Sakai S T
J Comp Neurol. 1982 Jan 20;204(3):238-52. doi: 10.1002/cne.902040304.
The purpose of this study was to determine the pattern of thalamic projections of the primary motor cortex (MI) in the raccoon, a carnivore species noted for neural specialization of sensorimotor function. Following electrophysiological identification of circumscribed regions of MI, injections of horseradish peroxidase (HRP) or HRP combined with tritiated amino acids were made in 15 animals. Labeled thalamic cells were found predominantly in the ventral lateral nucleus (VL). For a given cortical injection site within MI, labeled neurons in VL formed a crescent-shaped band which extended in a dorsoventral direction when viewed in coronal sections. These bands were topographically organized. Following an injection of the MI hindlimb area in the medial part of the posterior cruciate gyrus, both retrogradely labeled neurons and anterograde label formed a thin band at the lateral edge of VL while an injection of the MI face area in the lateral part of the anterior cruciate gyrus resulted in both anterograde and retrograde label in medial VL and the principal division of the ventromedial nucleus (VMp). An injection of the MI forepaw area localized to the rostral and central part of the posterior cruciate gyrus resulted in a band of labeled neurons occupying the dorsal extent of VL and continuing into the ventrolateral aspect of the ventral anterior nucleus (VA). In contrast, an injection of the MI forepaw area which was localized to the caudal extent of the posterior cruciate gyrus resulted in a wide and diffuse band of labeled neurons and anterograde label in the ventral portion of VL. All injection of MI produced cell labeling in the paracentral nucleus (PC) and the central lateral nucleus (CL) of the intralaminar group. These results demonstrate that VL is the primary thalamic dependency of MI in the raccoon. Labeled cells were not observed in the ventrobasal complex. The MI pattern of thalamic connectivity observed in the present study suggests that while differences exist in the regional specialization of sensorimotor structures among species, there appears to be little variation in the overall organization of thalamocortical relations.
本研究的目的是确定浣熊初级运动皮层（MI）的丘脑投射模式，浣熊是一种以感觉运动功能的神经特化而闻名的食肉动物。在对MI的限定区域进行电生理鉴定后，对15只动物注射了辣根过氧化物酶（HRP）或HRP与氚化氨基酸的混合物。标记的丘脑细胞主要见于腹外侧核（VL）。对于MI内给定的皮层注射部位，VL中的标记神经元形成一个新月形带，在冠状切片中观察时，该带沿背腹方向延伸。这些带呈拓扑组织。在注射后十字回内侧部分的MI后肢区域后，逆行标记的神经元和顺行标记在VL的外侧边缘形成一条细带，而在前十字回外侧部分注射MI面部区域则导致内侧VL和腹内侧核主部（VMp）出现顺行和逆行标记。注射到后十字回嘴侧和中央部分的MI前爪区域导致一条标记神经元带占据VL的背侧范围，并延伸到腹前核（VA）的腹外侧。相反，注射到后十字回尾侧部分的MI前爪区域导致VL腹侧有一条宽而弥散的标记神经元带和顺行标记。所有MI注射均在板内核群的中央旁核（PC）和中央外侧核（CL）产生细胞标记。这些结果表明，VL是浣熊MI的主要丘脑依赖区。在腹侧基底复合体中未观察到标记细胞。本研究中观察到的MI丘脑连接模式表明，虽然不同物种间感觉运动结构的区域特化存在差异，但丘脑皮质关系的整体组织似乎变化不大。
