title: Functional microstates within human REM sleep: first evidence from fMRI of a thalamocortical network specific for phasic REM periods.
abstract: High thalamocortical neuronal activity characterizes both, wakefulness and rapid eye movement (REM) sleep, but apparently this network fulfills other roles than processing external information during REM sleep. To investigate thalamic and cortical reactivity during human REM sleep, we used functional magnetic resonance imaging with simultaneous polysomnographic recordings while applying acoustic stimulation. Our observations indicate two distinct functional substates within general REM sleep. Acoustic stimulation elicited a residual activation of the auditory cortex during tonic REM sleep background without rapid eye movements. By contrast, periods containing bursts of phasic activity such as rapid eye movements appear characterized by a lack of reactivity to sensory stimuli. We report a thalamocortical network including limbic and parahippocampal areas specifically active during phasic REM periods. Thus, REM sleep has to be subdivided into tonic REM sleep with residual alertness, and phasic REM sleep with the brain acting as a functionally isolated and closed intrinsic loop.
authors.affiliation: Max Planck Institute of Psychiatry, Kraepelinstr. 10, D-80804 Munich, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Wehrle
authors.forename: Christian
authors.initials: C
authors.lastname: Kaufmann
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Wetter
authors.forename: Florian
authors.initials: F
authors.lastname: Holsboer
authors.forename: Dorothee P
authors.initials: DP
authors.lastname: Auer
authors.forename: Thomas
authors.initials: T
authors.lastname: Pollmächer
authors.forename: Michael
authors.initials: M
authors.lastname: Czisch
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001303:Auditory Cortex / Q000166:cytology / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways; D020534:Parahippocampal Gyrus / Q000166:cytology / Q000502:physiology; D017286:Polysomnography; D012895:Sleep, REM / Q000502:physiology*; D013788:Thalamus / Q000166:cytology / Q000502:physiology*