Ｑ31.What is the relationship between emotions and a brain?

Ａ.A brain has the circuit for emotions.<br>
<br>
　　Brain disorders research has made clear the place where emotions work. Look at the picture.<br>
　　The path to recognize what emotion is felt is: sensory receptor → sensory cortex → sensory association cortex → amygdala → prefrontal cortex → motor association cortex → motor cortex → motor organ.<br>
　　The path to recognize quantity of emotion is: internal organs → hypothalamus → motor association cortex → motor cortex → motor organ.<br>
　　In the case of emotions which don't need a complicated analysis, such as aversion and fear, there is also a path to enter the amygdala directly from sensory receptor.<br>
　　The route for controlling actions of emotions is, sensory receptor → sensory cortex → sensory association cortex→ basal nuclei → supplementary motor cortex → motor cortex → motor organ.<br>
　　Among these the particularly important parts connected to emotions are the amygdala, hypothalamus, basal nuclei, and prefrontal cortex.<br>
<br>
Amygdala<br>
　　Amygdala is the organ for recognizing emotions.<br>
　　Amygdala has cells to handle various emotions. Cells which only respond to a favorite food were discovered in the amygdala of monkeys.<br>
　　Monkeys will escape when they see a snake. However, a monkey which has had its amygdala removed isn't afraid of snakes. On the contrary, that monkey will attempt to eat snakes. It has lost its emotions.<br>
　　Of course the amygdala has a crucial influence on human beings too. During the autopsy a tumor was found in the amygdala of the vicious criminal who killed 38 people at Texas University in United States.<br>
　<br>
Hypothalamus<br>
　　Emotions have two important elements. First is that emotions can be felt before acting. The second is that people can recognize the quantity.<br>
　　The degree that the hypothalamus acts corresponds to the emotion's quantity. Regardless of what emotion is felt, the hypothalamus expresses the quantity of the emotion currently felt.<br>
　　The rat which had an electrode inserted into its hypothalamus cells will continue to push the button which sends electricity to the electrode. Even if there are painful obstacles such as an electric shock on the road to the button, the rat will overcome those obstacles and continue to push the button without eating food until it passes out. Researchers believe this is because the rat received a strong pleasant sensation.<br>
　　Each emotion has a related chemical substance. Interest is related to dopamine, love is related to oxytocin, anger is related to testosterone, fear is related to serotonin. The quantity of these chemicals is related to the quantity of the emotion.<br>
<br>
Basal nuclei<br>
　　The basal nuclei regulates the action of emotion.<br>
　　The cells which get excited according to the action accompanying an emotion were found in the basal nuclei. It controls the motor program for emotions. Pleasure and displeasure occurs there and cause the corresponding action.<br>
<br>
Prefrontal cortex<br>
　　The motor program is made in the prefrontal cortex. It is the part that makes concrete actions.<br>
　　The amygdala, hypothalamus, basal nuclei, and prefrontal cortex are the places where emotion is, but other parts are not irrelevant. Functions of the mind operate only after the circular route is completed, but the narrowest parts of this route for emotion are the amygdala, hypothalamus, basal nuclei, and prefrontal cortex.