Uhlrich D J, Cucchiaro J B, Sherman S M
Department of Neurobiology and Behavior, State University of New York, Stony Brook 11794.
J Neurosci. 1988 Dec;8(12):4565-75. doi: 10.1523/JNEUROSCI.08-12-04565.1988.
In mammals, the retinogeniculocortical pathway is the primary afferent route to visual cortex. The flow of information along this pathway can be modulated at the thalamic level (i.e., at the lateral geniculate nucleus) as a function of arousal, attention, and phenomena such as eye movements. Physiological studies indicate that an important source of this state-dependent influence on geniculate neuronal responsiveness is the parabrachial region of the brain stem. We used the anterograde tracer Phaseolus vulgaris leucoagglutinin to study the anatomical connections between the parabrachial region and the lateral geniculate nucleus. Labeled parabrachial axons are found throughout the thalamus, including all laminae of the lateral geniculate nucleus, the lateral posterior-pulvinar complex, the ventral lateral geniculate nucleus, the perigeniculate nucleus, and the reticular nucleus of the thalamus. Within these nuclei, the axons exhibit sporadically branched terminal arbors with boutons mostly en passant. Serial reconstructions indicate that individual parabrachial axons that innervate the lateral geniculate nucleus may terminate in other visual thalamic nuclei as well, but not in thalamic nuclei that subserve other modalities. Finally, the labeled parabrachial axons are morphologically heterogeneous; they differ in their innervation targets, terminal arbor shape, and the size spectrum of their boutons. These data suggest that this portion of the ascending parabrachial pathway, which may be functionally diverse, coordinates the responsiveness of the varied thalamic nuclei involved with vision.
在哺乳动物中，视网膜 - 丘脑 - 皮质通路是通向视觉皮质的主要传入路径。沿着这条通路的信息流可在丘脑水平（即外侧膝状体核）根据觉醒、注意力以及眼球运动等现象进行调节。生理学研究表明，脑干臂旁区域是这种对膝状体神经元反应性的状态依赖性影响的一个重要来源。我们使用顺行示踪剂菜豆白细胞凝集素研究臂旁区域与外侧膝状体核之间的解剖学联系。在整个丘脑都发现了标记的臂旁轴突，包括外侧膝状体核的所有层、外侧后 - 丘脑复合体、腹侧外侧膝状体核、膝状体周围核以及丘脑网状核。在这些核内，轴突呈现出偶尔分支的终末树突，其终扣大多为串珠状。连续重建表明，支配外侧膝状体核的单个臂旁轴突也可能终止于其他视觉丘脑核，但不会终止于服务于其他感觉模态的丘脑核。最后，标记的臂旁轴突在形态上是异质的；它们在支配目标、终末树突形状以及终扣的大小范围方面存在差异。这些数据表明，这条上行臂旁通路的这一部分可能在功能上具有多样性，它协调了参与视觉的各种丘脑核的反应性。
