Dovern Anna, Fink Gereon R, Timpert David C, Saliger Jochen, Karbe Hans, Weiss Peter H, Koch Iring
University Hospital Cologne.
Research Centre Jülich.
J Cogn Neurosci. 2016 Feb;28(2):223-36. doi: 10.1162/jocn_a_00890. Epub 2015 Oct 6.
During rehabilitation after stroke motor sequence learning is of particular importance because considerable effort is devoted to (re)acquiring lost motor skills. Previous studies suggest that implicit motor sequence learning is preserved in stroke patients but were restricted to the spatial dimension, although the timing of single action components is as important as their spatial order. As the left parietal cortex is known to play a critical role in implicit timing and spatiotemporal integration, in this study we applied an adapted version of the SRT task designed to assess both spatial (different stimulus locations) and temporal (different response-stimulus intervals) aspects of motor learning to 24 right-handed patients with a single left-hemisphere (LH) stroke and 24 age-matched healthy controls. Implicit retrieval of sequence knowledge was tested both at Day 1 and after 24 hr (Day 2). Additionally, voxel-based lesion symptom mapping was used to investigate the neurobiological substrates of the behavioral effects. Although LH stroke patients showed a combined spatiotemporal learning effect that was comparable to that observed in controls, LH stroke patients did not show learning effects for the learning probes in which only one type of sequence information was maintained whereas the other one was randomized. Particularly on Day 2, patients showed significantly smaller learning scores for these two learning probes than controls. Voxel-based lesion symptom mapping analyses revealed for all learning probes that diminished learning scores on Day 2 were associated with lesions of the striatum. This might be attributed to its role in motor chunking and offline consolidation as group differences occurred on Day 2 only. The current results suggest that LH stroke patients rely on multimodal information (here: temporal and spatial information) when retrieving motor sequence knowledge and are very sensitive to any disruption of the learnt sequence information as they seem to build very rigid chunks preventing them from forming independent spatial and temporal sequence representations.
在中风后的康复过程中，运动序列学习尤为重要，因为人们需要付出大量努力来（重新）获得失去的运动技能。先前的研究表明，中风患者保留了内隐运动序列学习能力，但仅限于空间维度，尽管单个动作成分的时间安排与其空间顺序同样重要。由于已知左顶叶皮层在隐式时间安排和时空整合中起关键作用，在本研究中，我们对24名右利手、左侧半球（LH）单发性中风患者和24名年龄匹配的健康对照者应用了一种经过改编的序列反应时任务（SRT任务），旨在评估运动学习的空间（不同刺激位置）和时间（不同反应-刺激间隔）方面。在第1天和24小时后（第2天）都对内隐序列知识的提取进行了测试。此外，基于体素的损伤症状映射被用于研究行为效应的神经生物学基础。尽管LH中风患者表现出与对照组相当的时空联合学习效应，但对于仅保留一种序列信息而另一种信息随机化的学习探针，LH中风患者并未表现出学习效应。特别是在第2天，患者在这两种学习探针上的学习得分明显低于对照组。基于体素的损伤症状映射分析显示，对于所有学习探针，第2天学习得分的降低与纹状体损伤有关。这可能归因于纹状体在运动组块和离线巩固中的作用，因为组间差异仅在第2天出现。目前的结果表明，LH中风患者在提取运动序列知识时依赖多模态信息（此处为时间和空间信息），并且对所学序列信息的任何干扰都非常敏感，因为他们似乎构建了非常僵化的组块，从而阻止他们形成独立的空间和时间序列表征。
