Near-death experiences could be caused
by a surge of electrical firing in the dying
brain, new research in animals suggests.
In the study, rats whose hearts were
stopped showed a surge of brain waves
associated with consciousness, according
to a new study published Aug. 12 in the
journal Proceedings of the National
Academy of Sciences. The researchers
measured the animals' brain activity on
electroencephalography (EEG) machines.
However, "whether the animals perceive
that as a white light or tunnel of light,
that's something we can't know," said
study researcher Jimo Borjigin, a
neuroscientist at the University of
Michigan at Ann Arbor.
Other experts agreed that further study is
needed to determine how the study might
apply to near-death experiences
(NDEs) in people.
There's no way to know what the rats
were experiencing while their hearts were
stopped, and other studies in dying
humans and dogs have found no brain
wave activity that was parallel to what the
researchers found in the new study, said
Dr. Sam Parnia, a resuscitation researcher
at Stony Brook University School of
Medicine in New York, who was not
involved in the study.
About 5 percent of dying patients and 10
percent of cardiac arrest patients describe
having near-death experiences. These
experiences often have similar elements,
such as a feeling of being out-of-body ,
going through a tunnel or on a river
toward a warm light, seeing lost loved
ones and being told it's not time to go
yet. Past research revealed that near-
death experiences are more vivid than
real life .
But scientists strongly disagree about the
source of these experiences. Some argue
that near-death experiences reveal the
existence of heaven or the duality
between mind and body, while others
claim the event is caused by a flood of
chemicals in the dying brain. [Inside the
Brain: A Journey Through Time ]
To sort out the issue, Borjigin and her
colleagues examined nine rats. They
induced cardiac arrest while the animals
were hooked up to EEG machines, and the
team then measured the electrical activity
in the animals' brains.
About 30 seconds after the heart had
stopped, all the animals experienced
waves of synchronized brain activity that
were characteristic of the conscious brain
. Rats that were asphyxiated with
carbon monoxide showed a similar
pattern of brain activity.
The rats' visual cortex, which processes
visual imagery, was also highly activated.
This could shed light on why NDEs are so
vivid, Borjigin said.
"They all show the fingerprints of neural
consciousness at near-death is at a much
higher level compared to the waking state.
That explains the realer-than-real human
experience," Borjigin told LiveScience.
The team believes that this electrical surge
may be a mechanism the brain uses to
rescue itself from a sharp drop in glucose
and oxygen. Though it may not work for
animals in cardiac arrest, Borjigin
speculates that this mechanism spurs
alertness or hyperawareness in less
Parnia said that after oxygen flow to the
brain stops, calcium floods brain cells as
they die, and that, rather than
consciousness, could explain the electrical
activity the researchers saw.
Finally, the study can't explain how
people can correctly recollect what
happened to them minutes after their
brain activity has flatlined and CPR has
been started, Parnia said.
Until researchers can systematically
compare the brain waves of cardiac arrest
patients who have had near-death
experiences with those who haven't,
there's no way to know what's really
going on in these experiences, Parnia