Höhl-Abrahão J C, Creutzfeldt O D
Departamento de Ciencias Fisiologicas, Universidade de Brasilia, DF.
Exp Brain Res. 1991;87(2):283-94. doi: 10.1007/BF00231845.
The general topographical organization of the thalamo-cortical projection of two rodents, the Siberian hamster (Phodopus sungorus) and the Guinea pig (Cavia aperta) was investigated with the HRP-method and compared with that of the new world primate marmoset (Cal-lithrix jacchus) as shown in a companion study by Brysch et al. (1990). HRP was injected into various regions of the cortex in different animals and hemispheres, and plots were made of the retrogradely stained thalamic projection neurons. The thalamocortical projection is virtually identical in both rodent species. It is topological throughout in that nearby cortical injections label nearby, though overlapping cell groups in the thalamus. Cortical injections in a rostro-caudal progression labelled thalamic projection zones on top of each other, layered like tiles on a roof or fish scales, beginning in the rostromedial and ending in the caudo-dorsal thalamus. The progression vector of thalamic zones projecting successively from more rostral to more caudal cortical zones is twisted and turns from a predominantly mediolateral direction in the anterior thalamus to an essentially ventro-dorsal direction in the posterior thalamus In the marmoset, the thalamo-cortical topography follows the same topological rule, with the exception of the lateral geniculate body which is translocated latero-ventrally and separated from the rest of the thalamus as in all primates. This suggests a general thalamo-cortical mapping rule common to all mammals which can be related to gradients and timing of cell birth in the thalamus. It is proposed that this mapping rule is the consequence of successive appositions of neurons in the medio-ventral thalamus during ontogenetic development.
利用辣根过氧化物酶（HRP）法研究了两种啮齿动物——西伯利亚仓鼠（Phodopus sungorus）和豚鼠（Cavia aperta）丘脑-皮质投射的一般拓扑组织，并与新大陆灵长类动物狨猴（Callithrix jacchus）的丘脑-皮质投射进行了比较，如Brysch等人（1990年）在一项配套研究中所示。将HRP注射到不同动物和半球的皮质不同区域，并绘制逆行标记的丘脑投射神经元图。两种啮齿动物的丘脑-皮质投射实际上是相同的。它在整个过程中都是拓扑性的，即附近的皮质注射标记丘脑附近但重叠的细胞群。沿前后方向进行的皮质注射标记的丘脑投射区相互叠加，像屋顶上的瓦片或鱼鳞一样分层，从丘脑的吻内侧开始，到丘脑的尾背侧结束。从更靠前的皮质区依次投射到更靠后的皮质区的丘脑区的进展向量是扭曲的，从前丘脑的主要中外侧方向转向后丘脑的基本腹背方向。在狨猴中，丘脑-皮质拓扑遵循相同的拓扑规则，但外侧膝状体除外，外侧膝状体如所有灵长类动物一样向腹外侧移位并与丘脑的其余部分分离。这表明所有哺乳动物都有一个共同的丘脑-皮质映射规则，该规则可能与丘脑中细胞出生的梯度和时间有关。有人提出，这种映射规则是个体发育过程中丘脑腹内侧神经元连续并置的结果。
