A ground-breaking study has been published in the Annals of Neurology revealing how electrical activity dissipates in the crucial moments before human beings die.
Back in the 1940s, a biologist based out of Harvard University by the name of Aristides Leão conducted a series of rather disturbing experiments relating to brain death in rabbit subjects.
Leão rendered the animals unconscious and subjected them to various brain injuries such as the application of electrical shocks, penetrating their brains with glass rods or cutting off the blood from their major arteries. All the while, Leão was monitoring the electrical activity in the brains of the animals with electrodes.
He noted that the electrical activity in the brain stopped first at the injured spot and within five minutes of the injury, this depletion of electrical activity spread to other areas of the brain before the animal eventually died.
Naturally, this is not the type of experiment that is easy to conduct on human beings outside of case studies. The most recent study on the brains of dying humans involved two men, a forty-seven-year-old patient who incurred serious brain injuries when the car he was driving was struck by a train and a fifty-seven-year-old man who is believed to have fallen down a flight of stairs.
It is likely that both of these men suffered such extreme injuries to their brain that the initial stages of electrical drainage had already happened prior to the electrodes being applied to their brain. However, the scientists working on the project were able to gather data about the final depressions of electrical activity before brain death.
Dying Brains Silence Themselves in a Dark Wave of ‘Spreading Depression’
Neurological studies in the past have found that neurons function with the utilization of charged ions. These ions are used to create electrical imbalances between themselves and their immediate surroundings, creating small shocks which are defined as neurological signals. In order to maintain this activity, the brain cells require a great deal of oxygen and chemical energy which is derived from the bloodstream.
However, once the body dies and this pipeline is shut off the neurons make a brief effort to hoard the resources that they have by falling silent. According to the researchers, all of the neurons in the brain engage in this behavior simultaneously. Later, when the cells use up all of their chemical stores, the electrical activity in the brain ceases entirely in a slow, spreading wave.
The authors of the study write that this moment marks the final throes of brain function in a dying patient. However, they do point out that this is not necessarily the moment of true death in all cases.
Research using animal subjects in the past have found that if blood and oxygen are returned to the brain cells quickly enough after the spreading wave then the neurons can spark back into action. However, if this does not happen within a couple of minutes then a stage called the ‘commitment point’ appears to be reached which cannot be reversed.