Blomqvist A, Zhang E T, Craig A D
Division of Cell Biology, Department of Biomedicine and Surgery, Faculty of Health Sciences, University of Linköping, Sweden.
Brain. 2000 Mar;123 Pt 3:601-19. doi: 10.1093/brain/123.3.601.
Previous studies in the macaque monkey have identified a thalamic nucleus, the posterior portion of the ventral medial nucleus (VMpo), as a dedicated lamina I spinothalamocortical relay for pain and temperature sensation. The dense plexus of calbindin-immunoreactive fibres that characterizes VMpo in primates enables its homologue to be identified in the human thalamus by immunohistochemical labelling for calbindin. We have now analysed in detail the cytoarchitectonic characteristics of VMpo and its relationship with immunoreactivity for calbindin, substance P and calcitonin gene-related peptide (CGRP) in the human thalamus. The area in the posterolateral thalamus in which dense calbindin-immunoreactive fibre terminations are present coincides nearly completely with a distinct region that contains small to medium-sized cells with round or oval shapes that are aggregated in clusters separated by cell sparse areas. This region, which we identify as VMpo, is located posteromedial to the ventral posterior lateral (VPL) and ventral posterior medial (VPM) nuclei, ventral to the anterior pulvinar and centre médian nuclei, lateral to the limitans and parafascicular nuclei and dorsal to the medial geniculate nucleus. Calbindin-immunoreactive fibres enter VMpo from the spinal lemniscus and form large patches of dense terminal-like staining over clusters of VMpo neurons. A few of these clusters also display terminal-like substance P labelling. Small bursts of CGRP staining are intercalated between the calbindin-labelled clusters, but there is little or no overlap between these two markers. CGRP immunoreactivity is also present over small, non-clustered neurons in the calbindin-negative area that separates VMpo from the VPL and VPM nuclei, which we denote as the posterior nucleus (Po). These observations provide a concise description of VMpo in the human thalamus. Further, they suggest that the lamina I spinothalamic tract fibres (represented by calbindin and probably also substance P immunoreactivity) and vagal-solitary-parabrachial afferents (represented by CGRP immunoreactivity) form closely related, but separate, termination fields that can be considered to represent different aspects of enteroceptive information regarding the physiological status of the tissues and organs of the body. The location of VMpo and the adjacent Po fits with clinical descriptions of the thalamic area from which pain, temperature and visceral sensations can be evoked by microstimulation, and where nociceptive and thermoreceptive neurons have been recorded in humans. It also corresponds to the area in which infarcts cause analgesia and thermoanaesthesia and can lead to the paradoxical development of central pain.
先前对猕猴的研究已确定一个丘脑核团，即腹内侧核（VMpo）的后部，是专门负责痛觉和温度觉的I层脊髓丘脑皮质中继站。灵长类动物中VMpo所特有的钙结合蛋白免疫反应性纤维的密集丛，使得通过对钙结合蛋白进行免疫组织化学标记，能在人类丘脑中识别出其同源物。我们现在详细分析了VMpo的细胞构筑特征及其与人丘脑钙结合蛋白、P物质和降钙素基因相关肽（CGRP）免疫反应性的关系。丘脑后外侧存在密集钙结合蛋白免疫反应性纤维终末的区域，几乎完全与一个独特区域重合，该区域包含圆形或椭圆形的中小型细胞，这些细胞聚集形成由细胞稀疏区域分隔的簇。我们将这个区域确定为VMpo，它位于腹后外侧核（VPL）和腹后内侧核（VPM）的后内侧，前丘脑枕和中央中核的腹侧，界核和束旁核的外侧，内侧膝状体核的背侧。钙结合蛋白免疫反应性纤维从脊髓丘系进入VMpo，并在VMpo神经元簇上形成大片密集的终末样染色。其中一些簇也显示终末样P物质标记。CGRP染色的小簇穿插在钙结合蛋白标记的簇之间，但这两种标记物之间几乎没有重叠。CGRP免疫反应性也存在于将VMpo与VPL和VPM核分隔开的钙结合蛋白阴性区域中的小的、非簇状神经元上，我们将该区域称为后核（Po）。这些观察结果对人类丘脑中的VMpo进行了简要描述。此外，它们表明I层脊髓丘脑束纤维（以钙结合蛋白以及可能还有P物质免疫反应性为代表）和迷走神经 - 孤束核 -臂旁传入纤维（以CGRP免疫反应性为代表）形成了密切相关但又相互分离的终末场，可以认为它们代表了关于身体组织和器官生理状态的内感受信息的不同方面。VMpo和相邻的Po的位置与丘脑区域的临床描述相符，在该区域通过微刺激可诱发疼痛、温度觉和内脏感觉，并且在人类中已记录到伤害性感受和温度感受神经元。它也对应于梗死导致镇痛和温度觉缺失并可导致中枢性疼痛反常发展的区域。
