The capacity to acquire and retain new motor skills is essential for everyday behavior and a prerequisite to regain functional independence following impairments of motor function caused by brain damage, e.g., ischemic stroke. Learning a new motor skill requires repeated skill practice and passes through different online and offline learning stages that are mediated by specific dynamic interactions between distributed brain regions including the cerebellum. Motor sequence learning is an extensively studied paradigm of motor skill learning, yet the role of the cerebellum during online and offline stages remains controversial. Here, we studied patients with chronic cerebellar stroke and healthy control participants to further elucidate the role of the cerebellum during acquisition and consolidation of sequential motor skills. Motor learning was assessed by an ecologically valid explicit sequential finger tapping paradigm and retested after an interval of 8 h to assess consolidation. Compared to healthy controls, chronic cerebellar stroke patients displayed significantly lower motor sequence performance independent of whether the ipsilesional or contralesional hand was used for task execution. However, the ability to improve performance during training (i.e., online learning) and to consolidate training-induced skill formation was similar in patients and controls. Findings point to an essential role of the cerebellum in motor sequence production that cannot be compensated, while its role in online and offline motor sequence learning seems to be either negligible or amenable to compensatory mechanisms. This further suggests that residual functional impairments caused by cerebellar stroke may be mitigated even months later by additional skill training.
Keywords: Cerebellum; Motor consolidation; Motor control; Motor learning; Stroke.