Summary of effects on performance, beta power, and FRPs at full dose of MPTP. For both monkeys, cognitive control remains strongly represented in behavioural and delay beta oscillatory measures, in BL, and after full-dose MPTP. By contrast, FRPs show a significantly diminished or absent cognitive control effect at full dose. In each case, the difference measure is shown, and across the measures a zero difference is aligned, to provide an illustrative comparison. Behaviour: difference between non-optimal choice proportion for high- and low-control. Beta: difference in raw power between high- and low-control trials. FRP: peak z-scored Laplacian difference potential between INC and COR trials.