用非线性模型分离fMRI中的独立脑功能信号,发现与已知网络一致的活动模式。
Isolating Nonlinear Independent Sources in fMRI with $β$-TCVAE Models

- 基于β-TCVAE框架,通过非线性变换解耦混合的时空脑信号。
- 恢复出具有生物学意义的非线性空间成分,包括默认模式网络等经典网络。
- 适用于追求脑功能网络可解释性的神经影像研究者,尤其关注非线性动态建模。
从非线性功能磁共振成像(fMRI)数据中学习有意义的潜在表示仍是神经影像分析中的核心挑战。传统独立成分分析因依赖线性混合假设,难以捕捉大脑动力学固有的非线性复杂结构。近年来,深度表示学习方法被提出作为替代方案,但多数在模拟数据或自然图像基准上验证,真实神经影像数据上的应用有限。本文采用β-TCVAE(总相关变分自编码器),其为β-VAE的改进版本,无需训练时引入额外超参数。我们将其适配至fMRI数据,用于非线性源解耦,旨在将混合的空间与时间脑信号分离为可解释成分。结果表明,该框架能恢复出具有生物学意义的非线性空间成分,包括默认模式网络等公认的内在连接网络。此外,通过功能网络连通性评估,所学潜在结构展现出一致且可解释的大脑组织模式。本研究为非线性表示学习与fMRI分析的结合提供了初步探索。
原文摘要 · Abstract (English)
Learning meaningful latent representations from nonlinear fMRI data remains a fundamental challenge in neuroimaging analysis. Traditional independent component analysis, widely used due to its ability to estimate interpretable functional brain networks, relies on a linear mixing assumption for latent sources, limiting its ability to capture the inherently nonlinear and complex organization of brain dynamics. More recently, deep representation learning methods have emerged as promising alternatives for modeling nonlinear latent structure. However, many of these approaches have been evaluated primarily on simulated datasets or natural image benchmarks, with comparatively limited validation on real-world neuroimaging data such as fMRI. In this work, we are motivated by the $β$-TCVAE (Total Correlation Variational Autoencoder), a refinement of the $β$-VAE framework for learning latent representations without introducing additional hyperparameters during training. We adapt and modify this model to fMRI data for nonlinear source disentanglement, aiming to separate mixed spatial and temporal brain signals into interpretable components. We show that the $β$-TCVAE framework can recover meaningful nonlinear spatial components with biological relevance, including well-established intrinsic connectivity networks such as the default mode network. Furthermore, we evaluate the learned representations using functional network connectivity, showing that the latent structure captures coherent and interpretable brain organization patterns. This study provides a pilot investigation that bridges nonlinear representation learning and fMRI analysis.
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