Section Computational Sensomotorics, Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, and Centre for Integrative Neuroscience, University of Tübingen, Germany;
J Neurophysiol. 2013 Nov;110(10):2337-49. doi: 10.1152/jn.00062.2013. Epub 2013 Aug 21.
We examined the influence of focal cerebellar lesions on working memory (n-back task), gait, and the interaction between working memory and different gait tasks in a dual-task paradigm. The analysis included 17 young patients with chronic focal lesions after cerebellar tumor resection and 17 age-matched controls. Patients have shown mild to moderate ataxia. Lesion sites were examined on the basis of structural magnetic resonance imaging. N-back tasks were executed with different levels of difficulty (n = 1-4) during sitting (baseline), treadmill walking, and treadmill tandem walking (dual-task conditions). Patients exhibited decreased n-back performance particularly at difficult n-back levels and in dual-task conditions. Voxel-based lesion-symptom mapping revealed that decreased baseline n-back performance was associated with lesions of the posterolateral cerebellar hemisphere and the dentate nucleus. By contrast, decreased n-back performance in dual-task conditions was more associated with motor-related areas including dorsal portions of the dentate and the interposed nucleus, suggesting a prioritization of the motor task. During baseline walking, increased gait variability was associated with lesions in medial and intermediate regions, whereas for baseline tandem gait, lesions in the posterolateral hemispheres and the dentate nucleus became important. Posterolateral regions overlapped with regions related to baseline n-back performance. Consistently, we observed increased tandem gait variability with growing n-back difficulty in the dual-task condition. These findings suggest that dual-task effects in cerebellar patients are at least partially caused by a common involvement of posterolateral cerebellar regions in working memory and complex motor tasks.
我们研究了小脑局灶性病变对工作记忆（n-back 任务）、步态以及双任务范式下工作记忆与不同步态任务之间相互作用的影响。分析包括 17 例小脑肿瘤切除术后慢性局灶性病变的年轻患者和 17 例年龄匹配的对照组。患者表现为轻至中度共济失调。根据结构磁共振成像检查病变部位。在坐姿（基线）、跑步机行走和跑步机串联行走（双任务条件）下，执行不同难度水平（n=1-4）的 n-back 任务。患者在困难 n-back 水平和双任务条件下的 n-back 表现下降。基于体素的病变-症状映射显示，基线 n-back 表现下降与小脑后外侧叶和齿状核的病变有关。相比之下，双任务条件下 n-back 表现下降与包括齿状核和中间核背侧部分在内的运动相关区域更相关，表明运动任务的优先级。在基线行走期间，步态变异性增加与内侧和中间区域的病变有关，而在基线串联步态期间，后外侧半球和齿状核的病变变得重要。后外侧区域与与基线 n-back 表现相关的区域重叠。一致地，我们观察到在双任务条件下，随着 n-back 难度的增加，串联步态变异性增加。这些发现表明，小脑患者的双任务效应至少部分是由于后外侧小脑区域在工作记忆和复杂运动任务中共同参与引起的。
