier this year , another group of researchers had suggested that the " wave of death " might signal brain death .
An artist’s rendering of neurons in the human brain.
" In fact , " researchers wrote in thenew study , " this wave does not connote expiry , neither of neurons nor of individuals . " [ Top 10 Mysteries of the psyche ]
Time of last
The study highlights the trouble of nail the present moment of death . doc now think ofdeath as a process : The breath and heart and soul must quit , as must brain bodily process .
Normally these three events take place in comparatively flying succession , but that does n’t mean that all of the cellular telephone of the body are deadened . For lesson , a 2002 study put out in the Journal of Cellular and Molecular Medicine found that brain cells rent from a person several hours after death could hold out for weeks in the lab .
Of of course , brain cells outlive in a bag are n’t the same affair as a alive , witting brainiac . In a bailiwick print in January in PLoS ONE , Dutch neuroscientist Anton Coenen of Radboud University Nijmegen and his colleagues were concerned about the ethics of killing science lab stinkpot via decapitation . The dubiousness , the researcher wrote , was whether awake rats meet from aswift beheadingor they quickly lose cognizance and fend off much hurting .
To rule out , the researchers decapitated both awake and anesthetized git while measuring the electric activity in the beast ' brain with an EEG , or electroencephalograph .
In both awake and anesthetized rats , the EEG give way beat about 17 seconds after decapitation — though the researcher mention that it was at a low-spirited enough level to evoke a want of consciousness within 3.7 seconds . Then they noticed something foreign : About a minute after beheading , a slow , large electric undulation roiled through the rat ' brain .
Point of no return
Coenen ’s squad speculated that this wave was the nous finally yield up the ghost . Neurons communicate with electrical signals , which they return thanks to an dissymmetry of plus and negative charges along their mobile phone walls . This dissymmetry is call a " tissue layer potential . " Coenen and his confrere muse that the " undulation of decease " they saw on the EEG was the final loss of the membrane potential and a house of irreversible wit death .
In the new newspaper publisher , neurologist Michel van Putten of the University of Twente in the Netherlands and his colleagues used a electronic computer model to simulate thechemical changesthat bump in the wit during dying of rats . They , too , found the wave of expiry . But van Putten and his colleague do n’t harmonise that the wave represent a percentage point of no return for the brain .
Even after the wave of death , the researchers wrote , the brain cell could still theoretically rally if resupplied with oxygen and glucose , the pelf that drives the mind . As grounds , the researcher point to the head cells require from departed humans live on in the lab , as well as to a 1981 study published in the journal Stroke in which scientists saw electric activity give back to wit cells after 15 minute of oxygen loss .
Coenen was reportedly pleased that the results of the modeling experiment pit his real - world reflexion in beheaded rotter . However , Coenentold ScienceNews magazine , he still believes that the harm bring by the waving of demise is irreversible . He plans to investigate further .
