Figure 2. Task performance after AMPH injection.

(A) Change of median running velocity after injection of AMPH with respect to values before injection. (B) Mean change in the relative proportion of trials with off-task behavior. (C) Change in the median time of occupancy at the start feeder. (D) Representative examples of running path superimposed for all trials in one session before (blue) or after (red) injection of vehicle or AMPH. (E) Mean change in running path roughness of all rats for the task epoch from the target feeders back to the start feeder. (F) Change in roughness of running path from the start feeder to target feeders, as measured by mean change in Hausdorff fractal dimension for all rats. Error bars show the Standard Error of the Mean (SEM) or Median (SEMd). Here and following figures: asterisks (*) indicate statistically significant differences at α = 0.05 with Bonferroni correction; only comparisons with saline are illustrated.

Figure 2—figure supplement 1. Time at target feeders decreases after AMPH.

(A) Post-injection change in median time at target feeders when given the large reward volume, with respect to the time at feeders for large reward prior to drug. Data show mean and standard error of the mean for the session-wise median for all animals, which significantly reduce as AMPH increases (ANOVA, F_3,62 = 3.93, p=0.012). (B) The change in feeder dwell times during small reward after AMPH relative to baseline, computed over all sessions. Time tends to reduce as AMPH increases, but this is not statistically significant because of the large variance at 0.5 mg/kg. (C) Median time spent at feeders after injection for all sessions. Plot shows median and standard error of the median for each session-wise median value. Rats spent less time at feeders during small rewards as compared to large after every dose (Kruskal-Wallis within each dose, α <0.05 after Bonferroni correction).