Multiple timescales in the adaptation of the rotational VOR
Multiple timescales in the adaptation of the rotational VOR
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DOI：
10.1152/jn.00688.2014
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发表时间：
2015-05-01
影响因子：
2.5
通讯作者：
Ramat, Stefano
中科院分区：
文献类型：
--
作者：
Colagiorgio, Paolo;Bertolini, Giovanni;Ramat, Stefano
尽管产生这些动作的神经肌肉系统不同，但指向目标的动作，如指指方向和扫视动作，已被证明具有相似的神经结构。这种结构包括一个被控制的致动器的逆模型，它产生支配肌肉的命令，以及一个致动器的正向模型，它预测这些命令的感官后果，并允许在线运动纠正。最近的研究表明，目标导向的运动也有类似的基于多个时间尺度的运动学习和运动记忆机制。旋转前庭-眼反射（rVOR）也可能基于类似的结构，这一假说最近被提出。我们假设多重时间尺度是大脑对可塑性-稳定性困境的解决方案，允许在保持稳定的运动控制能力的同时适应暂时和突然的变化。如果是这样的话，那么我们也会期望反射运动的适应遵循同样的原则。因此，我们研究了8名健康受试者的rVOR增益适应，使用自定义范式，旨在调查自发恢复的存在，我们认为这是运动学习中多时间尺度的标志。我们的实验结果表明，8名受试者中有6人出现了自发恢复。因此，我们建立了一个基于两种隐藏状态过程的rVOR适应数学模型，该模型适应了眼运动植物的小脑前向模型，并表明它准确地模拟了rVOR增益适应的实验数据，而单一时间尺度学习过程无法做到这一点。
Goal-directed movements, such as pointing and saccades, have been shown to share similar neural architectures, in spite of the different neuromuscular systems producing them. Such structure involve an inverse model of the actuator being controlled, which produces the commands innervating the muscles, and a forward model of the actuator, which predicts the sensory consequences of such commands and allows online movement corrections. Recent studies have shown that goal-directed movements also share similar motor-learning and motor-memory mechanisms, which are based on multiple timescales. The hypothesis that also the rotational vestibulo-ocular reflex (rVOR) may be based on a similar architecture has been presented recently. We hypothesize that multiple timescales are the brain's solution to the plasticity-stability dilemma, allowing adaptation to temporary and sudden changes while keeping stable motor-control abilities. If that were the case, then we would also expect the adaptation of reflex movements to follow the same principles. Thus we studied rVOR gain adaptation in eight healthy human subjects using a custom paradigm aimed at investigating the existence of spontaneous recovery, which we considered as the hallmark of multiple timescales in motor learning. Our experimental results show that spontaneous recovery occurred in six of eight subjects. Thus we developed a mathematical model of rVOR adaptation based on two hidden-states processes, which adapts the cerebellar-forward model of the ocular motor plant, and show that it accurately simulates our experimental data on rVOR gain adaptation, whereas a single timescale learning process fails to do so.