The effect of reward on motor adaptation and motor control

The prospect for rewarding outcomes has long been known for its impact on human behaviour, and motor control is no exception to this. Recent years were marked by widespread interest in how reward alters motor learning and motor control in humans, and subsequent efforts produced a wealth of descriptive reports underlining which behaviours are shaped by it. More recently, the focus is shifting toward asking which underlying mechanisms drive these alterations and this work adheres to this effort. This thesis is divided into two main parts. First, investigating what underlying mechanisms drive enhancement of motor learning with reward, we see that explicit control is tightly coupled with reward processing in motor adaptation. Extending these findings, we explore which individual characteristics predict sensitivity to reward during motor learning, and observe that working memory, rather than genetic profile, shapes this variability. In the second part, we turn to motor control, and see that enhanced control during reaching is driven by regulation of arm stiffness, in addition to other proposed mechanisms such as feedback control. Finally, in an attempt to manipulate reward-based effects using transcranial magnetic stimulation of the ventromedial prefrontal cortex and supplementary motor area, no alteration of behavioural enhancements was observed