Pharmacological Dopamine Manipulation Does Not Alter Reward-Based Improvements in Memory Retention during a Visuomotor Adaptation Task

Task and paradigm. A, Task. Participants made 6 cm reaching movements to a target. Visual feedback was perturbed by a 40° clockwise rotation (R) in adaptation phase (rotation). In no vision trials, the cursor and the hand position corresponded but there was no visual feedback. B, Study protocol. Participants completed 72 trials of baseline training with veridical visual feedback, followed by 72 baseline trails with no visual feedback (no vision). Drug (LD/haloperidol/placebo) was then administered and participants waited the corresponding waiting time (1 h for LD or placebo, 2 h for haloperidol). After that, the two baseline blocks were repeated (baseline 2). During adaptation, visual feedback was perturbed 40° clockwise for 216 trials (three blocks). To avoid this starting abruptly at the beginning of a block, the first adaptation block started with six baseline trials with veridical visual feedback, followed by 72 trials with the perturbation. Then, participants were exposed to 216 (retention, three blocks) trials with no perturbation and no visual feedback. Again, to avoid a context change at the beginning of a block, the last adaptation block finished with six retention trials (i.e., total 78 trials in last adaptation block, followed by two retention blocks of 72 trials and one block of 66 trials). C, Hand trajectories toward each target of one representative subject in the R-Pl (violet) and punish-placebo (blue) group. From left to right, Last trial toward each target of baseline 1, last trial toward each target of adaptation, last trial toward each target of retention.