Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, 39216, USA.
Department of Ophthalmology, University of Mississippi Medical Center, Jackson, MS, 39216, USA.
Brain Struct Funct. 2018 Jan;223(1):371-390. doi: 10.1007/s00429-017-1503-2. Epub 2017 Aug 29.
The zona incerta contains GABAergic neurons that project to the superior colliculus in the cat and rat, suggesting that it plays a role in gaze changes. However, whether this incertal connection represents a general mammalian pattern remains to be determined. We used neuronal tracers to examine the zona incerta connections with the midbrain tectum in the gray squirrel and macaque monkey. Collicular injections in both species revealed that most incertotectal neurons lay in the ventral layer, but anterogradely labeled tectoincertal terminals were found in both the dorsal and ventral layers. In the monkey, injections of the pretectum also produced retrograde labeling, but mainly in the dorsal layer. The dendritic fields of incertotectal and incertopretectal cells were generally contained within the layer inhabited by their somata. The macaque, but not the squirrel, zona incerta extended dorsolaterally, within the external medullary lamina. Zona incerta injections produced retrogradely labeled neurons in the superior colliculus of both species. In the squirrel, most cells inhabited the lower sublamina of the intermediate gray layer, but in the monkey, they were scattered throughout the deeper layers. Labeled cells were present among the pretectal nuclei in both species. Labeled terminals were concentrated in the lower sublamina of the intermediate gray layer of both species, but were dispersed among the pretectal nuclei. In summary, an incertal projection that is concentrated on the collicular motor output layers and that originates in the ventral layer of the ipsilateral zona incerta is a common mammalian feature, suggesting an important role in collicular function.
脑脚间核含有 GABA 能神经元，这些神经元投射到猫和大鼠的上丘，表明它在眼球运动变化中发挥作用。然而，这种脚间核的连接是否代表了一种普遍的哺乳动物模式还有待确定。我们使用神经元示踪剂研究了灰松鼠和猕猴中脑脚间核与中脑顶盖的连接。在这两种物种中，丘系内注射显示大多数脚间核投射神经元位于腹侧层，但顺行标记的顶盖脚间核末端位于背侧和腹侧层。在猴子中，前脑桥的注射也产生逆行标记，但主要在背侧层。脚间核投射和脚间顶盖细胞的树突野通常包含在其胞体所在的层内。猴的脚间核向背外侧延伸，位于外髓质层内，但松鼠没有。脚间核注射在两种物种的上丘中都产生了逆行标记神经元。在松鼠中，大多数细胞位于中间灰色层的较低亚层，但在猴子中，它们分散在更深的层中。在两种物种中，标记细胞存在于顶盖核之间。标记的末端集中在两种物种中间灰色层的较低亚层，但在顶盖核之间分散。总之，一种集中在上丘运动输出层的脚间核投射，起源于同侧脚间核的腹侧层，是哺乳动物的共同特征，表明它在丘系功能中起着重要作用。
