Herrup K, Shojaeian-Zanjani H, Panzini L, Sunter K, Mariani J
Alzheimer Research Laboratory, Case Western Reserve University, Cleveland, OH 44106, USA.
Brain Res Dev Brain Res. 1996 Oct 23;96(1-2):28-35. doi: 10.1016/0165-3806(96)00069-7.
During a defined critical period of development, if the target of a neuronal population is removed, there is a massive decrease in the number of neurons that survive into adulthood. Previous studies have found that source neuron number is a strictly linear function of target size. The current work extends these observations to the inferior olive-->Purkinje cell projection. Three distinct model systems have been used: (i) lurcher<-->wild-type aggregation chimeras, (ii) staggerer<-->wild-type chimeras and (iii) naturally occurring polymorphisms in Purkinje cell number found in different inbred mouse strains. Total neuron numbers were counted in the inferior olive and plotted as a function of the number of Purkinje cells in the contralateral cerebellar cortex. In lurcher mutants and chimeras, the relationship between these values is well described by a straight line. This suggests that, like the granule-->Purkinje cell circuit, the olive-->Purkinje cell circuit uses a linear algorithm to achieve a numerical balance. The results from the two other model systems were not as clear cut. In the staggerer chimeras, we found only a rough correlation between neuron and target numbers and in the inbred strains there was no discernible relationship at all. These findings indicate that in the final analysis, there are multiple factors involved in the determination of the number of olive cells surviving into adulthood. The potential contribution of sustaining collaterals and afferent inputs is discussed as well as the possible existence of different subcircuits of olivocerebellar connections, each with its own numerical matching function.
在发育的特定关键时期，如果去除神经元群体的靶标，那么存活至成年期的神经元数量会大幅减少。先前的研究发现，源神经元数量是靶标大小的严格线性函数。当前的研究将这些观察结果扩展至下橄榄核→浦肯野细胞投射。已使用了三种不同的模型系统：（i）蹒跚突变体→野生型聚集嵌合体，（ii）蹒跚突变体→野生型嵌合体，以及（iii）在不同近交系小鼠中发现的浦肯野细胞数量的自然多态性。对下橄榄核中的神经元总数进行计数，并将其绘制为对侧小脑皮质中浦肯野细胞数量的函数。在蹒跚突变体和嵌合体中，这些值之间的关系可用一条直线很好地描述。这表明，与颗粒细胞→浦肯野细胞回路一样，橄榄核→浦肯野细胞回路使用线性算法来实现数量平衡。另外两个模型系统的结果并不那么明确。在蹒跚突变体嵌合体中，我们仅发现神经元数量与靶标数量之间存在大致的相关性，而在近交系中则完全没有可辨别的关系。这些发现表明，归根结底，有多种因素参与决定存活至成年期的橄榄核细胞数量。文中讨论了持续侧支和传入输入的潜在贡献，以及橄榄小脑连接不同子回路的可能存在，每个子回路都有其自身的数量匹配功能。
