Department of Neurobiology, The Weizmann Institute of Science Rehovot, Israel.
Front Neuroanat. 2008 Sep 12;2:4. doi: 10.3389/neuro.05.004.2008. eCollection 2008.
The ventral posteromedial thalamic nucleus (VPM) of the rat contains at least two major vibrissa-representing compartments: the dorsomedial (VPMdm), which belongs to the lemniscal afferent pathway, and the ventrolateral (VPMvl), which belongs to the extralemniscal afferent pathway. Although input-output projections and functional characteristics that distinguish these two compartments were recently clarified, a comprehensive structural analysis of these compartments and the border between them was lacking. This paper addresses structural and functional relationships between the VPMdm and VPMvl. We found that the size of the VPM is almost constant across individual rats. Next, we computed a canonical map of the VPM in the oblique plane, where structural borders are best visualized. Using the canonical map, and sequential slices cut in oblique and coronal planes, we determined the border between the VPMdm and VPMvl in the standard coronal plane, and verified it with in vivo extracellular recordings. The position of the border between these two vibrissal sub-nuclei changes along the rostrocaudal extent within the VPM due to the relative sizes of these sub-nuclei at any point. The border between the VPMdm and VPMvl, which was revealed by this technique, can now be included in atlases of the rat brain and should facilitate experimental correlation of tactile functions with thalamic regions.
大鼠腹后内侧丘脑核（VPM）至少包含两个主要的触须代表区：背内侧（VPMdm），属于伦尼克传入途径，和腹外侧（VPMvl），属于非伦尼克传入途径。尽管最近已经阐明了区分这两个隔室的输入-输出投射和功能特征，但对这些隔室及其边界的综合结构分析仍缺乏。本文探讨了 VPMdm 和 VPMvl 之间的结构和功能关系。我们发现，VPM 的大小在个体大鼠之间几乎保持不变。接下来，我们在斜平面上计算了 VPM 的规范图，在这个平面上可以最好地观察到结构边界。使用规范图和在斜平面和冠状平面上连续切片，我们确定了 VPMdm 和 VPMvl 在标准冠状平面上的边界，并通过在体外记录进行了验证。由于在任何一点这些亚核的相对大小，这两个触须亚核之间的边界在 VPM 的前后方向上发生变化。通过这项技术揭示的 VPMdm 和 VPMvl 之间的边界现在可以包含在大鼠脑图谱中，并应有助于将触觉功能与丘脑区域的实验相关性。
