Interrelationships of the emotionally positive and negative regions of the brain of the edible snail.

The changes in the behavior of the garden snail during self-stimulation through electrodes chronically implanted in specific regions of the brain are described in this study. The stimulation of the mesocerebral region led to an increase in the frequency of reinforced behavior, whereas stimulation of the rostral portion of the parietal ganglia led to a decrease in the frequency of reinforced behavior. An inference is reached regarding the emotional coloration of the effects of the stimulation of these regions. The interrelationships of the neurons located in the mesocerebrum and the parietal ganglia were studied in neurophysiologic experiments. It was found that the activation of the cells of the mesocerebrum inhibits the spontaneous activity of the serotoninergic cells of the pedal ganglia which sensitize the defensive reactions of the snail, and simultaneosly attenuate the sensory input of the command neurons of defensive behavior, which leads to the effective inhibition of the defensive reactions that is necessary during the activation of sexual behavior.