Human Brain Activity Patterns beyond the Isoelectric Line of Extreme Deep Coma
Open Access
- 18 September 2013
- journal article
- clinical trial
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 8 (9), e75257
- https://doi.org/10.1371/journal.pone.0075257
Abstract
The electroencephalogram (EEG) reflects brain electrical activity. A flat (isoelectric) EEG, which is usually recorded during very deep coma, is considered to be a turning point between a living brain and a deceased brain. Therefore the isoelectric EEG constitutes, together with evidence of irreversible structural brain damage, one of the criteria for the assessment of brain death. In this study we use EEG recordings for humans on the one hand, and on the other hand double simultaneous intracellular recordings in the cortex and hippocampus, combined with EEG, in cats. They serve to demonstrate that a novel brain phenomenon is observable in both humans and animals during coma that is deeper than the one reflected by the isoelectric EEG, and that this state is characterized by brain activity generated within the hippocampal formation. This new state was induced either by medication applied to postanoxic coma (in human) or by application of high doses of anesthesia (isoflurane in animals) leading to an EEG activity of quasi-rhythmic sharp waves which henceforth we propose to call ν-complexes (Nu-complexes). Using simultaneous intracellular recordings in vivo in the cortex and hippocampus (especially in the CA3 region) we demonstrate that ν-complexes arise in the hippocampus and are subsequently transmitted to the cortex. The genesis of a hippocampal ν-complex depends upon another hippocampal activity, known as ripple activity, which is not overtly detectable at the cortical level. Based on our observations, we propose a scenario of how self-oscillations in hippocampal neurons can lead to a whole brain phenomenon during coma.This publication has 40 references indexed in Scilit:
- Spatiotemporal Coupling between Hippocampal Acetylcholine Release and Theta OscillationsIn VivoJournal of Neuroscience, 2010
- Opening of the blood–brain barrier during isoflurane anaesthesiaEuropean Journal of Neuroscience, 2008
- Hypersensitivity of the Anesthesia-Induced Comatose BrainJournal of Neuroscience, 2007
- Sleep function and synaptic homeostasisSleep Medicine Reviews, 2006
- Slow intrinsic spikes recorded in vivo in rat CA1–CA3 hippocampal pyramidal neuronsExperimental Neurology, 1990
- Two-stage model of memory trace formation: A role for “noisy” brain statesNeuroscience, 1989
- Hippocampal sharp waves: Their origin and significanceBrain Research, 1986
- ASSESSMENT OF COMA AND IMPAIRED CONSCIOUSNESS: A Practical ScaleThe Lancet, 1974
- Genesis of epileptic interictal spikes. New knowledge of cortical feedback systems suggests a neurophysiological explanation of brief paroxysmsBrain Research, 1973
- Entorhinal Activation of Dentate Granule CellsActa Physiologica Scandinavica, 1966