A hierarchical system for learning and control

即使是最简单的动作也会被大脑内的多个系统监测和评估。例如，如果我们试图拿起一杯咖啡，但由于某种原因失败了，我们需要一个神经系统来识别这一点，并产生一个学习信号，用于改变随后的行为。然而，这并不是我们在喝咖啡时可能遇到的唯一类型的错误。我们不知道，运动计划--大脑向运动系统发出的一套指令--可能包含错误。此外，运动计划中的错误可能是由环境的意外变化带来的--想象一杯咖啡平衡不佳，当我们伸手去拿它时，它开始滑落。这些类型的错误--计划中的错误和/或环境中意外变化带来的错误--需要在运动本身内迅速调解，以便我们成功地实现运动目标。最近，我提出了分级错误处理假说，认为大脑中有两个不同的错误处理系统：一个负责评估我们行动的成功或失败，另一个系统负责解决运动中运动计划中的错误。我的研究小组最近进行的一系列研究支持等级假说。综上所述，研究结果表明，大脑额叶-中枢部的学习系统在运动输出的评估中起着关键作用。现有的实验证据也支持分层假说，因为它证明了大脑后部区域的错误系统在解决正在进行的运动中初始运动计划中的错误方面所起的作用。构成这一建议基础的研究试图通过确定错误评估的进一步神经标记并检查它们对行为的影响来进一步发展等级假说。此外，我希望改进支撑等级假说的理论框架。重要的是，拟议的研究将进一步加深我们对学习是如何在神经层面上发生的理解，从而提供科学界和普通民众感兴趣的结果。

Even the simplest of movements are monitored and evaluated by multiple systems within the brain. For instance, if we try to pick up a cup of coffee and fail for some reason, we need a neural system that can identify this and generate a learning signal that would be used to modify subsequent behaviour. However, this is not the only type of error we might encounter while reaching for a cup of coffee. Unbeknownst to us, the motor plan - the set of instructions that the brain issues to the motor system to carry out the movement - may contain errors. Additionally, errors in the motor plan may be brought about by unexpected changes in the environment - imagine the cup of coffee is poorly balanced and that it begins to slip as we reach for it. These types of errors - errors in planning and/or errors brought about by unexpected changes in the environment need to be rapidly mediated within the movement itself in order for us to successfully achieve our movement goal. Recently, I have proposed the hierarchical error processing hypothesis which states that there are two distinct error processing systems in the brain: a system that is responsible for evaluating the success or failure of our actions, and a system that is tasked with resolving errors in the motor plan within the movement. A series of recent studies by my research group supports the hierarchical hypothesis. In sum, the results demonstrate that a learning system within frontal-central parts of the brain plays a key role in the evaluation of motor output. Existing experimental evidence also supports the hierarchical hypothesis as it demonstrates the role of error systems in posterior regions of the brain in the resolution of errors in the initial motor plan within an ongoing movement. The research that forms the basis of this proposal seeks to further develop the hierarchical hypothesis by identifying further neural markers of error evaluation and examining their impact on behaviour. Further, I hope to improve the theoretical framework which underlies the hierarchical hypothesis. Importantly, the proposed research will further our understanding of how learning occurs at the neural level, thus providing results which will be of interest to the scientific community and the general population.