1. Department of Physiology, School of Medicine, Yamagata University, 2‐2‐2 lida Nishi, Yamagata 990‐23, Japan
2. Department of Psychology, The University of North Carolina at Greensboro, Greensboro, NC, USA
3. Neural Plasticity and Regeneration Group, Institute for Biological Sciences, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6