Heiser Laura M, Colby Carol L
Department of Neuroscience and Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
J Neurophysiol. 2006 May;95(5):2751-67. doi: 10.1152/jn.00054.2005. Epub 2005 Nov 16.
We explore the world around us by making rapid eye movements to objects of interest. Remarkably, these eye movements go unnoticed, and we perceive the world as stable. Spatial updating is one of the neural mechanisms that contributes to this perception of spatial constancy. Previous studies in macaque lateral intraparietal cortex (area LIP) have shown that individual neurons update, or "remap," the locations of salient visual stimuli at the time of an eye movement. The existence of remapping implies that neurons have access to visual information from regions far beyond the classically defined receptive field. We hypothesized that neurons have access to information located anywhere in the visual field. We tested this by recording the activity of LIP neurons while systematically varying the direction in which a stimulus location must be updated. Our primary finding is that individual neurons remap stimulus traces in multiple directions, indicating that LIP neurons have access to information throughout the visual field. At the population level, stimulus traces are updated in conjunction with all saccade directions, even when we consider direction as a function of receptive field location. These results show that spatial updating in LIP is effectively independent of saccade direction. Our findings support the hypothesis that the activity of LIP neurons contributes to the maintenance of spatial constancy throughout the visual field.
我们通过快速眼动看向感兴趣的物体来探索周围的世界。值得注意的是,这些眼动并未被察觉,我们将世界感知为稳定的。空间更新是有助于这种空间恒常性感知的神经机制之一。先前对猕猴顶叶内侧面皮质(LIP区)的研究表明,单个神经元在眼动时会更新或“重映射”显著视觉刺激的位置。重映射的存在意味着神经元能够获取来自远超出经典定义感受野区域的视觉信息。我们假设神经元能够获取视野中任何位置的信息。我们通过在系统改变刺激位置必须更新的方向时记录LIP神经元的活动来对此进行测试。我们的主要发现是单个神经元会在多个方向上重映射刺激痕迹,这表明LIP神经元能够获取整个视野的信息。在群体水平上,即使我们将方向视为感受野位置的函数,刺激痕迹也会随着所有扫视方向一起更新。这些结果表明LIP区的空间更新实际上与扫视方向无关。我们的发现支持了这样的假设,即LIP神经元的活动有助于在整个视野中维持空间恒常性。