Instructive Signals for Motor Learning

描述（由申请人提供）：运动学习是指通过练习使动作变得流畅和准确的过程。运动学习在儿童早期发展中很重要，并持续到成年，因为控制我们运动的神经回路需要重新校准，以应对大脑或身体因受伤、疾病或正常衰老过程而发生的变化。运动学习依赖于一个叫做小脑的大脑区域，小脑功能障碍患者的动作笨拙、不协调。小脑的两个主要输入之一是来自脑干下橄榄的“攀爬纤维”输入。一个有影响力的小脑功能理论认为，攀爬纤维携带控制运动学习的错误信号。然而，最近的证据表明，运动学习可以在攀爬纤维缺乏指导性信号的情况下发生。因此，在大脑中实现运动学习的方法似乎不止一种。这个项目的目标是确定运动学习的哪些方面是由攀爬纤维的活动控制的，哪些方面的学习依赖于其他神经机制。这个问题将通过研究眼球运动对前庭刺激的反应（即，编码头部运动的感觉信号）及其通过运动学习的调节来解决。大多数（如果不是全部的话）运动都是由前庭信号引导的。眼球运动对前庭刺激的反应称为前庭眼反射（VOR）。这种前庭反射的功能是稳定视网膜上的视觉图像，在身体运动期间保持良好的视力是必不可少的。由VOR驱动的眼动振幅和眼动时间都可以通过小脑依赖学习进行自适应调整，因此VOR可以作为研究控制眼动振幅和眼动时间的神经机制的模型系统。

DESCRIPTION (provided by applicant): Motor learning is the process by which movements become smooth and accurate through practice. Motor learning is important during early childhood development, and continues throughout adulthood, because the neural circuits controlling our movements need to be recalibrated in response to changes in the brain or body due to injury, disease, or the normal aging process. Motor learning depends on a brain region called the cerebellum, and patients with cerebellar dysfunction have clumsy, uncoordinated movements. One of the two main inputs to the cerebellum is the "climbing fiber" input from the inferior olive in the brainstem. An influential theory of cerebellar function suggested that the climbing fibers carry the error signals that control motor learning. However, recent evidence suggests that motor learning can occur in the absence of instructive signals in the climbing fibers. Thus, there seems to be more than one way to implement motor learning in the brain. The goal of this project is to determine which aspects of motor learning are controlled by the activity of the climbing fibers, and which aspects of learning rely on other neural mechanisms. This question will be addressed by studying the eye movement responses to vestibular stimuli (i.e., the sensory signals encoding movements of the head) and their regulation by motor learning. Most, if not all, movements are guided by vestibular signals. The eye movement response to a vestibular stimulus is called the vestibulo-ocular reflex (VOR). This vestibular reflex functions to stabilize visual images on the retina, and is essential for maintaining good vision during movements of the body. Both the amplitude and the timing of the eye movements driven by the VOR can be adaptively modified by cerebellum-dependent learning, and thus the VOR serves as a model system for studying the neural mechanisms controlling movement amplitude and timing more generally. PUBLIC HEALTH RELEVANCE: An important characteristic of neural circuits is their plasticity, their ability to change with experience and to compensate when injury or disease damages the nervous system. This project studies the error signals that guide the changes in a neural circuit during learning. An improved understanding of this process will inform the development of more effective interventions for a broad range of neurological and psychiatric disorders.