Masuda Naoki, Amari Shun-ichi
Amari Research Unit, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
J Comput Neurosci. 2008 Apr;24(2):137-56. doi: 10.1007/s10827-007-0045-7. Epub 2007 Jul 7.
There is a debate regarding whether motor memory is stored in the cerebellar cortex, or the cerebellar nuclei, or both. Memory may be acquired in the cortex and then be transferred to the cerebellar nuclei. Based on a dynamical system modeling with a minimal set of variables, we theoretically investigated possible mechanisms of memory transfer and consolidation in the context of vestibulo-ocular reflex learning. We tested different plasticity rules for synapses in the cerebellar nuclei and took robustness of behavior against parameter variation as the criterion of plausibility of a model variant. In the most plausible scenarios, mossy-fiber nucleus-neuron synapses or Purkinje-cell nucleus-neuron synapses are plastic on a slow time scale and store permanent memory, whose content is passed from the cerebellar cortex storing transient memory. In these scenarios, synaptic strengths are potentiated when the mossy-fiber afferents to the nuclei are active during a pause in Purkinje-cell activities. Furthermore, assuming that mossy fibers create a limited variety of signals compared to parallel fibers, our model shows partial memory transfer from the cortex to the nuclei.
关于运动记忆是存储在小脑皮质、小脑核团还是两者中，存在一场争论。记忆可能在皮质中获取，然后转移到小脑核团。基于一个具有最少变量集的动态系统模型，我们从理论上研究了前庭眼反射学习背景下记忆转移和巩固的可能机制。我们测试了小脑核团中突触的不同可塑性规则，并将行为对参数变化的稳健性作为模型变体合理性的标准。在最合理的情况下，苔藓纤维 - 核神经元突触或浦肯野细胞 - 核神经元突触在缓慢的时间尺度上具有可塑性并存储永久记忆，其内容从存储短暂记忆的小脑皮质传递而来。在这些情况下，当苔藓纤维传入核团的信号在浦肯野细胞活动暂停期间活跃时，突触强度会增强。此外，假设与平行纤维相比，苔藓纤维产生的信号种类有限，我们的模型显示了从皮质到核团的部分记忆转移。
