Visual response properties of neurons in the LGN of normally reared and visually deprived macaque monkeys
Visual response properties of neurons in the LGN of normally reared and visually deprived macaque monkeys
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DOI：
10.1152/jn.2001.85.5.2111
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发表时间：
2001-05-01
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;Schumer, RA;Movshon, JA
现在，人们很清楚地认识到，猴子和猫一样，存在着平行的视网膜-视网膜-皮层通路，而猫是最早且最彻底地记录了平行视觉通路的物种。目前尚不清楚的是，究竟有多少不同的通路通过猕猴外侧膝部核（LGN）的小细胞和大细胞分裂，这些通路与猫的X、Y和W通路有什么关系（同源或非同源），以及这些通路是否受到视觉剥夺的影响。为了解决这些分类和跨物种比较的问题，我们使用消色差刺激对9只猕猴的LGN小细胞和大细胞层的感受野特性进行了广泛的定量测量：4只正常饲养的猕猴和5只在出生时被眼睑缝合剥夺了单眼视力的猕猴。与之前的研究一致，我们发现大细胞神经元与细小细胞神经元的不同之处在于，它们对视交叉刺激的反应潜伏期更短，对亮度对比的敏感度更高，时间分辨率也更好。大细胞层的另一个特点是包含神经元，这些神经元在其感受野上非线性地累积亮度（Y细胞），其时间反应阶段随着刺激对比度的增加而减少（表明对比度增益控制机制）。在大多数空间参数的基础上，我们几乎没有发现马诺神经元和细小细胞神经元之间存在重大差异的证据，除了在任何偏心率下，感受野中心最小的神经元往往是细小细胞。所有参数在小细胞和大细胞群体中呈单模态连续分布，在每个分裂中没有亚群体的迹象。单眼剥夺导致明显的解剖效应：与未剥夺眼层相比，剥夺眼层的细胞苍白和萎缩，剥夺眼层的Cat-301免疫反应性基本均匀消失。然而，剥夺对LGN神经元的反应特性只有轻微的影响。被剥夺视力的眼睛驱动的马诺细胞和旁细胞层的神经元的非线性指数较低（即，通过它们的接受野的信号更线性地求和），并且反应程度较低。在被剥夺眼驱动的大细胞层中，神经元对视交叉刺激的反应潜伏期比未被剥夺眼驱动的神经元反应潜伏期略短，接受野包围略强。没有其他的反应参数受到剥夺的影响，也没有证据表明像猫那样失去了特定的细胞类别。
It is now well appreciated that parallel retino-geniculo-cortical pathways exist in the monkey as in the cat, the species in which parallel visual pathways were first and most thoroughly documented. What remains unclear is precisely how many separate pathways pass through the parvo- and magnocellular divisions of the macaque lateral geniculate nucleus (LGN), what relationships-homologous or otherwise-these pathways have to the cat's X, Y, and W pathways, and whether these are affected by visual deprivation. To address these issues of classification and trans-species comparison, we used achromatic stimuli to obtain an extensive set of quantitative measurements of receptive field properties in the parvo- and magnocellular laminae of the LGN of nine macaque monkeys: four normally reared and five monocularly deprived of vision by lid suture near the time of birth. In agreement with previous studies, we find that on average magnocellular neurons differ from parvocellular neurons by having shorter response latencies to optic chiasm stimulation, greater sensitivity to luminance contrast, and better temporal resolution. Magnocellular laminae are also distinguished by containing neurons that summate luminance over their receptive fields nonlinearly (Y cells) and whose temporal response phases decrease with increasing stimulus contrast (indicative of a contrast gain control mechanism). We found little evidence for major differences between magno- and parvocellular neurons on the basis of most spatial parameters except that at any eccentricity, the neurons with the smallest receptive field centers tended to be parvocellular. All parameters were distributed unimodally and continuously through the parvo- and magnocellular populations, giving no indications of subpopulations within each division. Monocular deprivation led to clear anatomical effects: cells in deprived-eye laminae were pale and shrunken compared with those in nondeprived eye laminae, and Cat-301 immunoreactivity in deprived laminae was essentially uniformly abolished. However, deprivation had only subtle effects on the response properties of LGN neurons. Neurons driven by the deprived eye in both magno- and parvocellular laminae had lower nonlinearity indices (i.e., summed signals across their receptive fields more linearly) and were somewhat less responsive. In magnocellular laminae driven by the deprived eye, neuronal response latencies to stimulation of the optic chiasm were slightly shorter than those in the nondeprived laminae, and receptive field surrounds were a bit stronger. No other response parameters were affected by deprivation, and there was no evidence for loss of a specific cell class as in the cat.