RECEPTIVE-FIELDS AND FUNCTIONAL ARCHITECTURE OF MACAQUE V2
RECEPTIVE-FIELDS AND FUNCTIONAL ARCHITECTURE OF MACAQUE V2
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DOI：
10.1152/jn.1994.71.6.2517
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发表时间：
1994-06-01
影响因子：
2.5
通讯作者：
MOVSHON, JA
中科院分区：
文献类型：
--
作者：
LEVITT, JB;KIPER, DC;MOVSHON, JA
1.猕猴大脑皮质的视区V2是纹外视区中最大的，但令人惊讶的是，对其神经元特性知之甚少。我们对V2感受野的特性进行了定量的分析。选择我们的一组测量是为了区分反映小细胞(P)或大细胞(M)输入的神经元反应，并允许与其他视觉区域的类似测量进行比较；我们进一步描述了这些特性与V2.2的层流和细胞色素氧化酶(CO)结构的关系。我们记录了麻醉、瘫痪猕猴所有椎板中央5度和V2的CO区的单个单位的活动。我们研究了几何目标和漂移的正弦光栅对不同方向、空间频率、漂移率、对比度和颜色的响应。V2神经元的方位选择性和时空调谐与V1神经元无明显差异。就像在V1中一样，V2中的空间和时间调节似乎是可分离的，我们发现了与V1中发现的类似的简单细胞群体(更常见于中央3度)。平均而言，V2神经元的对比敏感度高于V1神经元，这可能反映了V2‘S较大感受野的输入的总和。许多V2神经元表现出一定程度的染色对抗性，对等亮度的颜色变化做出反应，但这些神经元与V1神经元的不同之处在于它们对锥体信号求和的线性。与其他人一致，我们发现对颜色、大小和运动具有选择性反应的神经元似乎确实聚集在不同的CO隔室。然而，这种性质不同的反应选择性的分离并不是绝对的，反应性质似乎也取决于每个隔室内的层流位置。正如其他人也注意到的那样，我们发现猕猴(与松鼠猴子不同)的CO条纹宽度并不总是不同。当CO的染色模式不明确时，我们依靠定性不同的细胞类型的分离，在某些情况下还依赖Cat-301染色模式来区分CO条纹。虽然在所有CO隔室和纹层中都发现了空气细胞类型，但无定向细胞在细条的第2-4层中更突出，方向选择性细胞在粗条的3B/4层中更突出，颜色选择细胞在细条和淡条纹的上层中，末端终止细胞主要在细条中的第4层之外。不同CO隔室中的细胞在空间、时间和对比度敏感性或取向选择性方面差异不大，尽管细条纹细胞更常见地没有定向，空间分辨率和对比度敏感性略低于粗条纹和淡条纹细胞。因此，虽然我们的结果与V2的功能分离大致一致，但它们也表明V2的生理组织比以前所认识的更均匀，与V2中P和M信号的持续分离不一致。
1. Visual area V2 of macaque monkey cerebral cortex is the largest of the extrastriate visual areas, yet surprisingly little is known of its neuronal properties. We have made a quantitative analysis of V2 receptive field properties. Our set of measurements was chosen to distinguish neuronal responses reflecting parvocellular (P) or magnocellular (M) inputs and to permit comparison with similar measurements made in other visual areas; we further describe the relationship of those properties to the laminar and cytochrome oxidase (CO) architecture of V2.2. We recorded the activity of single units representing the central 5 degrees in all laminae and CO divisions of V2 in anesthetized, paralyzed macaque monkeys. We studied responses to geometric targets and to drifting sinusoidal gratings that varied in orientation, spatial frequency, drift rate, contrast, and color.3. The orientation selectivity and spatial and temporal tuning of V2 neurons differed little from those in V1. As in V1, spatial and temporal tuning in V2 appeared separable, and we identified a population of simple cells (more common within the central 3 degrees) similar to those found in V1. Contrast sensitivity of V2 neurons was greater on average than in V1, perhaps reflecting the summation of inputs in V2's larger receptive fields. Many V2 neurons exhibited some degree of chromatic opponency, responding to isoluminant color variations, but these neurons differed from V1 in the linearity with which they summate cone signals.4. In agreement with others, we found that neurons with selective responses to color, size, and motion did seem to cluster in different CO compartments. However, this segregation of qualitatively different response selectivities was not absolute, and response properties also seemed to depend on laminar position within each compartment. As others also have noted, we found that CO stripe widths in the macaque(unlike in the squirrel monkey) did not consistently appear different. We relied on the segregation of qualitatively distinct cell types, and in some cases the pattern of Cat-301 staining as well, to distinguish CO stripes when the staining pattern of CO alone was ambiguous. Although air cell types were found in all CO compartments and laminae, unoriented cells were more prominent in layers 2-4 of ''thin'' stripes, direction-selective cells in layers 3B/4 of ''thick'' stripes, color-selective cells in the upper layers of thin and pale stripes, and end-stopped cells mainly outside of layer 4 in thin stripes.5. Cells in the different CO compartments differed little in their spatial, temporal, and contrast sensitivity or in their orientation selectivity, although thin-stripe cells more commonly were unoriented and had somewhat lower spatial resolution and contrast sensitivity than did cells in thick and pale stripes. Thus whereas our results are broadly consistent with functional segregation across V2, they also suggest that the physiological organization of V2 is substantially more homogeneous than has been previously appreciated and are inconsistent with continued segregation of P and M signals in V2.