提出随机导联编码方法,提升生物信号自监督学习的通道泛化能力。
A comprehensive evaluation of pretraining strategies for channel-agnostic contrastive self-supervision of biosignals
- 用随机导联子集构造正样本对,替代传统时间增广或邻近片段。
- 在脑电和心电任务中均优于现有方法,脑电任务超越当前最优模型。
- 适合多变导联数的生物信号场景,尤其适用于跨设备数据训练。
对比学习在计算机视觉中表现优异,依赖于正样本对的构建,通常通过数据增强实现。然而,对于多变量时间序列,有效增强设计困难;且生物信号数据集的输入通道数常因应用而异,限制了特定通道配置下预训练大模型的通用性。针对此问题,本文研究面向通道无关自监督的生物信号预训练策略,提出对比随机导联编码(CRLC),即使用输入通道的随机子集构造正样本对,并与基于增强和时间邻近片段的方法进行比较。我们在脑电(EEG)和心电(ECG)数据上进行预训练,再微调至下游任务。实验表明,CRLC在两种场景的通道无关设置下均优于对比方法。尤其在脑电任务中,其性能超越当前最优参考模型;尽管该参考模型在心电任务中仍占优,但引入CRLC后可达到相当水平。结论:CRLC有助于提升通道异构设置下的模型泛化能力。代码已开源:https://github.com/theabrusch/Multiview_TS_SSL。
原文摘要 · Abstract (English)
Contrastive learning yields impressive results for self-supervision in computer vision. The approach relies on the creation of positive pairs, something which is often achieved through augmentations. However, for multivariate time series effective augmentations can be difficult to design. Additionally, the number of input channels for biosignal datasets often varies from application to application, limiting the usefulness of large self-supervised models trained with specific channel configurations. Motivated by these challenges, we set out to investigate strategies for creation of positive pairs for channel-agnostic self-supervision of biosignals. We introduce contrastive random lead coding (CRLC), where random subsets of the input channels are used to create positive pairs and compare with using augmentations and neighboring segments in time as positive pairs. We validate our approach by pre-training models on EEG and ECG data, and then fine-tuning them for downstream tasks. CRLC outperforms competing strategies in both scenarios in the channel-agnostic setting. Notably, for EEG tasks CRLC surpasses the current state-of-the-art reference model. While, the state-of-the-art reference model is superior in the ECG task, incorporating CRLC allows us to obtain comparable results. In conclusion, CRLC helps generalization across variable channel setups when training our channel-agnostic model. The code is available at https://github.com/theabrusch/Multiview_TS_SSL.
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