Control Theoretic Model of the Cerebellum

小脑的控制理论模型

• 批准号: RGPIN-2019-05728
• 负责人: Broucke, Mireille
• 金额: $ 2.04万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=682191
• 关键词: Control; Theoretic; Model; Cerebellum

My research concerns the development of a control theoretic model of the cerebellum. A complete understanding of the cerebellum is one of the great open problems of neuroscience today, not very different from Kepler's problem on the motion of the planets, in its day. ******The cerebellum has remarkable features. It contains about half the neurons of the brain (more than the cerebral cortex), it has a purely feedforward neural architecture (in contrast with the recurrent architecture of the cerebral cortex), it operates on a timescale of milliseconds, 1-2 orders of magnitude faster than the cerebral cortex. Most importantly, despite the many regulatory functions it performs and independently of the particular function it is regulating (e.g. motor control, locomotion, eye movement, speech timing, emotion regulation), the computations are identical. What are those computations? Since the 1960's, control theory and robotics have offered plausible explanations. Yet no complete model has been found, to date.******I initiated research on modeling the cerebellum during my sabbatical in 2017. I began with an experiment in cognitive psychology on adaptation to visuomotor rotations. A human subject is presented with a task to make a fast reach with the hand to a target disk on a horizontal screen. When the cursor angle is rotated from the hand angle by an amount unknown to the subject, an implicit (subconscious) process of adaptation takes place. This process is believed to reside in the cerebellum. We developed a model that predicts the dynamic phenomena observed in the experiments.******The cerebellum is also involved in eye movement. Behaviours of the oculomotor system include the vestibuloocular reflex, smooth pursuit, saccades, and the optokinetic reflex. The computations (in the cerebellum) are the same for both the visuomotor experiment and the oculomotor system. We developed a second generation model that both recovers the behaviours of the oculomotor system and reveals the computations of the cerebellum.******Rather than deriving a mathematical model based on analysis of experimental data, I approach the cerebellum modeling problem as one of synthesis: to synthesize a control law using tools from control theory. An advantage of applying control theory in this way is that, like Newton's laws that tell us about immutable limits on the motion of bodies in a gravitational field, so too control theory explains the immutable limits of a control system to achieve tracking in the presence of unknown disturbances. In essence, control theory narrows the search for a plausible mathematical model. ******The first phase of our research to develop a control-theoretic model of the cerebellum is well underway. The second phase is to relate the model to the neurophysiology of the cerebellum. We hope our work can contribute to basic science as well as to understanding neurological disorders such as ataxia, Huntington's disease, and Parkinson's disease.**************

我的研究涉及小脑控制理论模型的发展。对小脑的完全理解是当今神经科学的最大开放问题之一，与当时的开普勒在行星运动方面的问题并没有很大不同。 ******小脑具有出色的特征。它包含大脑神经元的一半（比大脑皮层多），它具有纯粹的前馈神经结构（与大脑皮质的复发结构相比），它在毫秒的时间表上运行，比毫秒的时间表比大脑皮质更快。最重要的是，尽管它执行了许多调节功能，并且独立于其调节的特定功能（例如，运动控制，运动，眼动，言语时机，情绪调节），但计算是相同的。这些计算是什么？自1960年代以来，控制理论和机器人技术提供了合理的解释。然而，迄今为止尚未发现完整的模型。向人类受试者提出了一项任务，可以用手快速到达水平屏幕上的目标磁盘。当光标角从手角旋转时，被对象未知的量时，会发生一个隐式（潜意识）的适应过程。据信这个过程位于小脑中。我们开发了一个预测实验中观察到的动态现象的模型。******小脑也参与了眼动。动眼运动系统的行为包括前庭反射，平滑追捕，扫视和光相反射。 Visuomotor实验和动眼系统的计算（在小脑中）相同。我们开发了一个第二代模型，该模型既恢复了动眼系统的行为，又揭示了小脑的计算。******而不是基于实验数据分析的数学模型，而是将小脑建模问题作为合成：使用控制理论的工具合成控制法。以这种方式应用控制理论的一个优点是，就像牛顿的定律告诉我们引力领域中身体运动的不变限制一样，也是如此，控制理论也解释了控制系统的不变限制，以在存在未知干扰的情况下实现跟踪。从本质上讲，控制理论缩小了对合理数学模型的搜索。 ******我们研究的第一阶段是开发小脑控制理论模型的第一阶段。第二阶段是将模型与小脑的神经生理学联系起来。我们希望我们的工作能有助于基础科学，并了解诸如共济失调，亨廷顿氏病和帕金森氏病等神经系统疾病。****************