Disruptive effect of the mesencephalic reticular formation on tonic immobility in guinea pigs

Cholinergic stimulation of the mesencephalic reticular formation with carbachol impairs the induction of tonic immobility (TI) by restreining maneuvers and reduces the duration of immobility episodes in guiena pigs TI which permits the animal to evaluate the best6 time for escape. It is possible that this monitoring inolves cirucits and neurotransmitters other than the ascending cholinergic system origination in the mesencephalic reticular formation