Macchi G, Bentivoglio M, Minciacchi D, Molinari M
Rev Neurol (Paris). 1986;142(4):267-82.
Connections ascending to the thalamus. Contrary to classical opinion, all thalamic nuclei receive extrathalamic afferents. Segregation or convergence within a topographically defined nucleus represent two modalities of thalamic afferents. In addition, certain topographically organized thalamic afferents possess "privileged" or primary "targets" in the thalamic nucleus while others possess supplementary "targets" in other thalamic nuclei (see cerebellar, pallidal and spinothalamic projections). Ascending connections from several brain stem structures can converge on the same nucleus or diverge to several thalamic nuclei. Thalamic connections with the telencephalon. Methods for determining axonal transport have demonstrated that all thalamic nuclei, with the exception of the reticular nucleus and the ventral part of the lateral geniculate body, project towards the cerebral cortex. Four nuclear complexes can be recognized in the cat as a function of the different modalities of localization, concentration and lamination of the projections towards the cortex and the central grey nuclei. In general, the thalamocortical connections have reciprocal ipsilateral corticothalamic projections originating in the infragranular layers of the cerebral cortex. The reticular nucleus and the ventral part of the lateral geniculate body, which is not projected to the cerebral cortex, are exceptions. Each cortical area receives a "privileged" connection from a thalamic nucleus and a supplementary connection- from one or several other thalamic nuclei. The "privileged" connections usually pass to the fourth and third layers of the neocortex, and sometimes also to the first layer. In contrast, the supplementary connections pass to different superficial or deep cortical layers. Each nucleus is formed of subunits which possess different hodologic and topographic characteristics as a function of the nucleus considered. Convergence or divergence of thalamocortical and corticothalamic projections on the different thalamic nuclei, as well as the laminar distribution of efferents in the cerebral cortex, are related strictly to the hodologic organization of different cellular subunits constituting the nuclei. Concentration or diffusion of thalamic projections on cerebral cortex is related more to the single or multiple projection of cell populations belonging to a thalamic nucleus than to widespread collateralization of thalamocortical axons.
上行至丘脑的连接。与传统观点相反，所有丘脑核都接受丘脑外传入纤维。在拓扑定义的核内的分离或汇聚代表丘脑传入纤维的两种模式。此外，某些拓扑组织的丘脑传入纤维在丘脑核中有“特权”或主要“靶点”，而其他纤维在其他丘脑核中有辅助“靶点”（见小脑、苍白球和脊髓丘脑束投射）。来自几个脑干结构的上行连接可以汇聚到同一个核，也可以发散到几个丘脑核。丘脑与端脑的连接。确定轴突运输的方法表明，除了网状核和外侧膝状体腹侧部分外，所有丘脑核都向大脑皮质投射。根据投射到皮质和中央灰质核的不同定位、集中和分层模式，在猫中可识别出四个核复合体。一般来说丘脑皮质连接有起源于大脑皮质颗粒下层的相互同侧皮质丘脑投射。网状核和未投射到大脑皮质的外侧膝状体腹侧部分是例外。每个皮质区域接受来自一个丘脑核的“特权”连接和来自一个或几个其他丘脑核的辅助连接。“特权”连接通常到达新皮质的第四和第三层，有时也到达第一层。相比之下，辅助连接到达不同的浅皮质层或深皮质层。每个核由亚单位组成，根据所考虑的核，这些亚单位具有不同的传导和拓扑特征。丘脑皮质和皮质丘脑投射在不同丘脑核上的汇聚或发散，以及大脑皮质中传出纤维的分层分布，与构成核的不同细胞亚单位的传导组织严格相关。丘脑投射在大脑皮质上的集中或扩散更多地与属于丘脑核的细胞群的单投射或多投射有关，而不是与丘脑皮质轴突的广泛侧支有关。
