Decreased locomotor activity in HbSS mice in the open field test. The open field test was used to measure locomotor activity and anxiety. Animal movement over a 20-minute period was recorded. (A) HbSS traveled 706 ± 37 cm (n = 9) compared to HbAA controls that traveled 2081 ± 123 cm (n = 10), a 2.9-fold decrease (**P <0.01). (B) Time spent in the center zone averaged 191 ± 26 sec compared to HbAA controls that traveled 88 ± 23 sec. (C) Both genotypes exhibited a similar frequency of entries into the center zone. Genotypes were compared using a two-way ANOVA with Bonferroni’s post-hoc analysis (A) and student’s t-tests (B, C). Error bars indicate S.E.M.