Article Figures & Data
Figures
- Figure 1.
Conditioned approach behavior throughout acquisition and postasymptotic training. A, Probability to lever press by training session. B–D, Probability to lever press (B), total lever presses (C), and latency to lever press (D) binned by decades of trials. The green line depicts the best fit from the Weibull function for each behavioral measure. Vertical dotted lines denote the decade in training where asymptotic performance was reached, as determined by the best fit parameter from the Weibull function. Data are mean ± SEM.
- Figure 2.
Dopamine dynamics during preasymptotic and postasymptotic pavlovian conditioning. A, All recording sites (●) were within the nucleus accumbens core. The numbers on each plate indicate the distance in millimeters anterior from bregma (Paxinos and Watson, 2005). B, Average peak CS- and US-evoked dopamine release across 375 trials of conditioning. C, Color-coded observed changes in electrochemical information as a function of applied potential (y-axis) plotted over time (x-axis). D, Comparison of peak US-evoked and CS-evoked phasic dopamine release at different points in training. E, Reward-evoked dopamine release before the start of each training session. Reward-evoked dopamine release did not significantly change over sessions as determined by one-way repeated-measures ANOVA (F(14,126) = 0.79, p > 0.05; post-test for linear trend, p > 0.05). F, Color-coded observed changes in electrochemical information as a function of applied potential (y-axis) plotted over time (x-axis). Gray triangles denote CS onset or reward delivery. Data are mean ± SEM. ***p < 0.001. ns, Not a statistically significant difference.
- Figure 3.
Effect of temporal expectation on stimulus-evoked dopamine release. A, Illustration of task design (left) and US-evoked dopamine during test sessions (middle) relative to preconditioning level (right). B, Experienced cumulative probability of CS presentation during sessions 5 and 15 (left), CS-evoked dopamine as a function of ITI length (middle), and comparison of short to long ITIs at postacquisition asymptote and after extended training (right). C, Illustration of task design (left) and CS-evoked dopamine during the probe session (middle) relative to peak levels at postacquisition asymptote (right). Data are mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.005.
- Figure 4.
Temporal dynamics of CS-evoked dopamine and dopamine dependence of conditioned behavior. A, Normalization of conditioned approach behavior and CS-evoked dopamine across all phases of training. B, Conditioned approach behavior on a test session after injection of SCH23390 or saline in animals that received either 5 sessions (saline: n = 6; SCH23390: n = 8; blue) or 15 sessions (saline: n = 7; SCH23390: n = 5; red) of training. Shaded blocks in A correspond to the point in training where pharmacological experiments were conducted in B. The vertical dotted line denotes the decade in training where asymptotic performance was reached. Data are mean ± SEM. *p < 0.05, ***p < 0.005.
