Jeon C J, Mize R R
Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis 38163.
J Comp Neurol. 1993 Nov 1;337(1):127-50. doi: 10.1002/cne.903370109.
Fibers containing acetylcholine (ACh) form distinct patches in the dorsal intermediate gray layer (IGL) of the cat superior colliculus (SC). Although these patches are known to overlap several afferent projections to SC, it is not known whether they are associated with specific postsynaptic cell groups. We have examined the relationship of these ACh fiber patches to specific efferent cell groups by combining retrograde transport of horseradish peroxidase (HRP) with choline acetyltransferase (ChAT) immunocytochemistry. Successful HRP injections were made into the predorsal bundle (PB), the tecto-pontine-bulbar pathway (TPB) and the cuneiform region (CFR), the inferior olive (IO), the dorsolateral pontine gray nucleus (PGD), and the pedunculopontine tegmental nucleus (PPTN). The distribution of HRP-labeled neurons which project to these targets was mapped by a computer-based microscope plotter. Distinct clusters of HRP-labeled neurons in the IGL were seen after three injections into the mesencephalic reticular formation that involved the caudal TPB and cuneiform region (CFR), and after one injection into the medial accessory nucleus of IO. As many as seven clusters of labeled neurons were found in some sections through the caudal one-half of SC after the TPB/CFR injections. Each cluster consisted of 3-20 cells, all of which were small to medium in size. In sections also tested for ChAT, the cell clusters in the TPB/CFR cases were found to overlap precisely the ACh patches in the IGL. In addition, SC neurons projecting to the IO formed clusters above the ChAT patches and in the intermediate white layer (IWL) of SC. None of the other HRP injections produced any obvious cell clusters in the deep layers of SC. These results are the first to show that specific cell groups, distinguished by size and projection site, form clusters that match the patch-like innervation of cholinergic afferents to SC. This modular organization may correspond to saccade-related cells that have also been reported to be organized into clusters in the cat SC.
含有乙酰胆碱（ACh）的纤维在猫上丘（SC）的背侧中间灰质层（IGL）形成独特的斑块。尽管已知这些斑块与投射到上丘的几种传入投射重叠，但尚不清楚它们是否与特定的突触后细胞群相关。我们通过将辣根过氧化物酶（HRP）的逆行运输与胆碱乙酰转移酶（ChAT）免疫细胞化学相结合，研究了这些乙酰胆碱能纤维斑块与特定传出细胞群的关系。成功地将HRP注射到背侧前束（PB）、顶盖 - 脑桥 - 延髓通路（TPB）和楔形区（CFR）、下橄榄核（IO）、脑桥背外侧灰质核（PGD）和脚桥被盖核（PPTN）。通过基于计算机的显微镜绘图仪绘制投射到这些靶点的HRP标记神经元的分布图。在向涉及尾侧TPB和楔形区（CFR）的中脑网状结构进行三次注射后，以及向IO内侧副核进行一次注射后，在IGL中可见明显的HRP标记神经元簇。在通过SC尾侧一半的一些切片中，TPB/CFR注射后发现多达七个标记神经元簇。每个簇由3 - 20个细胞组成，所有细胞大小均为小到中等。在也进行了ChAT检测的切片中，发现TPB/CFR病例中的细胞簇与IGL中的ACh斑块精确重叠。此外，投射到IO的SC神经元在ChAT斑块上方和SC的中间白质层（IWL）中形成簇。其他HRP注射均未在SC深层产生任何明显的细胞簇。这些结果首次表明，以大小和投射部位区分的特定细胞群形成与胆碱能传入纤维对上丘的斑块状支配相匹配的簇。这种模块化组织可能对应于也被报道在猫上丘中组织成簇的与扫视相关的细胞。
