Cholinergic mechanisms involved in cortical activation during arousal.
Spontaneous and evoked cortical electrical activity of the post-central gyrus was studied in 5 unparalyzed, unanesthetized monkeys during slow-wave sleep (SWS) and wakefulness (W), before and after the administration of a muscarinic anticholinergic agents, hyoscine. It was found that hyoscine reproduces the effect of SWS: (1) on spontaneous EEG activity and single unit discharges of the somatosensory cortes without any concomitant behavioral sleep; and (2) on surface evoked potentials and reactivity of cortical neurons to peripheral electrical stimulation. Short episodes of EEG desynchronization were noted in the alert state after hyoscine suggesting the existence of a phasic activating system unblocked by hyoscine. These observations support the concept of an EEG-behavior dissociation produced by muscarinic anticholinergic agents and extend this concept to single neuron activity. These observations also lead to the conclusion that tonic EEG activation during arousal may be cholinergic at the cortical level even though other neurotransmitters may be involved.
D000109:Acetylcholine / Q000502:physiology*; D000818:Animals; D001143:Arousal; D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials; D008251:Macaca; D008839:Microelectrodes; D012601:Scopolamine / Q000494:pharmacology; D012890:Sleep; D013003:Somatosensory Cortex / Q000502:physiology
D012601:Scopolamine; D000109:Acetylcholine