SLC6A4 and Anxiety: Baseline assessment of innate anxiety-associated behaviors revealed that, compared to both wildtype SERT+/+ rats (n = 8) and SERT+/− rats (n = 13), only SERT−/− rats (n = 11) displayed reduced time spent: (1) in the light box (F(2,29) = 5.7, p = 0.008, Fig. 1c); (2) in the center zone of open field (F(2,29) = 4.0, p = 0.029, Fig. 1d); or in the open arm + transition zone of the elevated plus maze (F(2,29) = 4.5, p = 0.019, Fig. 1e).