Nimchinsky E A, Hof P R, Young W G, Morrison J H
Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, New York 10029, USA.
J Comp Neurol. 1996 Oct 7;374(1):136-60. doi: 10.1002/(SICI)1096-9861(19961007)374:1<136::AID-CNE10>3.0.CO;2-S.
The primate cingulate gyrus contains multiple cortical areas that can be distinguished by several neurochemical features, including the distribution of neurofilament protein-enriched pyramidal neurons. In addition, connectivity and functional properties indicate that there are multiple motor areas in the cortex lining the cingulate sulcus. These motor areas were targeted for analysis of potential interactions among regional specialization, connectivity, and cellular characteristics such as neurochemical profile and morphology. Specifically, intracortical injections of retrogradely transported dyes and intracellular injection were combined with immunocytochemistry to investigate neurons projecting from the cingulate motor areas to the putative forelimb region of the primary motor cortex, area M1. Two separate groups of neurons projecting to area M1 emanated from the cingulate sulcus, one anterior and one posterior, both of which furnished commissural and ipsilateral connections with area M1. The primary difference between the two populations was laminar origin, with the anterior projection originating largely in deep layers, and the posterior projection taking origin equally in superficial and deep layers. With regard to cellular morphology, the anterior projection exhibited more morphologic diversity than the posterior projection. Commissural projections from both anterior and posterior fields originated largely in layer VI. Neurofilament protein distribution was a reliable tool for localizing the two projections and for discriminating between them. Comparable proportions of the two sets of projection neurons contained neurofilament protein, although the density and distribution of the total population of neurofilament protein-enriched neurons was very different in the two subareas of origin. Within a projection, the participating neurons exhibited a high degree of morphologic heterogeneity, and no correlation was observed between somatodendritic morphology and neurofilament protein content. Thus, although the neurons that provide the anterior and posterior cingulate motor projections to area M1 differ morphologically and in laminar origin, their neurochemical profiles are similar with respect to neurofilament protein. This suggests that neurochemical phenotype may be a more important unifying feature for corticocortical projections than morphology.
灵长类动物的扣带回包含多个皮质区域，这些区域可通过多种神经化学特征加以区分，包括富含神经丝蛋白的锥体神经元的分布。此外，连接性和功能特性表明，扣带沟沿线的皮质中存在多个运动区域。这些运动区域旨在分析区域特化、连接性以及细胞特征（如神经化学特征和形态）之间的潜在相互作用。具体而言，将逆行转运染料的皮质内注射和细胞内注射与免疫细胞化学相结合，以研究从扣带运动区域投射到初级运动皮层（M1区）假定前肢区域的神经元。从扣带沟发出的投射到M1区的两组独立神经元，一组在前，一组在后，二者均与M1区形成连合连接和同侧连接。这两组神经元的主要差异在于层状起源，前向投射主要起源于深层，而后向投射在浅层和深层的起源相当。就细胞形态而言，前向投射比后向投射表现出更多的形态多样性。前、后区域的连合投射主要起源于VI层。神经丝蛋白分布是定位这两种投射并对其进行区分的可靠工具。两组投射神经元中含有神经丝蛋白的比例相当，尽管在两个起源子区域中，富含神经丝蛋白的神经元总数的密度和分布差异很大。在一个投射中，参与的神经元表现出高度的形态异质性，并且在树突状形态和神经丝蛋白含量之间未观察到相关性。因此，尽管向M1区提供前扣带运动投射和后扣带运动投射的神经元在形态和层状起源上存在差异，但它们在神经丝蛋白方面的神经化学特征相似。这表明，对于皮质-皮质投射而言，神经化学表型可能比形态更重要，是一个更具统一性的特征。
