Brudzynski_1982_Behav.Brain.Res_4_33

The aim of this investigation was to examine the effects of threatening (the sight and barking of the dog) or "Neutral" (flash and tone) stimuli on the emotional-aversive response evoked by direct intracerebral application of carbachol in cats. Unilateral microinjections of carbachol in 10 microgram doses and 2 mu1 volume into anterior hypothalamic/preoptic area caused a full-blown emotional response with marked vocalization. All stimuli which might be threatening for cats caused a significant increase of vocalization. "Neutral" stimuli of comparable intensity were without effect. To investigate the effects of stimulation intensity two clocks: low and loud (difference of 27 dB), were used. The loud click significantly increased vocalization level while the low click of the same intensity as a dog's barking had no significant influence on the carbachol-induced response. Cholinergic stimulation of the anterior hypothalamic/preoptic area seems to be specifically responsible for the obtained change of perception towards increased sensitivity to any potentially threatening alteration of the environment.