1Institute of Biomedicine, Physiology, University of Helsinki, Helsinki 00014, Finland,
2Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom,
3Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan,
4Division of Cerebral Integration, National Institute for Physiological Sciences, Okazaki 444-8585, Japan,