Rosa M G, Sousa A P, Gattass R
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil.
J Comp Neurol. 1988 Sep 15;275(3):326-45. doi: 10.1002/cne.902750303.
The representation of the visual field in the second visual area (V2) was reconstructed from multiunit visual responses and anatomical tracers. Receptive field plotting was performed during multiple recording sessions in seven Cebus apella monkeys under N2O/O2 and immobilized with pancuronium bromide. V2 forms a continuous belt of variable width around striate cortex (V1) except at the most anterior portion of the calcarine sulcus. In each hemisphere V2 contains a visuotopic representation of the contralateral visual hemifield. The representation of the vertical meridian is adjacent to that of V1 and forms the posterior border of V2. The representation of the fovea of V2 is adjacent to that of V1. The representation of the horizontal meridian (HM) is continuous with that of V1; then it splits to form the anterior border of V2, both dorsally and ventrally. The lower quadrant of the visual field is represented dorsally and the upper quadrant ventrally. The visual topography of V2 is coarser than that of V1. In V2, receptive fields corresponding to recording sites separated by a cortical distance of up to 4 mm may represent the same portion of the visual field. In three additional animals, combined injections of fluorescent tracers along the HM representation in V1 yielded two projection sites at the anterior border of V2. The split of the HM representation is estimated to occur at an eccentricity below 1 degree. Quantitative analysis showed that in V2 the representation of the central visual field is magnified relative to that of the periphery. The cortical magnification factor is greater along the isopolar dimension than along the isoeccentric one. Receptive field size in V2 increases with increasing eccentricity. In sections stained for myelin by the Heidenhein-Wöelcke method V2 can be distinguished from the surrounding cortex for most of its extent.
通过多单位视觉反应和解剖示踪剂重建了第二视觉区（V2）的视野表征。在七只僧帽猴处于N2O/O2麻醉状态并用泮库溴铵固定的情况下，在多次记录过程中进行了感受野绘图。V2在纹状皮质（V1）周围形成一条宽度可变的连续带，但在距状沟最前端部分除外。在每个半球中，V2包含对侧视觉半视野的视拓扑表征。垂直子午线的表征与V1相邻，并构成V2的后边界。V2中央凹的表征与V1相邻。水平子午线（HM）的表征与V1连续；然后它分开形成V2的前边界，在背侧和腹侧均如此。视野的下象限在背侧表征，上象限在腹侧表征。V2的视觉拓扑比V1的更粗糙。在V2中，对应于皮质距离相隔达4毫米的记录位点的感受野可能代表视野的同一部分。在另外三只动物中，沿着V1中HM表征联合注射荧光示踪剂，在V2的前边界产生了两个投射位点。HM表征的分开估计发生在偏心率低于1度处。定量分析表明，在V2中，中央视野的表征相对于周边视野被放大。皮质放大因子在等极维度上比在等偏心率维度上更大。V2中的感受野大小随着偏心率增加而增大。在用海登海因 - 韦尔克方法进行髓鞘染色的切片中，V2在其大部分范围内可与周围皮质区分开来。
