title: Coherence and frequency in the reticular activating system (RAS).
abstract: This review considers recent evidence showing that cells in the reticular activating system (RAS) exhibit (1) electrical coupling mainly in GABAergic cells, and (2) gamma band activity in virtually all of the cells. Specifically, cells in the mesopontine pedunculopontine nucleus (PPN), intralaminar parafascicular nucleus (Pf), and pontine dorsal subcoeruleus nucleus dorsalis (SubCD) (1) show electrical coupling, and (2) all fire in the beta/gamma band range when maximally activated, but no higher. The mechanism behind electrical coupling is important because the stimulant modafinil was shown to increase electrical coupling. We also provide recent findings demonstrating that all cells in the PPN and Pf have high threshold, voltage-dependent P/Q-type calcium channels that are essential to gamma band activity. On the other hand, all SubCD, and some PPN, cells manifested sodium-dependent subthreshold oscillations. A novel mechanism for sleep-wake control based on transmitter interactions, electrical coupling, and gamma band activity is described. We speculate that continuous sensory input will modulate coupling and induce gamma band activity in the RAS that could participate in the processes of preconscious awareness, and provide the essential stream of information for the formulation of many of our actions.
authors.affiliation: Center for Translational Neuroscience, Department of Neurobiology & Dev. Sci., University of Arkansas for Medical Sciences, 4301 West Markham St., Slot 847, Little Rock, AR 72205, USA. GarciaRillEdgar@uams.edu
authors.forename: Edgar
authors.initials: E
authors.lastname: Garcia-Rill
authors.forename: Nebojsa
authors.initials: N
authors.lastname: Kezunovic
authors.forename: James
authors.initials: J
authors.lastname: Hyde
authors.forename: Christen
authors.initials: C
authors.lastname: Simon
authors.forename: Paige
authors.initials: P
authors.lastname: Beck
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Urbano
mesh_terms: D000818:Animals; D001364:Awareness / Q000187:drug effects / Q000502:physiology; D001559:Benzhydryl Compounds / Q000494:pharmacology; D001611:Beta Rhythm / Q000187:drug effects / Q000502:physiology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology; D004569:Electroencephalography / Q000187:drug effects; D006801:Humans; D020646:Intralaminar Thalamic Nuclei / Q000187:drug effects / Q000503:physiopathology; D008125:Locus Coeruleus / Q000187:drug effects / Q000503:physiopathology; D000077408:Modafinil; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D045042:Pedunculopontine Tegmental Nucleus / Q000187:drug effects / Q000503:physiopathology; D011149:Pons / Q000503:physiopathology; D012154:Reticular Formation / Q000187:drug effects / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014851:Wakefulness / Q000187:drug effects* / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D001559:Benzhydryl Compounds; D015220:Calcium Channels; D000697:Central Nervous System Stimulants; D015222:Sodium Channels; D005680:gamma-Aminobutyric Acid; D000077408:Modafinil