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arXiv 2004.11114cs.LGcs.CVq-bio.NCstat.ML
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使用深度神经网络和对抗鲁棒性提高fMRI解码的可解释性

Improving the Interpretability of fMRI Decoding using Deep Neural Networks and Adversarial Robustness

National Institute of Mental Health(国家心理健康研究所)

Patrick McClure, Dustin Moraczewski, Ka Chun Lam, Adam Thomas, Francisco Pereira

摘要:

深度神经网络(DNN)正越来越多地用于根据功能性磁共振成像(fMRI)数据进行预测。然而,它们被广泛认为是不可解释的“黑匣子”,因为很难发现DNN在这个过程中使用了什么输入信息,这在认知神经科学和临床应用中都很重要。显着图是一种常见的方法,用于生成输入特征对预测的相对重要性的可解释的可视化。然而,创建地图的方法通常会失败,因为DNN对输入噪声敏感,或者过于关注输入而对模型关注太少。评估显着性图与真正相关的输入信息的对应程度也具有挑战性,因为地面真相并不总是可用的。在本文中,我们回顾了各种用于生成基于梯度的显着性图的方法,并提出了一种新的对抗性训练方法,我们开发了这种方法来使DNN对输入噪声具有鲁棒性,目的是提高可解释性。我们介绍了两个定量评估程序的显着图方法在功能磁共振成像,适用于每当DNN或线性模型正在训练解码一些信息从成像数据。我们使用已知复杂激活结构的合成数据集,以及针对DNN和人类连接组项目(HCP)数据集中任务解码的线性模型生成的显着图来评估程序。我们的主要发现是,显着性地图与不同的方法产生的解释性差异很大,在合成和HCP功能磁共振成像数据。值得注意的是,即使DNN和线性模型在性能水平相当的情况下进行解码,DNN显着图在可解释性方面的得分也高于线性模型显着图(通过权重或梯度导出)。最后,使用我们的对抗训练方法生成的显着性图优于其他方法。

英文摘要:

Deep neural networks (DNNs) are being increasingly used to make predictions from functional magnetic resonance imaging (fMRI) data. However, they are widely seen as uninterpretable "black boxes", as it can be difficult to discover what input information is used by the DNN in the process, something important in both cognitive neuroscience and clinical applications. A saliency map is a common approach for producing interpretable visualizations of the relative importance of input features for a prediction. However, methods for creating maps often fail due to DNNs being sensitive to input noise, or by focusing too much on the input and too little on the model. It is also challenging to evaluate how well saliency maps correspond to the truly relevant input information, as ground truth is not always available. In this paper, we review a variety of methods for producing gradient-based saliency maps, and present a new adversarial training method we developed to make DNNs robust to input noise, with the goal of improving interpretability. We introduce two quantitative evaluation procedures for saliency map methods in fMRI, applicable whenever a DNN or linear model is being trained to decode some information from imaging data. We evaluate the procedures using a synthetic dataset where the complex activation structure is known, and on saliency maps produced for DNN and linear models for task decoding in the Human Connectome Project (HCP) dataset. Our key finding is that saliency maps produced with different methods vary widely in interpretability, in both in synthetic and HCP fMRI data. Strikingly, even when DNN and linear models decode at comparable levels of performance, DNN saliency maps score higher on interpretability than linear model saliency maps (derived via weights or gradient). Finally, saliency maps produced with our adversarial training method outperform those from other methods.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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