Reward-based improvements of motor performance in health and disease

Abstract

Reward has been found to boost motor performance and improve learning in both healthy individuals and in clinical populations. The aim of this thesis was to gain a better understanding of how reward affects different specific aspects of motor performance and learning across various age and health status groups. This work provides an important step towards optimising the use of reward within clinical populations such as stroke patients. The introductory chapter (Chapter 1) provides a comprehensive review of relevant literature, setting the stage for the investigations that follow. As motor performance and reward responsiveness tend to decline with age, Chapter 2 investigated the age- related differences in reward-based improvement in motor performance. We observed that both young and older adults showed improved performance with rewards, but the young group exhibited significantly higher reward-based enhancement in motor performance. In chapter 3, we extended these results by examining how reward impacts motor performance in stroke patients. In this study, we also investigated the impact of rehabilitation on reward sensitivity. Our findings suggest that stroke patients' motor performance significantly improved with the presence of reward. We also found that patients' performance improved after rehabilitation, but there were no changes in reward sensitivity. Chapter 4 investigated the role of the primary motor cortex within the reward-based enhancement of motor performance using repetitive transcranial magnetic stimulation. No effects on performance were observed. In Chapter 5 of this thesis, we explored how reward affects sequential movements and how manipulating task difficulty can impact reward-based improvement in sequential movement fusion. Our findings suggest that sequential movement fusion is more effective when the task is easy, and this effect is further enhanced by the presence of a reward. The thesis concludes with Chapter 6, which synthesizes the findings, discusses their implications, and proposes directions for future research. This study not only advances our understanding of reward-based motor learning but also provides a foundation for optimizing reward utilization in clinical settings, offering hope for improved rehabilitation strategies.