Jason J. Braithwaite, a researcher in visual cognitive neuroscience has wrote a critique on Dr. Pim Van Lommel's study on nde's. His criticisms are that survivalist's nde researchers have completely misunderstood what the dying brain hypothesis really says. According to this theory, as formulated by Susan Blackmore and others, it's not the mere presence of anoxia that causes vivid seeming hallucinations, but the rate of its onset. If it comes on too rapidly, the patient will lose consciousness and black out, so no conscious experience or memory could occur.
He also mentions studies done on epileptics that show large scale seizure activity occurring in deep sub-cortical regions, that does not register at all on scalp-based EEG traces - an indication that an EEG is an unreliable measure of neural activity.
True, their maybe some deep brain activity that the instruments may not detect. The question really is not that their is no brain activity going on, but is it the specific form as regarded by contemporary neuroscience as the necessary condition of conscious experience. Activity of this form is eminently detectable by current EEG technology, and as we have already shown, it is abolished both by adequate general anesthesia and by cardiac arrest.
He also cites evidence that inter-ictal discharges in the hippocampus or amygdala alone are more than sufficient to produce complex meaningful hallucinations - no involvement from the cortex is necessary.
Yeah ok hallucinations which is the keyword here. Their are clear differences in nde's that happen in cardiac arrest or clinical death compared to electrical stimulation to the brain. This has been shown not just by nde researchers but also by other neuroscientists. Such as Dr. Edward Kelly and Dr.Emily Kelly in their book called the Irreducible Mind.