Cohen D, Yarom Y
Department of Neurobiology, Life Sciences Institute and Center for Neural Computation, Hebrew University, Jerusalem 91904, Israel.
Proc Natl Acad Sci U S A. 1998 Dec 8;95(25):15032-6. doi: 10.1073/pnas.95.25.15032.
The discrepancy between the structural longitudinal organization of the parallel-fiber system in the cerebellar cortex and the functional mosaic-like organization of the cortex has provoked controversial theories about the flow of information in the cerebellum. We address this issue by characterizing the spatiotemporal organization of neuronal activity in the cerebellar cortex by using optical imaging of voltage-sensitive dyes in isolated guinea-pig cerebellum. Parallel-fiber stimulation evoked a narrow beam of activity, which propagated along the parallel fibers. Stimulation of the mossy fibers elicited a circular, nonpropagating patch of synchronized activity. These results strongly support the hypothesis that a beam of parallel fibers, activated by a focal group of granule cells, fails to activate the Purkinje cells along most of its length. It is thus the ascending axon of the granule cell, and not its parallel branches, that activates and defines the basic functional modules of the cerebellar cortex.
小脑皮质中平行纤维系统的结构纵向组织与皮质的功能镶嵌样组织之间的差异引发了关于小脑信息流动的争议性理论。我们通过在分离的豚鼠小脑中使用电压敏感染料的光学成像来表征小脑皮质中神经元活动的时空组织，从而解决这个问题。平行纤维刺激引发了一束狭窄的活动，该活动沿着平行纤维传播。苔藓纤维刺激引发了一个圆形的、不传播的同步活动斑块。这些结果有力地支持了这样一种假设，即由一组局部颗粒细胞激活的一束平行纤维在其大部分长度上未能激活浦肯野细胞。因此，激活并定义小脑皮质基本功能模块的是颗粒细胞的上升轴突，而不是其平行分支。
