1. Department of Comparative and Behavioral Medicine; Faculty of Veterinary Medicine; Nippon Veterinary and Life Science University; Tokyo 180-8602 Japan
2. Integrated Brain Function Project; Tokyo Metropolitan Institute of Medical Science; Tokyo 156-8506 Japan
3. Department of Physiology; Nara Medical University; Nara 634-8521 Japan
4. Department of Biology; Faculty of Science, Toho University; Chiba 274-8510 Japan
5. Department of Anatomy; Graduate School of Medicine, Teikyo University; Tokyo 173-8605 Japan
6. Department of Biology; Faculty of Education and Integrated Sciences; Waseda University; Tokyo 169-8050 Japan