Coherence and frequency in the reticular activating system (RAS)

Sleep Med Rev. 2013 Jun;17(3):227-38. doi: 10.1016/j.smrv.2012.06.002. Epub 2012 Oct 6.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Awareness / drug effects
  • Awareness / physiology
  • Benzhydryl Compounds / pharmacology
  • Beta Rhythm / drug effects
  • Beta Rhythm / physiology
  • Calcium Channels / drug effects
  • Calcium Channels / physiology
  • Central Nervous System Stimulants / pharmacology
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / physiopathology
  • Electroencephalography / drug effects
  • Humans
  • Intralaminar Thalamic Nuclei / drug effects
  • Intralaminar Thalamic Nuclei / physiopathology
  • Locus Coeruleus / drug effects
  • Locus Coeruleus / physiopathology
  • Modafinil
  • Neural Pathways / drug effects
  • Neural Pathways / physiopathology
  • Neurons / drug effects
  • Neurons / physiology
  • Pedunculopontine Tegmental Nucleus / drug effects
  • Pedunculopontine Tegmental Nucleus / physiopathology
  • Pons / physiopathology
  • Reticular Formation / drug effects
  • Reticular Formation / physiopathology*
  • Signal Processing, Computer-Assisted
  • Sleep / drug effects
  • Sleep / physiology*
  • Sodium Channels / drug effects
  • Sodium Channels / physiology
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology
  • Wakefulness / drug effects*
  • Wakefulness / physiology*
  • gamma-Aminobutyric Acid / physiology*

Substances

  • Benzhydryl Compounds
  • Calcium Channels
  • Central Nervous System Stimulants
  • Sodium Channels
  • gamma-Aminobutyric Acid
  • Modafinil