title: Selective coupling between theta phase and neocortical fast gamma oscillations during REM-sleep in mice.
abstract: BACKGROUND
  The mammalian brain expresses a wide range of state-dependent network oscillations which vary in frequency and spatial extension. Such rhythms can entrain multiple neurons into coherent patterns of activity, consistent with a role in behaviour, cognition and memory formation. Recent evidence suggests that locally generated fast network oscillations can be systematically aligned to long-range slow oscillations. It is likely that such cross-frequency coupling supports specific tasks including behavioural choice and working memory.
  
  
  RESULTS
  We analyzed temporal coupling between high-frequency oscillations and EEG theta activity (4-12 Hz) in recordings from mouse parietal neocortex. Theta was exclusively present during active wakefulness and REM-sleep. Fast oscillations occurred in two separate frequency bands: gamma (40-100 Hz) and fast gamma (120-160 Hz). Theta, gamma and fast gamma were more prominent during active wakefulness as compared to REM-sleep. Coupling between theta and the two types of fast oscillations, however, was more pronounced during REM-sleep. This state-dependent cross-frequency coupling was particularly strong for theta-fast gamma interaction which increased 9-fold during REM as compared to active wakefulness. Theta-gamma coupling increased only by 1.5-fold.
  
  
  CONCLUSIONS
  State-dependent cross-frequency-coupling provides a new functional characteristic of REM-sleep and establishes a unique property of neocortical fast gamma oscillations. Interactions between defined patterns of slow and fast network oscillations may serve selective functions in sleep-dependent information processing.
authors.affiliation: Institute for Physiology and Pathophysiology, University Heidelberg, Heidelberg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Scheffzük
authors.forename: Valeriy I
authors.initials: VI
authors.lastname: Kukushka
authors.forename: Alexei L
authors.initials: AL
authors.lastname: Vyssotski
authors.forename: Andreas
authors.initials: A
authors.lastname: Draguhn
authors.forename: Adriano B L
authors.initials: AB
authors.lastname: Tort
authors.forename: Jurij
authors.initials: J
authors.lastname: Brankačk
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D004594:Electrophysiology / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019579:Neocortex / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009991:Oscillometry / Q000379:methods*; D010296:Parietal Lobe / Q000473:pathology; D011209:Power, Psychological; D012890:Sleep / Q000502:physiology; D012895:Sleep, REM / Q000502:physiology*; D013997:Time Factors