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RIKEN Center for Brain Science Cognitive Somnology RIKEN Hakubi Research Team

RIKEN Hakubi Team Leader: Masako Tamaki (Ph.D)

Research Summary

 Masako Tamaki (Ph.D)

Why do you think and behave the way you do? For example, one day you may abruptly decide to get a cup of tea instead of coffee, or you may come up with a brilliant idea that had never occurred to you before. Accumulating behavioral evidence suggests that the sleeping brain plays a critical role in our thoughts and actions. However, little is known about the ways the sleeping brain accomplishes this work. Our team develops and integrates various neuroimaging, physiological, and psychophysical techniques to elucidate the fundamental role of the sleeping brain in human cognition and behavior.

Main Research Fields

  • Complex Systems

Related Research Fields

  • Informatics
  • Environmental Science
  • Humanities & Social Sciences
  • Humanities
  • Social Sciences
  • Interdisciplinary Science & Engineering
  • Biological Sciences
  • Medicine, Dentistry & Pharmacy
  • Experimental psychology
  • Basic / Social brain science
  • Cognitive science


  • Sleep
  • Cognition
  • Learning
  • Dreaming

Selected Publications

Papers with an asterisk(*) are based on research conducted outside of RIKEN.

  • 1. *Tamaki, M., Wang, Z., Barnes-Diana, T., Guo, D., Berard, AV., Walsh, E.G., Watanabe, T., and Sasaki, Y.:
    "Complementary contributions of NREM and REM sleep to visual learning"
    Nature Neuroscience 23, 1150-1156. (2020).
  • 2. *(†Co-first author) †Tamaki, M., †Berard, A.V., Barnes-Diana, T., Siegel, J., Watanabe, T., and Sasaki, Y.:
    "Reward does not facilitate visual perceptual learning until sleep occurs"
    Proceedings of the National Academy of Sciences of the United States of America 117, 959-968. (2020.
  • 3. *Tamaki, M., Wang, Z., Watanabe, T., and Sasaki, Y.:
    "Trained-feature-specific offline learning by sleep in an orientation detection task"
    Journal of Vision 19, 1-14. (2019).
  • 4. *Tamaki, M., and Sasaki, Y.:
    "Surveillance during REM sleep for the first-night effect"
    Frontiers in Neuroscience 13:1161. (2019).
  • 5. *Shibata, K., Sasaki, Y., Bang, J.W., Walsh, E.G., Machizawa, M.G., Tamaki, M., Chang, Li-Hung., and Watanabe, T.:
    "Overlearning hyperstabilizes a skill by rapidly making neurochemical processing inhibitory-dominant"
    Nature Neuroscience 20, 470-475. (2017).
  • 6. *Tamaki, M., Bang, J.W., Watanabe, T., and Sasaki, Y.:
    "Night watch in one brain hemisphere during sleep associated with the first-night effect in humans"
    Current Biology 26, 1190-1194. (2016).
  • 7. *Tamaki, M., Bang, J.W., Watanabe, T., and Sasaki, Y.:
    "The first-night effect suppresses the strength of slow- wave activity originating in the visual areas during sleep"
    Vision Research 99, 154-161. (2014).
  • 8. *Tamaki, M., Huang, T.R., Yotsumoto, Y., Hämäläinen, M., Lin, F.H., Náñez, J.E. Sr., Watanabe, T., and Sasaki, Y.:
    "Enhanced spontaneous oscillations in the supplementary motor area are associated with sleep-dependent offline learning of finger-tapping motor-sequence task"
    Journal of Neuroscience 33, 13894-13902. (2013).
  • 9. *Horikawa, T., Tamaki, M., Miyawaki, Y., Kamitani, Y.:
    "Neural decoding of visual imagery during sleep"
    Science 340, 639-642. (2013).

Recent Research Results

Related Links

Lab Members

Principal investigator

Masako Tamaki
RIKEN Hakubi Team Leader


Position Deadline
Seeking a Postdoctoral Researcher (W24064) Open until filled
Seeking a Postdoctoral Researcher or Research Scientist (W23057) Open until filled

Contact Information

Center for Brain Science Central Building
2-1 Hirosawa, Wako, Saitama 351-0198, Japan
Email: masako.tamaki [at] riken.jp