1. Department of Cognitive, Linguistic, and Psychological Sciences, Box 1853, Brown University, Providence, RI 02912, USA.
2. Department of Neuroscience, Brown University, Providence, RI 02912 USA.
3. Bio-navigation Research Center, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan.
4. Institute of Cybernetics, 5 S. Euli, 0186, Tbilisi, Georgia.