That hyperconscious state that some have during cardiac arrest that is called 'near death experience' may simply be a feature of the activity of a dying brain. This is the first direct scientific evidence of brain activity during cardiac arrest in a mammalian brain. Once the brain actually does die, there is no activity. Prior to this study, figuring out at what point in a near death experience the experience actually occurred was a matter of conjecture. Now we have some evidence of what is happening in a brain during the process of dying. At the moment this has to be extrapolated to humans, but it is a good starting point.
------------------- SURGE OF NEUROPHYSIOLOGICAL COHERENCE AND CONNECTIVITY IN THE DYING BRAIN Jimo Borjigina,b,c, UnCheol Leed,, Tiecheng Liua, Dinesh Pald, Sean Huffa, Daniel Klarrd, Jennifer Slobodaa, Jason Hernandeza, Michael M. Wanga,b,c,e, and George A. Mashourc,d Author Affiliations Departments of a Molecular and Integrative Physiology, b Neurology, and d Anesthesiology, and c Neuroscience Graduate Program University of Michigan Ann Arbor, MI 48109 eVeterans Administration Ann Arbor, MI 48105 Edited by Solomon H. Snyder, The Johns Hopkins University School of Medicine, Baltimore, MD, and approved July 9, 2013 (received for review May 2, 2013) ABSTRACT The brain is assumed to be hypoactive during cardiac arrest. However, the neurophysiological state of the brain immediately following cardiac arrest has not been systematically investigated. In this study, we performed continuous electroencephalography in rats undergoing experimental cardiac arrest and analyzed changes in power density, coherence, directed connectivity, and cross-frequency coupling. We identified a transient surge of synchronous gamma oscillations that occurred within the first 30 s after cardiac arrest and preceded isoelectric electroencephalogram. Gamma oscillations during cardiac arrest were global and highly coherent; moreover, this frequency band exhibited a striking increase in anterior–posterior-directed connectivity and tight phase-coupling to both theta and alpha waves. High-frequency neurophysiological activity in the near-death state exceeded levels found during the conscious waking state. These data demonstrate that the mammalian brain can, albeit paradoxically, generate neural correlates of heightened conscious processing at near-death. http://www.pnas.org/content/early/2013/08/08/1308285110.abstract
