Rosa M G, Schmid L M
Department of Physiology and Pharmacology, University of Queensland, Brisbane, Australia.
J Comp Neurol. 1995 Aug 21;359(2):272-99. doi: 10.1002/cne.903590207.
To define the number and limits of the visual areas in the primate extrastriate cortex, the visuotopy of the dorsal convexity and medial wall was studied by electrophysiological recordings in five marmosets anaesthetised with sufentanil and nitrous oxide and paralysed with pancuronium bromide. We identified five visuotopic representations in and around the densely myelinated zone between visual area 2 (V2) and the posterior parietal cortex. Most of the densely myelinated zone is formed by the homologue of the owl monkey's dorsomedial area (DM); thus, we also termed this area DM in the marmoset. Within DM, the lower quadrant representation is continuous, with central vision represented laterally, peripheral vision medially, the horizontal meridian caudally, and the vertical meridian rostrally. In contrast, the upper quadrant representation is split, with the central portion represented at the lateral edge of DM on the dorsal surface, and the periphery along the midline. Two other visual field representations, corresponding to the dorsointermediate area (DI) and to a new subdivision termed the dorsoanterior area (DA), are also densely myelinated but can be distinguished from DM based on the separation of the bands of Baillarger and visual topography. In addition, a homologue of the medial visual area (M) was identified. Our results reveal a highly complex visuotopy in primate cortex, with local discontinuities in representation and borders between areas that are often not coincident with either the horizontal or the vertical meridian. The topography of the dorsal extrastriate cortex in the marmoset strongly suggests that both visual area 3 (V3) and the parietooccipital area (PO) of other primates are portions of a single visuotopic representation, DM, and calls into question the existence of visual areas with partial or quadrantic representations of the visual field.
为了确定灵长类动物纹外皮层视觉区域的数量和界限，我们通过电生理记录研究了五只经舒芬太尼和一氧化二氮麻醉并用泮库溴铵麻痹的狨猴背凸和内侧壁的视拓扑结构。我们在视觉区域2（V2）和后顶叶皮层之间的密集髓鞘区及其周围确定了五种视拓扑表征。密集髓鞘区的大部分由夜猴背内侧区（DM）的同源物形成；因此，我们在狨猴中也将该区域称为DM。在DM内，下象限表征是连续的，中央视觉在外侧，周边视觉在内侧，水平子午线在尾侧，垂直子午线在嘴侧。相比之下，上象限表征是分开的，中央部分在背表面DM的外侧边缘，周边部分沿着中线。另外两种视野表征，对应于背中间区（DI）和一个新的细分区域背前区（DA），也有密集髓鞘，但可以根据拜洛嘉带的分离和视拓扑结构与DM区分开来。此外，还确定了内侧视觉区（M）的同源物。我们的结果揭示了灵长类动物皮层中高度复杂的视拓扑结构，表征存在局部不连续性，区域之间的边界通常与水平或垂直子午线不一致。狨猴背侧纹外皮层的拓扑结构强烈表明，其他灵长类动物的视觉区域3（V3）和顶枕区（PO）都是单一视拓扑表征DM的一部分，并对具有部分或象限视野表征的视觉区域的存在提出了质疑。
