The team wished to know more about the specifics in humans, much of which remained enigmatic. With proper legal consent from the families of the patients – who weren’t necessarily going to die – the neurological activity of their brains were carefully monitored using a variety of electrode strips or arrays as events proceeded.
First, in 8-out-of-9 patients, the equipment picked up on the flaring of the brain cells as they tried to stop the inevitable. As this happens across the entire brain simultaneously without spreading gradually, it was termed a “nonspreading depression”.
This was then succeeded by a “spreading depolarization” (SD). Sometimes colloquially referred to as a “brain tsunami”, this involved a huge release of thermal energy as the electrochemical balances that keep brain cells alive and well break down, leading to their toxification and destruction. Then, as the patients’ oxygen levels drop precipitously, electrical activity is silenced across the brain.
Death washes over them, but, as their work revealed, it may one day not be as inevitable as it is now.
“Spreading depolarization marks the onset of the toxic cellular changes that eventually lead to death, but is not a marker of death per se, since depolarization is reversible – up to a point – with restoration of energy supply,” lead author Professor Jens Dreier, of Charité’s Center for Stroke Research, told IFLScience.
This paper’s data, then, demarcates the point at which cellular resurrection remains possible. There’s a lot more research to be done before this can become a reality, though: Dreier notes that SD is only just beginning to be understood. Like death itself, this neurological facet of it is a “complex phenomenon” for which “there are no easy answers”.