8. The Brain
Contrary to popular belief, the brain isn’t the last thing to go at the moment of death. Typically, the death of the body follows shortly after brain death.
In most nations, “brain death” is generally defined as zero activity within the brain stem, which is the most rudimentary portion of the brain. From there, all other brain activity and larger systems operate. The brain stem links the spinal cord (and thus the entire nervous system) with the portions of the brain that control thought and emotion, like the prefrontal cortex or the hippocampus.
As in zombie movies, if the brain stem is dead, the person likely dies with it. In essence, the death of the brain stem is the death of the organism because the brain stem controls all the vital bodily functions like respiration.
Without a functioning brain stem, all these systems begin to shut down. Currently, the death of the brain stem is the final moment of brain death and often the point of legal death in most countries. When the heart stops beating, it’s estimated that the brain can survive up to a maximum of about six minutes. Even then, brain damage will be significant.
No matter what starts the chain of events that causes a person to die, the death of the brain stem is always the cause of death—even for a heart attack or drowning victim. If the brain dies, the body may live on for a few minutes. But a body isn’t truly dead until the brain stem loses all functioning.
7. Brain Activity
Here’s another counterintuitive occurrence at the moment of death: As the body becomes deprived of oxygen on the cellular level, brain activity actually heightens. Although ethical doctors aren’t using fMRI machines on their dying patients, research shows that the brain goes berserk in animals, lighting up like a fireworks display at the time of death.
When a rat’s heart stops, its brain goes into overdrive in all areas known to produce consciousness. This process isn’t wholly understood, but it’s believed to produce what we call the near-death experience—the extraordinary sensations, sights, sounds, memories, and other experiences of people who are revived shortly after death.