Neuronal representation of visual salience in macaque posterior parietal cortex

我们发现，只有当目标由特定的刺激维度定义并且具有特定的刺激特征，例如形状单点，条形刺激时，后顶叶皮层（PPC）中的一个神经元子集才能将目标与其他刺激区分开来（条件依赖的目标选择），而另一个子集这样做，而不管刺激特征和目标定义的维度（条件无关的目标选择）。因此，在确定目标位置的神经表征中存在着大量的变化。这些明显不同类型的目标识别过程的共存表明，PPC可能位于从非空间的过渡到基于空间的目标选择发生的水平。

We found that a subset of neurons in the posterior parietal cortex (PPC) significantly discriminated the target from other stimuli only when the target was defined by a particular stimulus dimension and had specific stimulus features, such as a shape-singleton, bar stimulus (condition-dependent target selection), whereas another subset did so irrespective of the stimulus features and the target-defining dimension (condition-independent target selection). There was thus a great deal of variety in the neural representations specifying the locus of the target. The coexistence of these distinctly different types of target-discrimination processes suggests that the PPC may be situated at the level where the transition from nonspatial- to spatial-based target selection takes place.