Ilg Uwe J, Schumann Stefan
Cognitive Neurology, Hertie-Institute of Clinical Brain Research, University of Tübingen, Otfried-Müller Strasse 27, D 72076 Tübingen, Germany.
J Neurophysiol. 2007 Jan;97(1):761-71. doi: 10.1152/jn.00278.2006. Epub 2006 Oct 25.
The contributions of the middle superior temporal area (MST) in the posterior parietal cortex of rhesus monkeys to the generation of smooth-pursuit eye movements as well as the contributions to motion perception are well established. Here, we present the first experimental evidence that this area also contributes to the generation of goal-directed hand movements toward a moving target. This evidence is based on the outcome of intracortical microstimulation experiments and transient lesions by small injections of muscimol at identified sites within the lateral part of area MST (MST-l). When microstimulation was applied during the execution of smooth-pursuit eye movements, postsaccadic eye velocity in the direction of the preferred direction of the stimulated site increased significantly (in 93 of 136 sites tested). When microstimulation was applied during a hand movement trial, the hand movement was displaced significantly in the same direction (in 28 of 39 sites tested). When we lesioned area MST-l transiently by injections of muscimol, steady-state eye velocity was exclusively reduced for ipsiversive smooth-pursuit eye movements. In contrast, hand movements were displaced toward the contralateral side, irrespective of the direction of the moving target. Our results provide evidence that area MST-l is involved in the processing of moving targets and plays a role in the execution of smooth-pursuit eye movements as well as visually guided hand movements.
恒河猴后顶叶皮质中的颞上中区（MST）对平稳跟踪眼球运动的产生以及对运动感知的贡献已得到充分证实。在此，我们提供了首个实验证据，表明该区域也有助于朝着移动目标产生目标导向的手部运动。这一证据基于皮质内微刺激实验的结果以及通过在MST区域外侧部分（MST-l）的特定部位小剂量注射蝇蕈醇进行短暂损伤的实验结果。在平稳跟踪眼球运动执行过程中施加微刺激时，受刺激部位偏好方向上的扫视后眼球速度显著增加（在测试的136个部位中有93个）。在手部运动试验中施加微刺激时，手部运动在相同方向上显著偏移（在测试的39个部位中有28个）。当我们通过注射蝇蕈醇短暂损伤MST-l区域时，同侧平稳跟踪眼球运动的稳态眼球速度仅降低。相比之下，手部运动向对侧偏移，与移动目标的方向无关。我们的结果提供了证据，表明MST-l区域参与移动目标的处理，并在平稳跟踪眼球运动以及视觉引导的手部运动的执行中发挥作用。
