When physicians find that a coma patient’s EEG has flatlined, they declare the patient brain dead. But new research out of the University of Montreal has shown that brain activity can continue, even when there is no observable activity on an EEG. After a physician observed cerebral activity in a coma patient with a flatlined EEG, researchers recreated the situation in cats. Using isoflurane, the researchers placed the cats in a very deep (but reversible) coma. Although the cats had a flatlined EEGs, the researchers were able to observe regular cellular activity in the hippocampus. These oscillations were similar to what the physician had observed in the human patient. Lest people worry that coma patients had been inadvertently killed when life support was switched off, the researchers say that this isn’t the case. Brain death is one of only many criteria factored into the decision to remove a patient from life support.
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Journal article: Human Brain Activity Patterns beyond the Isoelectric Line of Extreme Deep Coma. PLoS ONE, 2013. doi:10.1371/journal.pone.0075257
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