Some behaviours were specifically regulated by protein sequence in GluN2B CTD and others by GluN2A: GluN2A CTD regulated locomotor activity and impulsivity and GluN2B CTD regulated perceptual learning, anxiety, impulsivity and motor coordination, which must have arisen as a result of protein diversification after the duplication event approximately 550 Ma. This evidence concerns the gene GRIN2A and Anxiety.