Reply to Greyson et al.: Experimental evidence lays a foundation for a rational understanding of near-death experiences

Abstract

Greyson et al. (1) state that it is misleading to describe the rat brain as hyperaroused because the EEG power at near death was only a small fraction of that of the waking state in our study (2). However, they neglect to note that we showed that the power of EEG signals associated with consciousness increased in every rat we tested [see figure 2A of Borjigin et al. (2)]. Greyson et al. posit that “the pertinent question here is not whether there is any brain electrical activity at all after cardiac arrest, but whether there is activity of the type currently thought to be necessary for conscious experience.” In complete accordance with their opinion, our entire study (2) is devoted to demonstrating the presence of electrical fingerprints of consciousness in the near-death brain. We report increased power and global synchrony in the gamma bandwidth, two neurophysiologic features associated with conscious processing. Moreover, this gamma band exhibits an eightfold increase in top-down information processing (thought to be a key element of consciousness) and fivefold increase in bottom-up information flow (thought to represent sensory information processing) at near death. In addition, we found tight coupling of gamma bands with both theta and alpha bands, yet another indicator of conscious information processing in the postarrest brain. Thus, our work (2) directly answers the concern of Greyson et al.