Fig. 7: Mechanism 1 can account for optimistic biases in reward-seeking behavior and cue-evoked dopamine responses. | Nature Communications

Fig. 7: Mechanism 1 can account for optimistic biases in reward-seeking behavior and cue-evoked dopamine responses.

From: Tonic dopamine and biases in value learning linked through a biologically inspired reinforcement learning model

Fig. 7

a Schematic of the analysis. This figure shows the last three stages. b Schematic shows model predictions of dopamine concentrations and receptor occupancies for control (black) and lesion (red) groups. The arrows depict the increase or decrease in occupancy for a fixed positive or negative dopamine transient. c Model predicted changes in receptor occupancy as a function of dopamine transients (mean ± s.e.m., n = 45 control, n = 44 lesion). The slope for positive and negative domains corresponds to D1R and D2R sensitivities, respectively. d Asymmetric scaling factors derived from receptors’ sensitivities (n = 45 control, n = 44 lesion) are increased in the lesion group (U = − 7.707, P < 1.0 × 10−15, single-sided M-W test). e Risk-sensitive TD model trained on these receptor sensitivities predicts a higher baseline value for the lesion group’s derived parameters (t-statistic = − 6.484, P < 1.0 × 10−7, two-sided t test). f The same risk-sensitive TD learning model predicts increases in value predictions for all cues (t = − 5.761, P < 1.0 × 10−6, t = − 6.433, P < 1.0 × 10−7, t = − 6.282, P < 1.0 × 10−6, two-sided t test, for 10%, 50% and 90% cues, mean ± s.e.m, n = 45 control, n = 44 lesion) and an optimistic bias in normalized value prediction to the 50% cue (t-statistic − 6.444, P < 1.0 × 10−7, two -sided t test). g The same risk-sensitive TD learning model predicts lower cue responses in lesioned animals (mean ± s.e.m. n = 45 control, n = 44 lesion, U = 4.844, P < 1.0 × 10−5, U = – 3.658, P = 0.00025, U = 4.734, P < 1.0 × 10−4, two -sided M-W test for 10%, 50% and 90% cues). Normalized TD errors for the 50% cue show an optimistic bias (t = – 6.508, P < 1.0 × 10−7, two-sided t test). The centre of the box plot shows the median; edges are the 25th and 75th percentiles; whiskers are the most extreme data points not considered as outliers. M-W test, Mann-Whitney U-test; U, U-statistic; t, t-statistic. Source data provided in ‘source_data/figure_7’.

Back to article page