Eskandar E N, Assad J A
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Nat Neurosci. 1999 Jan;2(1):88-93. doi: 10.1038/4594.
The role of the posterior parietal cortex (PPC) in the visual guidance of movements was studied in monkeys trained to use a joystick to guide a spot to a target. Visual and motor influences were dissociated by transiently occluding the spot and by varying the relationship between the direction of joystick and spot movements. We found a strong segregation of function in PPC during visual guidance. Neurons in area MST were selectively modulated by the direction of visible moving stimuli, whereas neurons in area MIP were selectively modulated by the direction of hand movement. In contrast, the selectivity of cells in the lateral intraparietal area (LIP) did not directly depend on either visual input or motor output, but rather seemed to encode a predictive representation of stimulus movement. These predictive signals may be an important link in visuomotor transformations.
在训练猴子使用操纵杆将一个光点引导至目标的实验中，研究了后顶叶皮质（PPC）在运动视觉引导中的作用。通过短暂遮挡光点以及改变操纵杆方向与光点运动之间的关系，分离了视觉和运动影响。我们发现在视觉引导过程中，PPC存在强烈的功能分离。MST区域的神经元受可见运动刺激方向的选择性调制，而MIP区域的神经元受手部运动方向的选择性调制。相比之下，顶内沟外侧区域（LIP）细胞的选择性并不直接依赖于视觉输入或运动输出，而是似乎编码了刺激运动的预测表征。这些预测信号可能是视觉运动转换中的一个重要环节。
