Porter L L, White E L
J Comp Neurol. 1983 Mar 1;214(3):279-89. doi: 10.1002/cne.902140306.
The afferent and efferent connections of the vibrissal representation within the mouse primary motor cortex (MsI) were identified by using the retrograde transport of horseradish peroxidase (HRP) and the anterograde transport of tritiated amino acids injected into MsI. Following aldehyde perfusion brains were frozen-sectioned at 40 microns and reacted for HRP using the 3-3' diaminobenzidine-cobalt chloride technique of Adams ('77). Alternate HRP reacted sections were processed for autoradiography. HRP-filled pyramidal cell somata and concentrations of developed silver grains above background levels were observed in both the vibrissal area of primary somatosensory cortex (SmI) cortex (i.e., the posteromedial barrel subfield; PMBSF cortex) and in the face region of SmII (area 40). In both regions labeled somata occurred predominantly in cortical layers II-III and V. Autoradiographic label was superimposed over the regions containing labeled somata but exhibited a less distinct laminar organization. A dense reciprocal projection connected the injection site with the homotopic area in contralateral MsI; somata occurred for the most part in layers III and V. Developed silver grains were uniformly dispersed over the area containing labeled cell bodies. HRP-labeled pyramidal somata were noted in contralateral PMBSF cortex, but no silver grains occurred in this region. Reciprocal projections linked MsI cortex with the ipsilateral thalamic nuclei: ventralis pars lateralis (VL) and centralis pars lateralis (CL) and with the zona incerta (ZI). Labeled cell bodies and developed silver grains were more dense in VL than in CL. The ipsilateral striatum and thalamic reticular nucleus (NRT) received afferents from the motor cortex but did not project to it. Thus, the vibrissal area of primary motor cortex is connected with a number of cortical and subcortical structures, each of which has been shown to play a role in motor performance. Identification of the afferent and efferent pathways of MsI cortex will now enable further investigation of the ultrastructural and synaptic organization of the vibrissal area of MsI.
通过使用辣根过氧化物酶（HRP）的逆行运输以及注入初级运动皮层（MsI）的氚化氨基酸的顺行运输，确定了小鼠初级运动皮层（MsI）内触须表征的传入和传出连接。醛灌注后，将大脑切成40微米的冷冻切片，并使用亚当斯（1977年）的3-3'二氨基联苯胺-氯化钴技术对HRP进行反应。交替的HRP反应切片用于放射自显影处理。在初级体感皮层（SmI）的触须区域（即后内侧桶状亚区；PMBSF皮层）和SmII的面部区域（40区）均观察到HRP填充的锥体细胞胞体以及高于背景水平的显影银粒浓度。在这两个区域中，标记的胞体主要出现在皮层的II-III层和V层。放射自显影标记叠加在含有标记胞体的区域上，但层状组织不太明显。密集的相互投射将注射部位与对侧MsI的同位区域相连；胞体大部分出现在III层和V层。显影银粒均匀地分散在含有标记细胞体的区域上。在对侧PMBSF皮层中注意到HRP标记的锥体胞体，但该区域未出现银粒。相互投射将MsI皮层与同侧丘脑核：腹外侧部（VL）和外侧中央部（CL）以及未定带（ZI）相连。VL中的标记细胞体和显影银粒比CL中的更密集。同侧纹状体和丘脑网状核（NRT）接受来自运动皮层的传入纤维，但不向其投射。因此，初级运动皮层的触须区域与许多皮层和皮层下结构相连，每个结构都已被证明在运动表现中起作用。确定MsI皮层的传入和传出通路现在将有助于进一步研究MsI触须区域的超微结构和突触组织。
