Participation of the brainstem visceral centers in the formation of emotional and behavioral reactions.

The effect of electrical stimulation of the region of the medial parabrachial nucleus on the behavior of albino rats is studied in chronic experiments. Stimulation of this region is found to cause an increase in the rate of respiration and inhibition of natural behavioral reactions and reactions elicited by stimulation of the nuclei of the amygdala, lateral hypothalamus, and the zona incerta of the brain. Similar inhibitory effects are noted for stimulation of certain zones of the midbrain cuneate nucleus and regions of the pontine suture. The inhibitory influence of stimulation of the parabrachial nucleus on behavior is thought to be due to the switching-on of the central mechanisms of inhibition of motor activity in animals.