Figure 8.

Effect of striatal circuit on sustained responses of model dopamine neurons. The black line shows the percentage sustained change in the dopamine activity as percentage above baseline as simulated by the complete model (same as Fig. 6), and gray lines indicate the percentage sustained change in the activity as simulated with selected elements of the striatal circuit (TANs and FS interneurons) excluded. Both simulations are performed with the same reward magnitude (|R*| = 0.15) and with the same parameter set. Although the qualitative behavior of the model is similar in both cases (inverted-U-shaped elevations in sustained responses as a function of conditional probability of reward), inclusion of the interneurons of the striatal circuit enhances the contrast between the responses to different probabilistic schedules.