Atsushi Iriki, DDS, PhD, DMSc.Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Japan Hirotaka J. Okano, MD, PhD.Laboratory of Regenerative Medicine, The Jikei University School of Medicine, Japan Erika Sasaki, PhD.Department of Applied Developmental Biology, Central Institute for Experimental Animals, Japan Hideyuki Okano, MD, PhD.Department of Physiology, Keio University School of Medicine, Japan