1: Dysfunction of ventrolateral striatal dopamine receptor type 2-expressing medium spiny neurons impairs instrumental motivation.
Science of the Month - March 2017
Nature Communications
2017 Feb 1;8:14304. doi: 10.1038/ncomms14304.
Iku Tsutsui-Kimura, Hiroyuki Takiue, Keitaro Yoshida, Ming Xu, Ryutaro Yano, Hiroyuki Ohta, Hiroshi Nishida, Youcef Bouchekioua, Hideyuki Okano, Motokazu Uchigashima, Masahiko Watanabe, Norio Takata, Michael R. Drew, Hiromi Sano, Masaru Mimura & Kenji F. Tanaka
Motivation is generated by the brain. Therefore, it is natural that if the brain is damaged, one's ability to act with motivation is lost. So, where in the brain and to what extent must damage occur for motivation to decrease? This study began with this very question. The conclusion is that when just nearly 20% of the D2-MSN cell population in the ventrolateral striatum of the basal ganglia is impaired, motivational behavior decreases. In fact, this conclusion overturned the existing dogma. This is because it was previously thought that impairment of D2-MSNs would lead to motivated drug-seeking behavior; in other words, that D2-MSNs acted as a brake. If you think of motivation as an accelerator, this is the complete opposite. For this reason, we were required to make our results more robust by using three advanced techniques: a genetic modification technique to ablate D2-MSNs at a desired time, a technique called optogenetics to suppress cell function with light, and a further application of optogenetics to ablate cells with light. We explained the difference in results by the difference in rewards (drugs vs. palatable food) and the difference in the location of D2-MSNs, but the difference between normal and pathological motivation remains a topic for future research. The above is the result of the Endowed Chair for Research in the Control and Treatment of Affective Disorders, Department of Neuropsychiatry, which started in 2012, and the entire lab worked together to achieve this result.
(Kenji Tanaka, Department of Neuropsychiatry, Class of '76)
Other Published Papers
1: Comparison of Targeted vs Random Biopsies for Surveillance of Ulcerative Colitis-Associated Colorectal Cancer
GASTROENTEROLOGY
151 (6):1122-1130; 10.1053/j.gastro.2016.08.002 DEC 2016
Watanabe Toshiaki, Ajioka Yoichi, Mitsuyama Keiichi, Watanabe Kenji, Hanai Hiroyuki, Nakase Hiroshi, Kunisaki Reiko, Matsuda Keiji, Iwakiri Ryuichi, Hida Nobuyuki, Tanaka Shinji, Takeuchi Yoshiaki, Ohtsuka Kazuo, Murakami Kazunari, Kobayashi Kiyonori, Iwao Yasushi, Nagahori Masakazu, Iizuka Bunei, Hata Keisuke, Igarashi Masahiro, Hirata Ichiro, Kudo Shin-ei, Matsumoto Takayuki, Ueno Fumiaki, Watanabe Gen, Ikegami Masahiro, Ito Yoko, Oba Koji, Inoue Eisuke, Tomotsugu Naoki, Takebayashi Toru, Sugihara Kenichi, Suzuki Yasuo, Watanabe Mamoru, Hibi Toshifumi
2: Norepinephrine Transporter in Major Depressive Disorder: A PET Study
AMERICAN JOURNAL OF PSYCHIATRY
174 (1):36-41; 10.1176/appi.ajp.2016.15101334 JAN 2017
Moriguchi Sho, Yamada Makiko, Takano Harumasa, Nagashima Tomohisa, Takahata Keisuke, Yokokawa Keita, Ito Takehito, Ishii Tatsuya, Kimura Yasuyuki, Zhang Ming-Rong, Mimura Masaru, Suhara Tetsuya