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

Abstract

Motor adaptation tasks investigate our ability to adjust motor behaviors to an ever-changing and unpredictable world. Previous work has shown that punishment-based feedback delivered during a visuomotor adaptation task enhances error-reduction, whereas reward increases memory retention. While the neural underpinnings of the influence of punishment on the adaptation phase remain unclear, reward has been hypothesized to increase retention through dopaminergic mechanisms. We directly tested this hypothesis through pharmacological manipulation of the dopaminergic system. A total of 96 young healthy human participants were tested in a placebo-controlled double-blind between-subjects design in which they adapted to a 40° visuomotor rotation under reward or punishment conditions. We confirmed previous evidence that reward enhances retention, but the dopamine (DA) precursor levodopa (LD) or the DA antagonist haloperidol failed to influence performance. We reason that such a negative result could be due to experimental limitations or it may suggest that the effect of reward on motor memory retention is not driven by dopaminergic processes. This provides further insight regarding the role of motivational feedback in optimizing motor learning, and the basis for further decomposing the effect of reward on the subprocesses known to underlie motor adaptation paradigms.

Domain-specific working memory, but not dopamine-related genetic variability, shapes reward-based motor learning

“…However, given the informative and coherent relationships between WM and motor learning and the ability to predict overall performance on that basis, could it be that the genes we selected do not relate in any meaningful way to performance in these reward-based tasks? In line with this, a recent study showed that DA pharmacological manipulation did not alter reward effects in a visuomotor adaptation task (Quattrocchi et al, 2018). However, previous work has shown that Parkinson’s disease patients show impaired reward-based motor performance (Pekny et al, 2015).…”

Rewards interact with repetition‐dependent learning to enhance long‐term retention of motor memories

“…This finding is likely to be attributable to the gradual nature of the perturbation schedule, which largely controlled and dictated rates of learning . Despite this consideration, such a lack of effect nonetheless remains challenging to put in perspective with the literature, since mixed patterns of results regarding rewards’ influence on motor learning have been reported . For instance, while some studies have shown that rewards leave acquisition unaltered but facilitate immediate retention, others have conversely shown that rewards facilitate acquisition but leave immediate retention unaltered .…”

“…Despite this consideration, such a lack of effect nonetheless remains challenging to put in perspective with the literature, since mixed patterns of results regarding rewards’ influence on motor learning have been reported . For instance, while some studies have shown that rewards leave acquisition unaltered but facilitate immediate retention, others have conversely shown that rewards facilitate acquisition but leave immediate retention unaltered . A recent report even revealed that rewards can be detrimental to acquisition of novel motor behaviors by interfering with explicit learning processes, which adds to the apparent complexity of the way rewards influence acquisition.…”

“…Given work in animals and humans suggesting that retention may benefit from maximizing reward availability during acquisition (i.e., possibility to earn a reward on 100% of trials) or from limiting it (i.e., possibility to earn a reward on 50% of trials), the present design used three levels of reward availability: “0%,” 50%, or 100%. Although rewards were never explicitly delivered in the “0%” condition, the use of quotation marks is to acknowledge the possibility that target hits, in themselves, could have been experienced as intrinsic rewards, which are known to influence long‐term retention .…”

“…), ultimately leading to enhanced neuroplastic changes necessary for memories to emerge . Another learning context documented to facilitate retention of motor memories consists of delivering performance‐contingent monetary rewards during acquisition of novel motor behaviors . At the neural level, this reward‐induced enhancement of retention may be mediated via dopaminergic (DAergic) signaling, believed to reinforce the neural trace associated with the behavior that led to the reward .…”