Brown I E, Bower J M
Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
J Comp Neurol. 2001 Jan 1;429(1):59-70. doi: 10.1002/1096-9861(20000101)429:1<59::aid-cne5>3.0.co;2-3.
We have examined the spatial relationship between the mossy fiber and climbing fiber projections to crus IIa in the lateral hemispheres of the rat cerebellum. Experiments were performed in ketamine/xylazine anesthetized rats using extracellular recordings and high-density micromapping techniques. Responses were elicited using small, tactile stimuli applied to the perioral and forelimb regions at a rate of 0.5 Hz. In our first series of experiments we demonstrate that the primary (i.e., strongest) receptive field for a single Purkinje cell's complex spike is similar to the primary receptive field of the granule cells immediately subjacent to that Purkinje cell. In our second series of experiments we demonstrate that the granule cell region most strongly activated by a particular peripheral stimulus is immediately subjacent to the Purkinje cells whose complex spikes are also activated most strongly by the same stimulus. The region of climbing fibers activated by a localized peripheral stimulus is "patchy"; it clearly does not conform to the notion of a continuous microzone. These results support original observations first reported in the 1960s using evoked potential recording techniques that the mossy fiber and climbing fiber pathways converge in cerebellar cortex. However, we extend this earlier work to show that the two pathways converge at the level of single Purkinje cells. Many cerebellar theories assume that mossy fiber and climbing fiber pathways carry information from different peripheral locations or different modalities to cerebellar Purkinje cells. Our results appear to contradict this basic assumption for at least the tactile regions of the lateral hemispheres.
我们研究了大鼠小脑外侧半球中苔藓纤维和攀爬纤维向IIa小叶投射之间的空间关系。实验在氯胺酮/赛拉嗪麻醉的大鼠身上进行，采用细胞外记录和高密度微映射技术。通过以0.5赫兹的频率向口周和前肢区域施加小的触觉刺激来引发反应。在我们的第一系列实验中，我们证明单个浦肯野细胞复合锋电位的主要（即最强的）感受野与紧邻该浦肯野细胞的颗粒细胞的主要感受野相似。在我们的第二系列实验中，我们证明被特定外周刺激最强烈激活的颗粒细胞区域紧邻其复合锋电位也被同一刺激最强烈激活的浦肯野细胞。由局部外周刺激激活的攀爬纤维区域是“斑片状的”；它显然不符合连续微区的概念。这些结果支持了20世纪60年代首次使用诱发电位记录技术报道的原始观察结果，即苔藓纤维和攀爬纤维通路在小脑皮质汇聚。然而，我们扩展了这项早期工作，以表明这两条通路在单个浦肯野细胞水平上汇聚。许多小脑理论假设苔藓纤维和攀爬纤维通路将来自不同外周位置或不同感觉模态的信息传递给小脑浦肯野细胞。至少对于外侧半球的触觉区域，我们的结果似乎与这一基本假设相矛盾。
