1. Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
2. Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 100-0004, Japan
3. Research Center for Language, Brain and Genetics, Tokyo Metropolitan University, Hachioji, Tokyo 192-037, Japan
4. Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
5. Laboratory for Language Development, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan