Caruso Valeria C, Pages Daniel S, Sommer Marc A, Groh Jennifer M
Duke Institute for Brain Sciences, Duke University , Durham, North Carolina.
Center for Cognitive Neuroscience, Duke University , Durham, North Carolina.
J Neurophysiol. 2018 Apr 1;119(4):1411-1421. doi: 10.1152/jn.00584.2017. Epub 2017 Dec 20.
We accurately perceive the visual scene despite moving our eyes ~3 times per second, an ability that requires incorporation of eye position and retinal information. In this study, we assessed how this neural computation unfolds across three interconnected structures: frontal eye fields (FEF), intraparietal cortex (LIP/MIP), and the superior colliculus (SC). Single-unit activity was assessed in head-restrained monkeys performing visually guided saccades from different initial fixations. As previously shown, the receptive fields of most LIP/MIP neurons shifted to novel positions on the retina for each eye position, and these locations were not clearly related to each other in either eye- or head-centered coordinates (defined as hybrid coordinates). In contrast, the receptive fields of most SC neurons were stable in eye-centered coordinates. In FEF, visual signals were intermediate between those patterns: around 60% were eye-centered, whereas the remainder showed changes in receptive field location, boundaries, or responsiveness that rendered the response patterns hybrid or occasionally head-centered. These results suggest that FEF may act as a transitional step in an evolution of coordinates between LIP/MIP and SC. The persistence across cortical areas of mixed representations that do not provide unequivocal location labels in a consistent reference frame has implications for how these representations must be read out. NEW & NOTEWORTHY How we perceive the world as stable using mobile retinas is poorly understood. We compared the stability of visual receptive fields across different fixation positions in three visuomotor regions. Irregular changes in receptive field position were ubiquitous in intraparietal cortex, evident but less common in the frontal eye fields, and negligible in the superior colliculus (SC), where receptive fields shifted reliably across fixations. Only the SC provides a stable labeled-line code for stimuli across saccades.
尽管我们的眼睛每秒移动约3次，但我们仍能准确感知视觉场景，这种能力需要整合眼睛位置和视网膜信息。在本研究中，我们评估了这种神经计算是如何在三个相互连接的结构中展开的：额叶眼区（FEF）、顶内皮层（LIP/MIP）和上丘（SC）。在头部固定的猴子进行从不同初始注视点开始的视觉引导扫视时，对单神经元活动进行了评估。如先前所示，大多数LIP/MIP神经元的感受野会随着每个眼睛位置在视网膜上转移到新的位置，并且这些位置在以眼睛为中心或头部为中心的坐标（定义为混合坐标）中彼此之间没有明显的关联。相比之下，大多数SC神经元的感受野在以眼睛为中心的坐标中是稳定的。在FEF中，视觉信号介于这些模式之间：约60%是以眼睛为中心的，而其余的则显示出感受野位置、边界或反应性的变化，使得反应模式为混合或偶尔以头部为中心。这些结果表明，FEF可能在LIP/MIP和SC之间的坐标演化中起到过渡步骤的作用。在一个一致的参考框架中不能提供明确位置标签的混合表征在各个皮层区域的持续存在，对于这些表征必须如何读出具有重要意义。新发现与值得注意之处 我们如何利用移动的视网膜将世界感知为稳定的，这一点还知之甚少。我们比较了三个视觉运动区域中不同注视位置的视觉感受野的稳定性。感受野位置的不规则变化在顶内皮层中普遍存在，在额叶眼区明显但不太常见，在上丘（SC）中可忽略不计，在SC中感受野在扫视过程中可靠地移动。只有SC为扫视过程中的刺激提供稳定的标记线编码。
