Compared with WT mice, Npas2 null mutant mice exhibited reduced anxiety-like behavior as seen by the increased percent time spent in the open arms of the elevated plus maze (Figure 1A, Mann-Whitney test, Npas2 null mutant median = 7.75, n = 24, WT mean = 2.09, n = 16, U = 115, p = 0.032). This evidence concerns the gene NPAS2 and Anxiety.