title: Monoamine Release during Unihemispheric Sleep and Unihemispheric Waking in the Fur Seal.
abstract: OBJECTIVE
  Our understanding of the role of neurotransmitters in the control of the electroencephalogram (EEG) has been entirely based on studies of animals with bilateral sleep. The study of animals with unihemispheric sleep presents the opportunity of separating the neurochemical substrates of waking and sleep EEG from the systemic, bilateral correlates of sleep and waking states.
  
  
  METHODS
  The release of histamine (HI), norepinephrine (NE), and serotonin (5HT) in cortical and subcortical areas (hypothalamus, thalamus and caudate nucleus) was measured in unrestrained northern fur seals (Callorhinus ursinus) using in vivo microdialysis, in combination with, polygraphic recording of EEG, electrooculogram, and neck electromyogram.
  
  
  RESULTS
  The pattern of cortical and subcortical HI, NE, and 5HT release in fur seals is similar during bilaterally symmetrical states: highest in active waking, reduced in quiet waking and bilateral slow wave sleep, and lowest in rapid eye movement (REM) sleep. Cortical and subcortical HI, NE, and 5HT release in seals is highly elevated during certain waking stimuli and behaviors, such as being sprayed with water and feeding. However, in contrast to acetylcholine (ACh), which we have previously studied, the release of HI, NE, and 5HT during unihemispheric sleep is not lateralized in the fur seal.
  
  
  CONCLUSIONS
  Among the studied neurotransmitters most strongly implicated in waking control, only ACh release is asymmetric in unihemispheric sleep and waking, being greatly increased on the activated side of the brain.
  
  
  CONCLUSIONS
  A commentary on this article appears in this issue on page 491.
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, and Brain Research Institute, University of California Los Angeles, Los Angeles, CA.|Severtsov Institute of Ecology and Evolution, RAS, Moscow, Russia.|Utrish Dolphinarium Ltd., Moscow, Russia.
authors.forename: Oleg I
authors.initials: OI
authors.lastname: Lyamin
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Lapierre
authors.affiliation: Utrish Dolphinarium Ltd., Moscow, Russia.|Southern Federal University, Rostov-on-Don, Russia.
authors.forename: Peter O
authors.initials: PO
authors.lastname: Kosenko
authors.affiliation: Department of Dementia and Higher Brain Function, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Kodama
authors.affiliation: Department of Dementia and Higher Brain Function, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
authors.forename: Adhil
authors.initials: A
authors.lastname: Bhagwandin
authors.affiliation: Utrish Dolphinarium Ltd., Moscow, Russia.
authors.forename: Svetlana M
authors.initials: SM
authors.lastname: Korneva
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: John H
authors.initials: JH
authors.lastname: Peever
authors.affiliation: Severtsov Institute of Ecology and Evolution, RAS, Moscow, Russia.|Utrish Dolphinarium Ltd., Moscow, Russia.
authors.forename: Lev M
authors.initials: LM
authors.lastname: Mukhametov
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, and Brain Research Institute, University of California Los Angeles, Los Angeles, CA.
authors.forename: Jerome M
authors.initials: JM
authors.lastname: Siegel
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002421:Caudate Nucleus / Q000378:metabolism; D004435:Eating / Q000502:physiology; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D005260:Female; D046069:Fur Seals / Q000502:physiology*; D006632:Histamine / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D009638:Norepinephrine / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D013788:Thalamus / Q000378:metabolism; D014851:Wakefulness / Q000502:physiology*
chemical_list: D012701:Serotonin; D006632:Histamine; D000109:Acetylcholine; D009638:Norepinephrine
keywords: acetylcholine; fur seal; histamine; marine mammals; norepinephrine; serotonin; unihemispheric sleep