图 书 馆
主动推理与不确定性Active Inference and Uncertainty |
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| 课程网址: | http://videolectures.net/uai2011_friston_active/ |
| 主讲教师: | Karl Friston |
| 开课单位: | 伦敦大学 |
| 开课时间: | 2011-08-24 |
| 课程语种: | 英语 |
| 中文简介: |  在本演示中，我将练习动作和感知的自由能公式，特别着重于不确定性的表示形式：自由能原理基于这样的观念，即动作和感知都试图将意外最小化（预测错误）与感觉输入相关联。在此方案中，感知是通过调整内部大脑状态和连接来优化感官预测的过程。同时将动作视为对感觉输入的自适应采样，以确保其符合感知预测（这被称为主动推断）。动作和感知都依赖于不确定性的最佳表示，该不确定性对应于预测误差的精度。在神经生物学上，这可以通过预测误差单位的突触后增益来编码。我希望通过对提示，顺序运动的简单模拟来说明该框架的合理性。至关重要的是，驱动运动的预测基于层次生成模型，该模型可推断运动发生的环境。这意味着我们可以通过更改提示的上下文（顺序）来暂时混淆代理。这些模拟提供了上下文不确定性和集合切换的（贝叶斯最优）模拟，可以根据行为和电生理反应来表征。有趣的是，人们可以破坏精确度（突触后增益）的编码，以产生与帕金森氏病相似的病理行为。我将用它作为一个玩具示例，说明信息理论上的不确定性方法如何帮助理解动作选择和设定切换。 |
| 课程简介: | In this presentation, I will rehearse the free-energy formulation of action and perception, with a special focus on the representation of uncertainty: The free-energy principle is based upon the notion that both action and perception are trying to minimize the surprise (prediction error) associated with sensory input. In this scheme, perception is the process of optimizing sensory predictions by adjusting internal brain states and connections; while action is regarded as an adaptive sampling of sensory input to ensure it conforms to perceptual predictions (this is known as active inference). Both action and perception rest on an optimum representation of uncertainty, which corresponds to the precision of prediction error. Neurobiologically, this may be encoded by the postsynaptic gain of prediction error units. I hope to illustrate the plausibility of this framework using simple simulations of cued, sequential, movements. Crucially, the predictions driving movements are based upon a hierarchical generative model that infers the context in which movements are made. This means that we can temporarily confuse agents by changing the context (order) in which cues are presented. These simulations provide a (Bayes-optimal) simulation of contextual uncertainty and set-switching that can be characterized in terms of behaviour and electrophysiological responses. Interestingly, one can lesion the encoding of precision (postsynaptic gain) to produce pathological behaviours that are reminiscent of those seen in Parkinson's disease. I will use this as a toy example of how information theoretic approaches to uncertainty may help understand action selection and set-switching. |
| 关 键 词: | 贝叶斯; 自由能原理 |
| 课程来源: | 视频讲座网 |
| 数据采集: | 2021-05-08：zyk |
| 最后编审: | 2021-05-08：zyk |
| 阅读次数: | 100 |