Jones H E, Sillito A M
Department of Visual Science, Institute of Ophthalmology, London, UK.
Eur J Neurosci. 1994 Jul 1;6(7):1199-204. doi: 10.1111/j.1460-9568.1994.tb00618.x.
Perigeniculate cells receive visual input from the dorsal lateral geniculate nucleus (dLGN) and from the visual cortex. In contrast to the extensive literature documenting dLGN and cortical cell responses, comparatively little quantitative data exists for perigeniculate nucleus cells, and very little is known about the role of the corticofugal input to the perigeniculate nucleus. We have previously shown that dLGN relay cells have sharply length-tuned receptive fields and that a significant component of this is dependent on the corticofugal system. In this report, we have explored the length-response properties of perigeniculate nucleus cells in the presence and absence of corticofugal feedback. The response profiles of most perigeniculate nucleus cells contrasted markedly with the sharply length-tuned fields of dLGN cells, but exhibited a notable resemblance to those exhibited by VI cells with short summation lengths, which have recently been shown to constitute a considerable proportion of the layer VI cell population. This might suggest that the responses of perigeniculate nucleus cells to long bars derive from their cortical input. However, our data failed to reveal a discernible change in their profiles after removal of the corticofugal drive. This surprising observation implies that their length-tuning profiles follow from subcortical circuitry. The ways in which this might occur are discussed.
膝周细胞接收来自背外侧膝状核（dLGN）和视觉皮层的视觉输入。与大量记录dLGN和皮层细胞反应的文献相比，关于膝周核细胞的定量数据相对较少，而且对于皮质离心输入到膝周核的作用了解甚少。我们之前已经表明，dLGN中继细胞具有尖锐的长度调谐感受野，并且其中一个重要组成部分依赖于皮质离心系统。在本报告中，我们探讨了在有和没有皮质离心反馈的情况下膝周核细胞的长度反应特性。大多数膝周核细胞的反应轮廓与dLGN细胞尖锐的长度调谐场明显不同，但与具有短总和长度的VI细胞所表现出的轮廓有显著相似之处，最近已表明这些细胞在VI层细胞群体中占相当大的比例。这可能表明膝周核细胞对长条的反应源自其皮质输入。然而，我们的数据未能揭示在去除皮质离心驱动后它们的轮廓有明显变化。这一惊人的观察结果意味着它们的长度调谐轮廓源自皮层下回路。本文讨论了这种情况可能发生的方式。
