Working memory load‐dependent activation levels (beta estimates) in Parkinson disease (PD) off medication (PD_OFF), PD on medication (PD_ON), and healthy controls (HC). Error bars represent standard error of the mean, with p‐values derived from 1‐way analysis of variance, Bonferroni corrected. *p < 0.05, HC compared with PD_OFF, and PD_OFF compared with PD_ON. **p < 0.001, HC compared with PD_OFF, and PD_OFF compared with PD_ON. +p < 0.05 PD_OFF compared with PD_ON. ∧p < 0.05 HC compared with PD_OFF, and HC compared with PD_ON. AIC = anterior–dorsal insula; DLPFC = dorsolateral prefrontal cortex; HPC = hippocampus; L = left; PIC = posterior insula; PUT = putamen; R = right. [Color figure can be viewed in the online issue, which is available at www.annalsofneurology.org.]