title: Dissociated wake-like and sleep-like electro-cortical activity during sleep.
abstract: Sleep is traditionally considered a global process involving the whole brain. However, recent studies have shown that sleep depth is not evenly distributed within the brain. Sleep disorders, such as sleepwalking, also suggest that EEG features of sleep and wakefulness might be simultaneously present in different cerebral regions. In order to probe the coexistence of dissociated (wake-like and sleep-like) electrophysiological behaviors within the sleeping brain, we analyzed intracerebral electroencephalographic activity drawn from sleep recordings of five patients with pharmacoresistant focal epilepsy without sleep disturbances, who underwent pre-surgical intracerebral electroencephalographic investigation. We applied spectral and wavelet transform analysis techniques to electroencephalographic data recorded from scalp and intracerebral electrodes localized within the Motor cortex (Mc) and the dorso-lateral Prefrontal cortex (dlPFc). The Mc showed frequent Local Activations (lasting from 5 to more than 60s) characterized by an abrupt interruption of the sleep electroencephalographic slow waves pattern and by the appearance of a wake-like electroencephalographic high frequency pattern (alpha and/or beta rhythm). Local activations in the Mc were paralleled by a deepening of sleep in other regions, as expressed by the concomitant increase of slow waves in the dlPFc and scalp electroencephalographic recordings. These results suggest that human sleep can be characterized by the coexistence of wake-like and sleep-like electroencephalographic patterns in different cortical areas, supporting the hypothesis that unusual phenomena, such as NREM parasomnias, could result from an imbalance of these two states.
authors: Centre of Epilepsy Surgery C. Munari, Niguarda Hospital, Milan, Italy. lino.nobili@ospedaleniguarda.it
authors: Lino
authors: L
authors: Nobili
authors: Michele
authors: M
authors: Ferrara
authors: Fabio
authors: F
authors: Moroni
authors: Luigi
authors: L
authors: De Gennaro
authors: Giorgio Lo
authors: GL
authors: Russo
authors: Claudio
authors: C
authors: Campus
authors: Francesco
authors: F
authors: Cardinale
authors: Fabrizio
authors: F
authors: De Carli
mesh_terms: D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology; D000704:Analysis of Variance; D001611:Beta Rhythm / Q000502:physiology; D003700:Delta Rhythm; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D014851:Wakefulness / Q000502:physiology*; D058067:Wavelet Analysis; D055815:Young Adult