Redefining cerebellar ataxia in degenerative ataxias: lessons from recent research on cerebellar systems.
Redefining cerebellar ataxia in degenerative ataxias: lessons from recent research on cerebellar systems.
复制标题
重新定义退行性共济失调中的小脑共济失调：最近小脑系统研究的教训。
DOI：
10.1136/jnnp-2013-307225
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Onodera O
中科院分区：
文献类型：
--
作者：
Tada M;Nishizawa M;Onodera O
我们对小脑系统神经生理功能的理解的最新进展表明，参与退行性共济失调的每个区域都有不同的贡献。为了调节随意运动，小脑在其神经回路内形成内部模型，模仿感觉运动系统和外部环境中物体的行为。小脑形成两种不同的内部模型：正向模型和反向模型。正向模型由脑桥小脑系统传递的输出复制信号形成，并推导出行动的估计后果。逆模型描述了实现目标的运动命令序列。在运动学习过程中，我们通过将正向模型的动作估计结果与逆向模型产生的动作的实际结果进行比较来改进内部模型。小脑的功能包括内部模型的形成、存储和选择。考虑到小脑系统的神经生理学特性，我们根据涉及的系统将退行性共济失调分为四种类型：浦肯野细胞、皮质桥小脑系统、脊髓小脑系统和小脑深部核团。关于它们各自对内部模型的贡献，我们推测浦肯野细胞的丢失导致内部模型的畸形，而传入系统、皮质桥小脑系统或脊髓小脑系统的干扰导致正确的内部模型的错误选择。了解每种退行性共济失调中共济失调的病理生理学特性有助于开发评估共济失调的新方法。
Recent advances in our understanding of neurophysiological functions in the cerebellar system have revealed that each region involved in degenerative ataxias contributes differently. To regulate voluntary movements, the cerebellum forms internal models within its neural circuits that mimic the behaviour of the sensorimotor system and objects in the external environment. The cerebellum forms two different internal models: forward and inverse. The forward model is formed by efference copy signals conveyed by the corticopontocerebellar system, and it derives the estimated consequences for action. The inverse model describes sequences of motor commands to accomplish an aim. During motor learning, we improve internal models by comparing the estimated consequence of an action from the forward model with the actual consequence of the action produced by the inverse model. The functions of the cerebellum encompass the formation, storage and selection of internal models. Considering the neurophysiological properties of the cerebellar system, we have classified degenerative ataxias into four types depending on which system is involved: Purkinje cells, the corticopontocerebellar system, the spinocerebellar system and the cerebellar deep nuclei. With regard to their respective contributions to the internal models, we speculate that loss of Purkinje cells leads to malformation of the internal models, whereas disturbance of the afferent system, corticopontocerebellar system or spinocerebellar system leads to mis-selection of the proper internal model. An understanding of the pathophysiological properties of ataxias in each degenerative ataxia enables the development of new methods to evaluate ataxias.