Center for Movement Studies, Kennedy Krieger Institute, 707 North Broadway, Room G-04, Baltimore, MD, 21205, USA.
Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA.
Cerebellum. 2018 Apr;17(2):111-121. doi: 10.1007/s12311-017-0879-0.
The cerebellum is thought to adapt movements to changes in the environment in order to update an implicit understanding of the association between our motor commands and their sensory consequences. This trial-by-trial motor recalibration in response to external perturbations is frequently impaired in people with cerebellar damage. In healthy people, adaptation to motor perturbations is also known to induce a form of sensory perceptual recalibration. For instance, hand-reaching adaptation tasks produce transient changes in the sense of hand position, and walking adaptation tasks can lead to changes in perceived leg speed. Though such motor adaptation tasks are heavily dependent on the cerebellum, it is not yet understood how the cerebellum is associated with these accompanying sensory recalibration processes. Here we asked if the cerebellum is required for the recalibration of leg-speed perception that normally occurs alongside locomotor adaptation, as well as how ataxia severity is related to sensorimotor recalibration deficits in patients with cerebellar damage. Cerebellar patients performed a speed-matching task to assess perception of leg speed before and after walking on a split-belt treadmill, which has two belts driving each leg at a different speed. Healthy participants update their perception of leg speed following split-belt walking such that the "fast" leg during adaptation feels slower afterwards, whereas cerebellar patients have significant deficits in this sensory perceptual recalibration. Furthermore, our analysis demonstrates that ataxia severity is a crucial factor for both the sensory and motor adaptation impairments that affect patients with cerebellar damage.
小脑被认为可以根据环境变化调整运动，从而更新我们的运动指令与其感官后果之间的隐性理解。在小脑受损的人群中，这种针对外部干扰的逐次运动重新校准通常会受到损害。在健康人群中，也已知适应运动干扰会引起一种感觉知觉重新校准。例如，伸手适应任务会产生手位置感觉的短暂变化，而行走适应任务会导致感知腿部速度的变化。尽管这些运动适应任务严重依赖于小脑，但尚不清楚小脑与这些伴随的感觉重新校准过程有何关联。在这里，我们想知道小脑是否参与了伴随步行适应而发生的腿部速度知觉的重新校准，以及小脑损伤患者的共济失调严重程度与感觉运动重新校准缺陷之间的关系。小脑患者在分裂带跑步机上行走前后进行速度匹配任务，以评估腿部速度的感知。分裂带跑步机的两条带子分别以不同的速度驱动每条腿。健康参与者在分裂带行走后会更新他们对腿部速度的感知，使得适应过程中的“快腿”之后感觉更慢，而小脑患者在这种感觉知觉重新校准方面存在显著缺陷。此外，我们的分析表明，共济失调严重程度是影响小脑损伤患者的感觉和运动适应损伤的关键因素。
