The role of the cerebellum in the control of saccades as a window into neural mechanisms of movement optimization

我们早些时候对小脑的一个独特部分--动眼蠕虫(OMV)的研究表明，OMV的神经元机制进行的信息处理是两种互补类型的目标定向眼动--扫视和平稳追逐--运动学几乎瞬时调节(短期动眼学习)的主要底物，这是操作错误所要求的。我们在第一个资助期的实验表明，OMV部署了一个和相同的输出神经元(浦肯野细胞)来控制两种类型的眼动，而不会危及保证基于学习的变化是特定于眼动类型的需要。考虑到眼跳和平稳追逐的运动学特征截然不同，混合浦肯野细胞的部署令人惊讶。这些发现对浦肯野细胞树突树整合扫视和平滑追踪相关信号有一定意义，并通常限制了所涉及的各种神经元元件的连接。关于眼跳和平稳追踪之间短期学习迁移的第二个实验进一步支持了这样一个观点，即目标导向眼动的短期学习的主要生物学功能是补偿认知疲劳，我们使用这个术语是为了捕捉由于运动目标的主观价值的变化而导致的眼动运动学的变化，而不一定排除其他因素，如注意力。对于第二个资助期，我们建议进行实验，试图通过将运动和运动目标的主观价值信息转化为眼跳的纠正控制信号，来批判性地检验OMV在补偿认知疲劳方面发挥核心作用的假设。

Our earlier work on the oculomotor vermis (OMV), a distinct part of the cerebellum, could establish that information processing by the neuronal machinery of the OMV is the major substrate of the almost instantaneous adjustment (short-term oculomotor learning) of the kinematics of the two complementary types of goal-directed eye movements, saccades and smooth pursuit, demanded by performance errors. Our experiments in the first funding period demonstrate that the OMV deploys the one and the same output neurons (Purkinje cells) to control both types of eye movements without jeopardizing the need to warrant that learning-based changes are eye movement type specific. The deployment of hybrid Purkinje cells is surprising in view of the very different kinematic profiles of saccades and smooth pursuit. These findings have implications for the integration of saccade and smooth pursuit-related signals by Purkinje-cell dendritic trees and in general constrain the wiring of the various neuronal elements involved. A second line of experiments on the transfer of short-term learning between saccades and smooth-pursuit lends further support to the notion that the major biological function of short-term learning of goal-directed eye movements is the compensation of cognitive fatigue, a term we use in order to capture changes of eye movement kinematics due to changes of the subjective value of movement goals without necessarily excluding other factors such as attention. For the second funding period we suggest experiments that will try to critically test the hypothesis that the OMV plays a central role in compensating cognitive fatigue by translating information on the subjective value of movements and movement goals into corrective control signals for saccades.