Abstract
Motor skill learning involves a complex process of generating novel movement patterns typically guided by evaluative feedback such as reward. Many studies have suggested that two separate circuits in the basal ganglia, rostral and caudal, are implicated in early goal-directed and later automatic stages of motor skill learning, respectively. However, there remains much to be elucidated about the respective involvement of the basal ganglia circuits in learning motor skills from scratch, which requires learning arbitrary action-outcome associations. To investigate this issue, we conducted a novel human fMRI experiment in which the participants learned to control a computer cursor on a screen by manipulating their right fingers. The experiment consisted of two fMRI sessions separated by five behavioral training sessions over multiple days. We discovered a double dissociation of fMRI activities in the rostral and caudal caudate nucleus, which were associated with skill performance in the early and late stages of learning. Moreover, we found that cognitive and sensorimotor cortico-caudate interactions distinctively predicted individual learning performance. In line with recent non-human primate studies, our results support the existence of parallel cortico-caudate networks involved in goal-directed and automatic stages of de novo motor skill learning.
