Department of Anatomy, College of Medicine, Konkuk University, Hwayang-dong, Gwangjin-gu, Seoul, Korea.
Brain Res. 2010 Jun 8;1336:30-45. doi: 10.1016/j.brainres.2010.03.100. Epub 2010 Apr 8.
The primary goal of this anatomical study was to examine in the rat whether cholinergic neurons provide axon collaterals to whisker-related, sensorimotor regions at cortical, thalamic, and brainstem levels, using a combined method of retrograde tracing and choline acetyltransferase (ChAT) immunostaining. First, when injections were made at primary sensory (S1) barrel field/primary whisker motor (M1) cortices, cholinergic neurons with dual projections were observed in the basal nucleus of Meynert (BM), mainly at middle level; the projection was almost exclusively ipsilateral (99%+/-0.7%, n=6). Second, following unilateral injections of tracers into ventroposteromedial (VPM) barreloids/ventrolateral (VL) thalamic nucleus, dual-projecting cells were observed in the mesopontine tegmental complex including the pedunculopontine tegmental (PTg) and laterodorsal tegmental (LDTg) nuclei, mainly at rostral to middle levels; the projection exhibited ipsilateral dominance, i.e., 67%+/-1.3% (n=6) for the PTg and 64%+/-1.2% (n=6) for the LDTg. Finally, when injections were made at whisker-related, principal sensory trigeminal (Pr5)/facial motor (Mo7) nuclei, a relatively small number of labeled neurons were observed in the PTg and the LDTg at middle to caudal levels; within LDTg, labeled cells occupied the ventral portion of the dorsal LDTg as well as the ventral LDTg (LDTgV). This projection exhibited contralateral preponderance, i.e., 67%+/-2.0% (n=6) for the PTg and 69%+/-3.2% (n=6) for the LDTg. Taken together, the present observations demonstrated that each division of the BM, PTg, and LDTg possessed a differential functional organization with respect to its collateral projection to whisker-related sensorimotor targets, suggesting that the cholinergic projection might play a modulatory role in vibrissal sensorimotor integration, which allows the guidance of behavioral action essential for the survival of the animal.
本解剖学研究的主要目的是在大鼠中检验胆碱能神经元是否在皮质、丘脑和脑干水平向与胡须相关的感觉运动区域提供轴突侧支，采用逆行追踪和胆碱乙酰转移酶（ChAT）免疫染色的联合方法。首先，当在初级感觉（S1）桶状皮层/初级胡须运动（M1）皮层进行注射时，在梅内尔特基底核（BM）中观察到具有双重投射的胆碱能神经元，主要位于中间水平；投射几乎完全是同侧的（99%+/-0.7%，n=6）。其次，在单侧注射示踪剂到腹后内侧（VPM）桶状核/腹外侧（VL）丘脑核后，在包括脚桥核被盖（PTg）和外侧背盖核（LDTg）在内的中脑被盖腹侧复合体中观察到具有双重投射的细胞，主要位于中到前水平；投射表现出同侧优势，即对于 PTg 为 67%+/-1.3%（n=6），对于 LDTg 为 64%+/-1.2%（n=6）。最后，当在与胡须相关的、主要感觉三叉神经（Pr5）/面部运动（Mo7）核进行注射时，在中到尾水平的 PTg 和 LDTg 中观察到相对较少的标记神经元；在 LDTg 中，标记细胞占据背外侧 LDTg 的腹侧部分以及腹外侧 LDTg（LDTgV）。该投射表现出对侧优势，即对于 PTg 为 67%+/-2.0%（n=6），对于 LDTg 为 69%+/-3.2%（n=6）。综上所述，本研究观察结果表明，BM、PTg 和 LDTg 的每个分支都具有与胡须相关的感觉运动靶标侧支投射的不同功能组织，表明胆碱能投射可能在胡须感觉运动整合中发挥调节作用，这使得行为动作的指导对于动物的生存至关重要。
