Boyden Edward S, Katoh Akira, Raymond Jennifer L
Department of Neurobiology, Stanford University, Stanford, California 94305, USA.
Annu Rev Neurosci. 2004;27:581-609. doi: 10.1146/annurev.neuro.27.070203.144238.
The cerebellum is an evolutionarily conserved structure critical for motor learning in vertebrates. The model that has influenced much of the work in the field for the past 30 years suggests that motor learning is mediated by a single plasticity mechanism in the cerebellum: long-term depression (LTD) of parallel fiber synapses onto Purkinje cells. However, recent studies of simple behaviors such as the vestibulo-ocular reflex (VOR) indicate that multiple plasticity mechanisms contribute to cerebellum-dependent learning. Multiple plasticity mechanisms may provide the flexibility required to store memories over different timescales, regulate the dynamics of movement, and allow bidirectional changes in movement amplitude. These plasticity mechanisms must act in combination with appropriate information-coding strategies to equip motor-learning systems with the ability to express learning in correct contexts. Studies of the patterns of generalization of motor learning in the VOR provide insight about the coding of information in neurons at sites of plasticity. These principles emerging from studies of the VOR are consistent with results concerning more complex behaviors and thus may reflect general principles of cerebellar function.
小脑是脊椎动物中对运动学习至关重要的一个进化上保守的结构。在过去30年里，该领域的许多研究工作都受其影响的模型表明，运动学习是由小脑中单一的可塑性机制介导的：平行纤维与浦肯野细胞突触的长时程抑制（LTD）。然而，最近对诸如前庭眼反射（VOR）等简单行为的研究表明，多种可塑性机制参与了依赖小脑的学习。多种可塑性机制可能提供在不同时间尺度上存储记忆、调节运动动态以及允许运动幅度双向变化所需的灵活性。这些可塑性机制必须与适当的信息编码策略相结合，以使运动学习系统具备在正确情境中表达学习的能力。对VOR中运动学习泛化模式的研究为可塑性位点神经元中的信息编码提供了见解。从VOR研究中得出的这些原理与关于更复杂行为的结果一致，因此可能反映了小脑功能的一般原理。
