Multiple hypothalamic cell populations encoding distinct visual information
Multiple hypothalamic cell populations encoding distinct visual information
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DOI：
10.1113/jphysiol.2010.199877
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发表时间：
2011-03-01
影响因子：
5.5
通讯作者：
Lucas, Robert J.
中科院分区：
文献类型：
--
作者：
Brown, Timothy M.;Wynne, Jonathan;Lucas, Robert J.
视网膜投射到视交叉上核（SCN）和各种其他下丘脑区域中的大脑“时钟”，允许光调节生理和行为的许多方面。这些下丘脑区域中光诱发反应的确切性质以及它们依赖于各种视网膜感光细胞的程度还不完全清楚。小鼠下丘脑的多电极记录揭示了四类视觉反应神经元，其活性通过照明（对比度）和/或根据稳态光水平（辐照度）的变化而改变。这些细胞出现在不同的位置，并且在其日常电活动中有所不同。一类的性质表明与调节SCN时钟直接相关，而其他类似乎适合于提供更直接的生理和行为调制。总之，这些发现建立了一个框架，了解光如何调节这样一个多样化的身体systems.Environmental照明深刻影响哺乳动物的生理和行为，通过对主昼夜节律振荡器在视交叉上核（SCN）和其他下丘脑核团的行动。在下丘脑细胞网络中，形成光诱发和自发活动的日常模式的视网膜和中枢机制在很大程度上仍然不清楚。同样，这些细胞所传递的感觉信息的确切性质也没有得到解决。在这里，我们着手解决这些问题，通过多电极记录从红锥敲入小鼠（Opn 1 mwR）的下丘脑。有了这个强大的小鼠模型，任何反应的光感受起源都可以根据它们对短波长和长波长光的相对敏感性来容易地识别。我们的实验表明，许多下丘脑细胞的放电模式的光水平的变化和/或根据照明的稳态水平的影响。这些“对比度”和“辐照度”反应主要分别由视锥和黑视蛋白光感受器驱动，视杆细胞表现出更微妙的影响。个别下丘脑神经元差异采样从这些信息流，引起四种不同的反应类型。SCN本身最常见的反应表型是持续激活。具有这种行为的细胞以与其对昼夜光夹带的独特贡献一致的方式对所有三种感光器类别作出反应。这些“持续”的细胞在我们的样本中也是独特的，在预测的一天中表达了昼夜节律的放电模式，具有最高的活性。令人惊讶的是，我们还发现了少数SCN神经元缺乏黑视蛋白衍生的辐照信号，并且仅对光转换做出反应，这使得杆锥对比度信号可能被路由到SCN输出目标而不影响相邻的昼夜节律振荡器。最后，延伸到室周下丘脑和腹侧丘脑的一系列细胞仅根据黑视素的活性而被兴奋或抑制。这些细胞似乎传达了视觉信号的过滤版本，适合纯粹根据环境辐照度调节生理/行为。总之，这些发现揭示了下丘脑细胞群编码不同质量的视觉信息。
Non-technical summaryA retinal projection to a brain 'clock' in the suprachiasmatic nuclei (SCN) and various other hypothalamic regions allows light to regulate many aspects of physiology and behaviour. The exact nature of light-evoked responses in these hypothalamic regions and the degree to which they rely upon the various classes of retinal photoreceptor is incompletely understood. Multielectrode recordings in the mouse hypothalamus reveal four classes of visually responsive neuron whose activity is altered by changes in illumination (contrast) and/or according to steady-state light levels (irradiance). These cells appear in different locations and vary in their daily profile of electrical activity. The properties of one class suggest a direct association with regulating the SCN clock, while the others appear suited to provide more direct modulations in physiology and behaviour. Together, these findings establish a framework for understanding how light regulates such a diverse array of body systems.Environmental illumination profoundly influences mammalian physiology and behaviour through actions on a master circadian oscillator in the suprachiasmatic nuclei (SCN) and other hypothalamic nuclei. The retinal and central mechanisms that shape daily patterns of light-evoked and spontaneous activity in this network of hypothalamic cells are still largely unclear. Similarly, the exact nature of the sensory information conveyed by such cells is unresolved. Here we set out to address these issues, through multielectrode recordings from the hypothalamus of red cone knockin mice (Opn1mwR). With this powerful mouse model, the photoreceptive origins of any response can be readily identified on the basis of their relative sensitivity to short and long wavelength light. Our experiments revealed that the firing pattern of many hypothalamic cells was influenced by changes in light levels and/or according to the steady state level of illumination. These 'contrast' and 'irradiance' responses were driven primarily by cone and melanopsin photoreceptors respectively, with rods exhibiting a much more subtle influence. Individual hypothalamic neurons differentially sampled from these information streams, giving rise to four distinct response types. The most common response phenotype in the SCN itself was sustained activation. Cells with this behaviour responded to all three photoreceptor classes in a manner consistent with their distinct contributions to circadian photoentrainment. These 'sustained' cells were also unique in our sample in expressing circadian firing patterns with highest activity during the mid projected day. Surprisingly, we also found a minority of SCN neurons that lacked the melanopsin-derived irradiance signal and responded only to light transitions, allowing for the possibility that rod-cone contrast signals may be routed to SCN output targets without influencing neighbouring circadian oscillators. Finally, an array of cells extending throughout the periventricular hypothalamus and ventral thalamus were excited or inhibited solely according to the activity of melanopsin. These cells appeared to convey a filtered version of the visual signal, suitable for modulating physiology/behaviour purely according to environmental irradiance. In summary, these findings reveal unexpectedly widespread hypothalamic cell populations encoding distinct qualities of visual information.