Visual information is initially represented in retinotopic coordinates and later in craniotopic coordinates. Psychophysical evidence suggests that visual information is further represented in more general coordinates related to the external world; however, the neural basis of nonegocentric coordinates remains elusive. This study investigates the automatic transformation from egocentric to nonegocentric coordinates in the macaque precuneus (two males, one female), identified by a functional imaging study as a key area for nonegocentric representation. We found that 6.2% of neurons in the precuneus have receptive fields (RFs) anchored to the background rather than to the retina or the head, while 16% had traditional retinotopic RFs. Notably, these two types were not exclusive: many background-centric neurons initially encode a stimulus' position in retinotopic coordinates (up to ~90 ms from the stimulus onset) but later shift to background coordinates, peaking at ~150 ms. Regarding retinotopic information, the stimulus dominated the initial period, whereas the background dominated the later period. In the absence of a background, there is a dramatic surge in retinotopic information about the stimulus during the later phase, clearly delineating two distinct periods of retinotopic encoding: one focusing on the figure to be attended and another on the background. These findings suggest that the initial retinotopic information of the stimulus is combined with the background retinotopic information in a subsequent stage, yielding a more stable representation of the stimulus relative to the background through time-division multiplexing.

视觉信息最初以视网膜坐标表示，后来以颅位坐标表示。心理物理学证据表明，视觉信息进一步表示在与外部世界相关的更一般的坐标中;然而，非自我中心坐标的神经基础仍然难以捉摸。本研究调查了楔前叶 （两只雄性，一只雌性） 从自我中心到非自我中心坐标的自动转变，由功能成像研究确定为非自我中心表征的关键区域。我们发现楔前叶中 6.2% 的神经元具有锚定在背景而不是视网膜或头部的感受野 （RF），而 16% 具有传统的视网膜 RF。值得注意的是，这两种类型的神经元并不排斥：许多以背景为中心的神经元最初以视网膜坐标编码刺激的位置（从刺激开始后最多 ~90 毫秒），但后来转移到背景坐标， 峰值为 ~150 毫秒。关于视网膜信息，刺激在初始阶段占主导地位，而背景在后期占主导地位。在没有背景的情况下，在后期，有关刺激的视网膜信息急剧激增，清楚地描绘了视网膜编码的两个不同时期：一个专注于要关注的人物，另一个专注于背景。这些发现表明，刺激的初始视网膜信息与后续阶段的背景视网膜信息相结合，通过时分多路复用产生刺激相对于背景的更稳定表示。