Researchers observed a novel brain phenomenon in humans and animals in a coma and with an isoelectric (ie, “flat”) EEG, according to research published September 18 in PLOS One. The researchers first detected the state in a human in postanoxic coma who had received medication. They replicated the state by applying high doses of isoflurane in cats. All subjects had an EEG activity of quasi-rhythmic sharp waves that the investigators propose to call Nu-complexes. Simultaneous intracellular recordings in vivo in the cortex and hippocampus, especially in the CA3 region, demonstrated that Nu-complexes arise in the hippocampus and are transmitted to the cortex. The creation of a hippocampal Nu-complex depends on another hippocampal activity (ie, ripple activity), which is not overtly detectable at the cortical level.
—Erik Greb
Senior Associate Editor