Figure 1. Cohort 1. Initial dose-response curves were conducted to determine the optimal dose of amphetamine for inducing hyperactivity in BTBR and B6 in a novel open field. Amphetamine elevated parameters of exploratory locomotion in both strains.

Parameters of total distance traversed, horizontal activity, vertical activity and time spent in the center of the arena were measured across a 30 minute test session in an Accuscan open field in BTBR and B6, following an intraperitoneal injection of amphetamine (AMPH) at doses of 1.0 mg/kg, 2.0 mg/kg, 3.0 mg/kg, or saline vehicle (0.0). Data are shown in 5 minute time bins. B6 displayed significant increases in (A) total distance traversed and (C) horizontal activity following AMPH administration at doses of 2.0 and 3.0 mg/kg, as compared to saline vehicle. (E) Vertical activity in B6 was reduced by AMPH at each dose tested. BTBR displayed significant increases in (B) total distance traversed and (D) horizontal activity following AMPH administration at each dose. (F) Vertical activity in BTBR was not significantly affected by AMPH administration. Time spent in the center of the arena did not differ in B6 (G) or BTBR (H) treated with any dose of AMPH compared to vehicle. For all figures, data are shown as mean ± standard error of the mean (SEM). *p < 0.05 as compared to vehicle. N=10 per strain per dose in Cohort 1. See Supplementary Material for the similar open field results in Cohorts 2 and 3.