PAM+/− (Total N=29; N per group=6-8) and WT mice (Total N =22; N per group=5-6) on the indicated diet were placed in the elevated zero maze for 5 min; the amount of time spent in the open areas was assessed by a blinded observer and is expressed as a percentage of the total time in the maze. Copper deficient WT mice spent less time in the open areas than WT mice on the control diet (two-way deficiency main effect p=0.025; independent t-test, p=0.004). On the control diet, PAM+/− mice spent less time in the open arms than WT mice (two-way genotype main effect p=0.008; independent t-test, p=0.001), suggesting an anxiety-like phenotype. While PAM+/− mice demonstrated a lower behavioral sensitivity to copper deficiency compared to WT mice (two-way interaction, p=0.001), PAM+/− mice fed the copper supplemented diet spent more time in the open areas than PAM+/− mice on the control diet (independent t-test, p=0.002). The behavior of WT mice did not change significantly with copper supplementation (two-way interaction p=0.005). Error bars, SEM.