Zackowski K M, Thach W T, Bastian A J
Kennedy Krieger Institute, Johns Hopkins University, 707 N Broadway, Baltimore, MD 21205, USA.
Exp Brain Res. 2002 Oct;146(4):511-22. doi: 10.1007/s00221-002-1191-9. Epub 2002 Aug 28.
We examined how cerebellar deficits in isolated reaching or grasping movements contribute to abnormalities in a combined reach and grasp movement, and whether people with cerebellar damage show abnormalities in the spatiotemporal relationships of reach and grasp movements. We studied subjects with cerebellar damage and matched controls as they performed a combined reach and grasp, an isolated reach, and an isolated grasp. These movements were performed under slow-accurate and fast speed conditions. Subjects were also tested for their ability to correctly estimate the target size based on visual information. We measured the three-dimensional position of the index finger, thumb and wrist joint during all tasks. Results showed that cerebellar subjects overestimated the target size to a greater extent than did controls. During movement testing, cerebellar subjects were impaired on isolated reach and isolated grasp. However, they did not worsen parameters of reach or grasp movements during the combined reach and grasp. Instead there were distinct deficits in the coupling of the reach and grasp movement. Compared with controls, cerebellar subjects showed abnormalities in the sequence of the reach and grasp movement and highly variable timing of peak grip aperture. In the slow-accurate condition, cerebellar subjects decomposed the reach and grasp movement into separate reach then grasp components, and produced multiple peaks in grip aperture. In the fast condition, cerebellar subjects did not decompose, produced a single peak grip aperture, and dropped the target more often. These results indicate that cerebellar damage can cause a specific breakdown in the coupling of reach and grasp movements. The cerebellum may be involved in combining reach and grasp movements into a single motor program.
我们研究了孤立的伸手或抓握动作中的小脑缺陷如何导致伸手和抓握联合动作出现异常，以及小脑损伤患者在伸手和抓握动作的时空关系上是否表现出异常。我们研究了小脑损伤患者以及与之匹配的对照组，观察他们进行伸手和抓握联合动作、孤立的伸手动作以及孤立的抓握动作时的情况。这些动作在慢速精确和快速条件下进行。还测试了受试者根据视觉信息正确估计目标大小的能力。在所有任务中，我们测量了食指、拇指和腕关节的三维位置。结果显示，小脑损伤患者比对照组更严重地高估目标大小。在动作测试中，小脑损伤患者在孤立的伸手动作和孤立的抓握动作上存在障碍。然而，在伸手和抓握联合动作期间，他们伸手或抓握动作的参数并未恶化。相反，伸手和抓握动作的耦合存在明显缺陷。与对照组相比，小脑损伤患者在伸手和抓握动作的顺序以及抓握孔径峰值的时间上表现出异常。在慢速精确条件下，小脑损伤患者将伸手和抓握动作分解为单独的先伸手后抓握的部分，并在抓握孔径上产生多个峰值。在快速条件下，小脑损伤患者没有进行分解，产生单个抓握孔径峰值，并且更频繁地掉落目标。这些结果表明，小脑损伤可导致伸手和抓握动作耦合的特定破坏。小脑可能参与将伸手和抓握动作整合为一个单一的运动程序。
