Morin L P
Department of Psychiatry, Health Science Center, State University of New York at Stony Brook.
Brain Res Brain Res Rev. 1994 Jan;19(1):102-27. doi: 10.1016/0165-0173(94)90005-1.
The retina transduces photic stimuli and transmits that information centrally for further processing. This review emphasizes the fact that the nervous system components governing circadian rhythmicity constitute a specialized subdivision of the vertebrate visual system. The brain houses different targets for retinal efferents parcellated according circadian or non-circadian function. Although the suprachiasmatic nucleus (SCN), being the site of the master circadian clock, is necessary for the generation of circadian rhythmicity, precise phase regulation of any rhythm is subject to modulation by SCN-afferent processes. Photic information necessary for entrainment arrives at the SCN via the retinohypothalamic tract. The geniculohypothalamic tract, originating in the intergeniculate leaflet (IGL), provides a secondary route by which photic information can reach the SCN. It also projects extensively to the contralateral IGL and receives reciprocal input from the SCN region. An interaction between the circadian and non-circadian visual systems may exist through connections of the superior colliculus with ventrolateral geniculate leaflet (VLG) and IGL. The SCN, IGL, VLG and superior colliculus are all innervated by serotonin-containing fibers. The following observations are likely to have an impact beyond the rhythm field itself: certain transneuronal tracers label only the circadian visual system; c-fos protein synthesis is induced in the circadian, but not non-circadian, visual system by a phasically active stimulus; blockade of SCN action potentials is unable to alter circadian rhythmicity; transplantation of dispersed fetal SCN cells to arrhythmic adults restores circadian periodicity, but not phase response to light; and the IGL is actually a very extensive part of the lateral geniculate complex.
视网膜将光刺激转化为神经信号，并将这些信息传递到中枢进行进一步处理。本综述强调了这样一个事实，即控制昼夜节律的神经系统组成部分构成了脊椎动物视觉系统的一个特殊分支。大脑中存在着根据昼夜节律或非昼夜节律功能划分的视网膜传出神经的不同靶点。虽然作为主生物钟所在位置的视交叉上核（SCN）对于昼夜节律的产生是必需的，但任何节律的精确相位调节都受到SCN传入过程的调制。同步所需的光信息通过视网膜下丘脑束到达SCN。起源于外侧膝状体间叶（IGL）的膝状体下丘脑束提供了光信息到达SCN的第二条途径。它还广泛投射到对侧IGL，并接受来自SCN区域的相互输入。昼夜节律和非昼夜节律视觉系统之间可能通过上丘与腹外侧膝状体间叶（VLG）和IGL的连接而存在相互作用。SCN、IGL、VLG和上丘都接受含5-羟色胺纤维的支配。以下观察结果可能对节律领域本身之外产生影响：某些跨神经元示踪剂仅标记昼夜节律视觉系统；在昼夜节律视觉系统而非非昼夜节律视觉系统中，相位活跃刺激可诱导c-fos蛋白合成；阻断SCN动作电位无法改变昼夜节律；将分散的胎儿SCN细胞移植到无节律的成体中可恢复昼夜节律，但不能恢复对光的相位反应；并且IGL实际上是外侧膝状体复合体中非常广泛的一部分。
