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Neocortical 40 Hz oscillations during carbachol‐induced rapid eye movement sleep and cataplexy
Author(s) -
Torterolo Pablo,
CastroZaballa Santiago,
Cavelli Matías,
Chase Michael H.,
Falconi Atilio
Publication year - 2016
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13151
Subject(s) - wakefulness , neuroscience , carbachol , psychology , rapid eye movement sleep , sleep spindle , eye movement , non rapid eye movement sleep , neuroscience of sleep , slow wave sleep , electroencephalography , stimulation
Higher cognitive functions require the integration and coordination of large populations of neurons in cortical and subcortical regions. Oscillations in the gamma band (30–45 Hz) of the electroencephalogram ( EEG ) have been involved in these cognitive functions. In previous studies, we analysed the extent of functional connectivity between cortical areas employing the ‘mean squared coherence' analysis of the EEG gamma band. We demonstrated that gamma coherence is maximal during alert wakefulness and is almost absent during rapid eye movement ( REM ) sleep. The nucleus pontis oralis ( NPO ) is critical for REM sleep generation. The NPO is considered to exert executive control over the initiation and maintenance of REM sleep. In the cat, depending on the previous state of the animal, a single microinjection of carbachol (a cholinergic agonist) into the NPO can produce either REM sleep [ REM sleep induced by carbachol ( REM c)] or a waking state with muscle atonia, i.e. cataplexy [cataplexy induced by carbachol ( CA )]. In the present study, in cats that were implanted with electrodes in different cortical areas to record polysomnographic activity, we compared the degree of gamma (30–45 Hz) coherence during REM c, CA and naturally‐occurring behavioural states. Gamma coherence was maximal during CA and alert wakefulness. In contrast, gamma coherence was almost absent during REM c as in naturally‐occurring REM sleep. We conclude that, in spite of the presence of somatic muscle paralysis, there are remarkable differences in cortical activity between REM c and CA , which confirm that EEG gamma (≈40 Hz) coherence is a trait that differentiates wakefulness from REM sleep.