1. Department of Behavioral and Brain Sciences, Primate Research Institute, Kyoto University, Inuyama, 484-8506;
2. Department of Nuclear Medicine and Radiology, IDAC, Tohoku University, Sendai, 980-8575;
3. Department of Biofunctional Research, National Institute for Longevity Sciences, Obu, 474; and
4. Department of Social and Information Sciences, Nihon Fukushi University, Handa, 475, Japan