Konen Christina S, Kastner Sabine
Department of Psychology, Center for the Study of Brain, Mind, and Behavior, and Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey 08540, USA.
J Neurosci. 2008 Aug 13;28(33):8361-75. doi: 10.1523/JNEUROSCI.1930-08.2008.
Recent imaging studies have shown that the human posterior parietal cortex (PPC) contains four topographically organized areas along the intraparietal sulcus (IPS1-IPS4). Using a memory-guided saccade paradigm, we confirmed the locations and retinotopic organization of IPS1-IPS4 and identified two additional areas, IPS5 and superior parietal lobule 1 (SPL1). IPS5 is located at the intersection of the intraparietal and postcentral sulcus; SPL1 branches off the IPS and extends into the superior parietal lobule. Both areas, as well as IPS1-IPS4, each contain a representation of the contralateral visual hemifield. We then probed core functions of the dorsal pathway in these areas, that is, the representation of eye movements and visual motion, to compare the functional characteristics of human PPC to physiologically and anatomically defined areas in monkey PPC. First, as in monkey PPC, a gradient representation of eye movements was found along the IPS with decreasing responses for saccades and increasing responses for smooth pursuit eye movements from posterior/medial to anterior/lateral. The greatest preference for saccades was found in SPL1 and for smooth pursuit in IPS5. Second, and again similar to monkey PPC, all topographically organized PPC areas responded to different types of motion including planar, circular, and radial optic flow, as assessed using adaptation paradigms. Areas in posterior IPS preferred radial optic flow over planar motion, whereas areas in anterior PPC did not show preference for a particular motion type. Together, our results indicate strikingly similar characteristics in the general functional organization of human and monkey PPC, but also reveal some notable differences.
最近的影像学研究表明，人类后顶叶皮层（PPC）沿顶内沟包含四个具有拓扑组织的区域（IPS1-IPS4）。使用记忆引导扫视范式，我们确认了IPS1-IPS4的位置和视网膜拓扑组织，并确定了另外两个区域，IPS5和顶上小叶1（SPL1）。IPS5位于顶内沟和中央后沟的交汇处；SPL1从IPS分支并延伸到顶上小叶。这两个区域以及IPS1-IPS4，每个区域都包含对侧视觉半视野的表征。然后，我们探究了这些区域中背侧通路的核心功能，即眼动和视觉运动的表征，以比较人类PPC与猴子PPC中生理和解剖学定义区域的功能特征。首先，与猴子PPC一样，沿着IPS发现了眼动的梯度表征，从后/内侧到前/外侧，扫视反应逐渐减少，平稳跟踪眼动反应逐渐增加。在SPL1中发现对扫视的偏好最大，在IPS5中对平稳跟踪的偏好最大。其次，同样与猴子PPC相似，所有具有拓扑组织的PPC区域对不同类型的运动都有反应，包括平面、圆形和径向光流，这是使用适应范式评估的。顶内沟后部的区域更喜欢径向光流而不是平面运动，而顶叶前部的区域对特定运动类型没有偏好。总之，我们的结果表明，人类和猴子PPC的一般功能组织具有惊人的相似特征，但也揭示了一些显著差异。
