About the Authors

Wenhua Han

Affiliation Research Project for Addictive Substances, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan

Yukio Takamatsu

Affiliation Research Project for Addictive Substances, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan

Hideko Yamamoto

Affiliation Research Project for Addictive Substances, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan

Shinya Kasai

Affiliation Research Project for Addictive Substances, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan

Shogo Endo

Affiliation Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan

Tomoaki Shirao

Affiliation Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Japan

Nobuhiko Kojima

nkojima@med.gunma-u.ac.jp

Affiliations Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan, Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Japan, Laboratory for Neurobiology of Emotion, RIKEN Brain Science Institute, Wako, Japan

Kazutaka Ikeda

Affiliation Research Project for Addictive Substances, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: NK KI. Performed the experiments: WH YT HY SK NK. Analyzed the data: WH YT KI. Contributed reagents/materials/analysis tools: SE TS NK KI. Wrote the paper: WH NK KI.