GRIN2B and schizophrenia: However, in contrast with previous studies that have revealed that NR2B antagonists produce hyperlocomotor activity in rodents (Chaperon et al., 2003; Mathur et al., 2009), the present study revealed that a single knockdown of the NR2B subunit in the hippocampus did not induce hyperlocomotion in mice, possibly indicating that the hippocampal-restricted deletion of NR2B could not induce the positive symptoms of schizophrenia in mice.