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Identification of Happy Center in the Brain
SU Jingyang (KUWAKI Tomoyuki)

We have successfully identified the brain region from where happy emotions arise by examining cataplexy attacks. Cataplexy is one of the characteristics of narcolepsy (one of the sleep disorders) and is triggered mainly by happy emotions such as laughter in humans and palatable food in mice. Cataplexy cannot be controlled by volition and thus might be a better behavioral measure of happy emotion than observing approaching behavior which may be triggered by both emotion and intellect. Using orexin neuron-ablated mice, one of the animal models of narcolepsy, we identified the Nucleus Accumbens (NAc) as the active brain region that is closely related to the initiation of cataplexy attack. This result indicates that the NAc is a source of happy emotion. To confirm our hypothesis, we activate or inactivate the NAc by artificial method using AAV-Gq and AAV-Gi. As expected, activation and inactivation of the NAc resulted in an increase and decrease of cataplexy attack, respectively. This study opens a new road to study how happy emotion affects physical well-being.

Involvement of the Nucleus Accumbens in Chocolate-induced Cataplexy. Su J, Li Z, Yamashita A, Kusumoto-Yoshida I, Isomichi T, Hao L, Kuwaki T. Scientific Reports 10:4958, 2020.

<Figure Legends>
A) Procedure to take brain samples after the mouse* bite chocolate. Upper: No cataplexy control. Middle: After the recovery from cataplexy. Lower: Just after the start of cataplexy.
B) Side view of the mouse's brain. Coronal section at the vertical line was shown in the lower panel. Red area indicates drug spread in the Nucleus Accumbens (NAc).
C) Artificial activation of the NAc (using AAV-Gq + CNO) increased the number of cataplexy bouts and inactivation (with AAV-Gi + CNO) decreased them.
*We used orexin neuron-ablated mice as the model animal of narcolepsy/cataplexy.

Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Japan