Yen C T, Conley M, Jones E G
J Neurosci. 1985 May;5(5):1316-38. doi: 10.1523/JNEUROSCI.05-05-01316.1985.
Neurons in the thalamic ventral posterior (VB) nucleus of the cat were investigated by extracellular and intracellular recording and by anatomical methods involving either the retrograde transport of horseradish peroxidase (HRP) or the intracellular injection of HRP. Two morphological types of neurons could be detected by retrograde labeling from small injections of HRP in the internal capsule adjacent to VB. These two and one other type, judged to be an interneuron, could also be identified by intracellular staining. Type I cells are large, have thick proximal dendrites which branch in a tuft-like manner, and thick, rapidly conducting axons. They possess few or no dendritic appendages. Type II cells are smaller and have slender proximal dendrites which branch dichotomously and thin, slower conducting axons. Those injected intracellularly are covered in fine, hair-like dendritic appendages. Type III cells are small and have thin processes that give rise to many bulbous dilatations and no obvious axon. Type I and type II cells give off slender axon collaterals in the thalamic reticular nucleus but not in VB. Examples of both types of cell could be antidromically activated from the somatic sensory cortex. Type I and type II cells recovered histologically after intracellular recording included examples of most types of receptive field, including several forms of cutaneous and deep fields, as classified by us in a parallel intra- and extracellular study of unit responses. All but one type I cell, however, responded in a transient manner to peripheral stimulation. The remaining type I cell and all members of an admittedly small sample of type II cells responded in a sustained manner. The sample of recovered interneurons and of units that could not be driven antidromically from the cerebral cortex suggested that they, too, included all receptive field types. We conclude that submodality specificity in VB is not represented by morphological specificity in thalamocortical relay cells or interneurons. Some other functional parameter, such as tonic or phasic responsiveness, may be more obviously correlated with relay cell morphology.
通过细胞外和细胞内记录以及采用辣根过氧化物酶（HRP）逆行运输或HRP细胞内注射的解剖学方法，对猫丘脑腹后（VB）核中的神经元进行了研究。通过在VB附近的内囊中小剂量注射HRP进行逆行标记，可以检测到两种形态类型的神经元。这两种类型以及另一种被判断为中间神经元的类型，也可以通过细胞内染色来识别。I型细胞较大，近端树突较粗，呈簇状分支，轴突粗且传导速度快。它们几乎没有或没有树突附属物。II型细胞较小，近端树突细长，呈二叉状分支，轴突细且传导速度慢。那些细胞内注射的II型细胞覆盖着细小的毛发状树突附属物。III型细胞较小，有细的突起，这些突起产生许多球状膨大，没有明显的轴突。I型和II型细胞在丘脑网状核中发出细长的轴突侧支，但在VB中不发出。两种类型的细胞都可以从躯体感觉皮层进行逆向激活。细胞内记录后经组织学鉴定的I型和II型细胞包括了大多数类型的感受野实例，包括我们在对单位反应进行的平行细胞内和细胞外研究中分类的几种皮肤和深部感受野形式。然而，除了一个I型细胞外，所有细胞对外周刺激的反应都是短暂的。其余的I型细胞以及一个公认数量较少的II型细胞样本的所有成员的反应都是持续的。经组织学鉴定的中间神经元样本以及无法从大脑皮层进行逆向驱动的单位表明，它们也包括所有类型的感受野。我们得出结论，VB中的亚模态特异性在丘脑皮质中继细胞或中间神经元中不是由形态特异性来体现的。一些其他功能参数，如紧张性或相位性反应性，可能与中继细胞形态有更明显的相关性。
