Faculty of Biology and Biotechnology, Ruhr University Bochum, D-44780 Bochum, Germany.
J Neurophysiol. 2010 Jun;103(6):3153-66. doi: 10.1152/jn.00989.2009. Epub 2010 Mar 31.
When reaching for an object, primates usually look at their target before touching it with the hand. This gaze movement prior to the arm movement allows target fixation, which is usually prolonged until the target is reached. In this manner, a stable image of the object is provided on the fovea during the reach, which is crucial for guiding the final part of the hand trajectory by visual feedback. Here we investigated a neural substrate possibly responsible for this behavior. In particular we tested the influence of reaching movements on neurons recorded at the rostral pole of the superior colliculus (rSC), an area classically related to fixation. Most rSC neurons showed a significant increase in their activity during reaching. Moreover, this increase was particularly high when the reaching movements were preceded by corresponding saccades to the targets to be reached, probably revealing a stronger coupling of the oculo-manual neural system during such a natural task. However, none of the parameters tested--including movement kinematics and target location--was found to be closely related to the observed increase in neural activity. Thus the increase in activity during reaching was found to be rather nonspecific except for its dependence on whether the reach was produced in isolation or in combination with a gaze movement. These results identify the rSC as a neural substrate sufficient for gaze anchoring during natural reaching movements, placing its activity at the core of the neural system dedicated to eye-hand coordination.
当灵长类动物伸手去拿物体时，通常会在用手触摸物体之前先看一下目标。这种手臂运动之前的注视运动可以实现对目标的固定，通常会持续到目标被触及。通过这种方式，在伸手过程中，物体的稳定图像被提供在中央凹上，这对于通过视觉反馈引导手轨迹的最后部分至关重要。在这里，我们研究了一个可能负责这种行为的神经基质。特别是，我们测试了伸手运动对记录在高级视丘（rSC）前极的神经元的影响，rSC 是一个与固定有关的经典区域。大多数 rSC 神经元在伸手时表现出显著的活动增加。此外，当伸手运动之前伴随着对应于要触及的目标的扫视时，这种增加尤其高，可能揭示了在这种自然任务中眼球和手动神经系统的更强耦合。然而，在测试的所有参数中，包括运动运动学和目标位置，都没有发现与观察到的神经元活动增加密切相关。因此，在伸手过程中观察到的活动增加除了取决于伸手是单独进行还是与注视运动相结合之外，发现其具有相当的非特异性。这些结果表明 rSC 是一个用于在自然伸手运动中固定注视的神经基质，其活动处于专门用于眼手协调的神经网络的核心。
