Figure 6.

(A-C) The changes in TAN pause (TP) duration by three different factors: the duration of thalamic stimulation, the percentage of dopamine (DA) deficiency, the L-DOPA level in 50% DA deficiency condition when RPE (Reward Prediction Error) = 1 (phasic, reward), 0 (tonic baseline), and −1 (phasic, aversive), respectively. (A) The changes in TP duration by the duration times of thalamic stimulation. The increment of thalamic stimulation duration increases TP duration for all RPE values. The difference of TP duration between RPE = 1 and RPE = −1 keeps increasing nonlinearly as increases in thalamic stimulation duration. (B) The changes in TP duration by the percentages of DA deficiency. The increased percentage of DA deficiency decreases TP duration when RPE = 1 and 0. For RPE = −1, the TP duration is nearly independent of the amount of DA deficiency, which is the result of RPE = −1 corresponding to the minimum possible DA concentration during the TP. Therefore, the TP duration for RPE = −1 is unaffected by the degradation of dopaminergic inputs. The deviation difference of TP duration from RPE = 0 between RPE = 1 and RPE = −1 keeps decreasing nonlinearly as increases in percentage of DA deficiency, which means minimizing the time difference between reward and aversive conditions for reinforcement learning and in turn deteriorating the learning performance. (C) The changes in TP duration by the levels of L-DOPA in 50% DA deficiency condition. In response to the administration of L-DOPA, the TP duration increases similarly for all RPE values. This follows from the fact that L-DOPA alters the baseline concentration of dopamine, but does not affect the phasic dopamine release.