"We don't have any rough and ready way to take a measurement and assign a meaning to it with regards to conscious content," said neurologist Nicholas Schiff of the Weill Cornell Medical College, who was not involved in the study.
Borjigin also noted an increase in EEG activity that has been tied to visual stimulation in humans that could possibly explain the very bright light that survivors describe.
The researchers also confirmed the effect using another form of death, asphyxiation via carbon dioxide inhalation. The same highly aroused features were seen in a nearly identical pattern.
Schiff find the study "very interesting" and novel, but is very skeptical about any near-death interpretations.
"There's no intrinsic reason to believe that these rats are in some heightened state of awareness," he said. He believes the spike in activity is simply a shock-to-the-system response by the brain cells to a major change in physiology.
While the study does look at the data within the context of near-death experiences, both Borjigin and Mashour hesitate to state a direct connection between the two. The links are merely speculative at this point and provide a framework for a human study, said Borjigin.
Even if the EEG patterns after cardiac arrest appear similar to the those of the awake state, Schiff cautioned that the same rules may not apply when the brain's playing field has changed drastically due to lack of blood flow. He does think that a similar surge in activity, if seen in rat brain, would translate to human brain as well.
There are some case reports by doctors who have witnessed a surge in EEG activity in their patients at the point of death, but no systematic study has been done.