Effect of some intracerebrally administered drugs on a conditioned reflex in the cat

Abstract

Injection of carbachol into the anterior hypothalamus or thalamus (intralaminar nuclei) in freely-moving cats caused a dose related inhibition of alimentary conditioned reflex performance (CRP). The inhibition directly correlated with the intensity of the emotional (rage) reaction also elicitable by carbachol from these parts of the brain. The inhibition of CRP after intrahypothalamic or intrathalamic carbachol application seemed to be a secondary effect due exclusively to the altered emotional state of the animal. Injection of carbachol into the dorsal or ventral hippocampus as well as the basal or central part of the amygdala also inhibited CRP. This inhibitory effect could only be observed when the EEG pattern of the animals showed local or propagated seizure discharges. Thus the inhibition of CRP after intralimbic carbachol application seemed to be a secondary effect due to pathologic alterations in the electrical activity of the brain. All the above effects of carbachol were easily counteracted by topical pretreatment with a few μg of atropine. Nicotine and noradrenaline were ineffective in all regions investigated.