Surge of neurophysiological coherence and connectivity in the dying brain.
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.
Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA. borjigin@umich.edu
Jimo
J
Borjigin
UnCheol
U
Lee
Tiecheng
T
Liu
Dinesh
D
Pal
Sean
S
Huff
Daniel
D
Klarr
Jennifer
J
Sloboda
Jason
J
Hernandez
Michael M
MM
Wang
George A
GA
Mashour
D000818:Animals; D001921:Brain / Q000502:physiology*; D001926:Brain Death; D004569:Electroencephalography; D005260:Female; D006323:Heart Arrest / Q000503:physiopathology; D008297:Male; D051381:Rats; D017208:Rats, Wistar
consciousness; global hypoxia; global ischemia; near-death experience