Snyder L H, Batista A P, Andersen R A
Division of Biology, California Institute of Technology, Pasadena 91125, USA.
Nature. 1997 Mar 13;386(6621):167-70. doi: 10.1038/386167a0.
To look at or reach for what we see, spatial information from the visual system must be transformed into a motor plan. The posterior parietal cortex (PPC) is well placed to perform this function, because it lies between visual areas, which encode spatial information, and motor cortical areas. The PPC contains several subdivisions, which are generally conceived as high-order sensory areas. Neurons in area 7a and the lateral intraparietal area fire before and during visually guided saccades. Other neurons in areas 7a and 5 are active before and during visually guided arm movements. These areas are also active during memory tasks in which the animal remembers the location of a target for hundreds of milliseconds before making an eye or arm movement. Such activity could reflect either visual attention or the intention to make movements. This question is difficult to resolve, because even if the animal maintains fixation while directing attention to a peripheral location, the observed neuronal activity could reflect movements that are planned but not executed. To address this, we recorded from the PPC while monkeys planned either reaches or saccades to a single remembered location. We now report that, for most neurons, activity before the movement depended on the type of movement being planned. We conclude that PPC contains signals related to what the animal intends to do.
为了看向或伸手去拿我们所看到的东西，视觉系统的空间信息必须被转化为一个运动计划。顶叶后皮质（PPC）具备执行这一功能的良好条件，因为它位于编码空间信息的视觉区域和运动皮质区域之间。PPC包含几个亚区，通常被认为是高阶感觉区域。7a区和顶内侧面区域的神经元在视觉引导的扫视之前及过程中会放电。7a区和5区的其他神经元在视觉引导的手臂运动之前及过程中会活跃。在记忆任务中，当动物在进行眼动或手臂运动前数百毫秒记住目标位置时，这些区域也会活跃。这种活动可能反映视觉注意力或运动意图。这个问题很难解决，因为即使动物在将注意力指向周边位置时保持注视，观察到的神经元活动也可能反映计划但未执行的运动。为了解决这个问题，我们在猴子计划伸手或扫视到单个记忆位置时记录PPC的活动。我们现在报告，对于大多数神经元，运动前的活动取决于所计划的运动类型。我们得出结论，PPC包含与动物意图做什么相关的信号。
