Fig. 1.

Subthalamic nucleus connectivity and model based versus model free learning. The two-step model-based model-free learning task is depicted on the left. A stimulus chosen at stage 1 (S1) led with 70/30% probability to one of two states (pink or blue in the schematic image) at stage 2 (S2). Choice of a stimulus at S2 led, with varying probability, to reward or no reward. Subthalamic nucleus (STN) connectivity with whole brain was computed and correlated with w, the relative contribution of model-free (w = 0) or model-based (w = 1) learning tendencies derived from the task. The y axis represents the functional connectivity between STN and a given region, and the x axis is the behavioural measure of w (top) or perseveration (bottom). STN connectivity with VS and mOFC positively correlated with w (top) and STN connectivity with premotor cortex and insula negatively correlated with perseveration (bottom). Displayed at p < .005 whole brain uncorrected for illustration on standard MNI template.