脑电图基础模型对长程时间相关性视而不见：其跨群体脆弱性背后的频谱-时间解离
Cross-Cohort Spectral-Temporal Dissociation in Frozen EEG Foundation-Model Representations
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中文总结 AI 辅助
研究探讨脑电图基础模型对长程时间相关性的表征及跨群体转移情况。通过探测五种模型，发现它们均未按时间顺序表示LRTC，频谱输入模型能恢复1/f但非DFA，跨群体转移方面各模型表现不一，揭示了模型在这方面的局限性。
中文摘要 AI 辅助
**目标**：脑电图（EEG）基础模型（FMs）经训练用于重建或对比对齐短片段，然后汇总成固定嵌入。我们测试了这些嵌入是否保留了由α波段包络的去趋势波动分析（DFA）指数量化的长程时间相关性（LRTC），以及它是否控制跨群体转移。**方法**：我们在两个分布外队列上探测了五种EEG FMs，涵盖原始波形和频谱输入架构（REVE、LaBraM、BENDR、CBraMod、BIOT），将DFA指数的恢复与静态1/f非周期斜率进行比较。通过保序和残差控制来测试汇总或非周期阴影。一个蒙太奇协调的零样本转移任务在三个队列（添加一个西方参考）中比较了冻结嵌入与DFA指数。**主要结果**：五个FMs中没有一个按时间顺序表示LRTC。原始波形模型（REVE、LaBraM、BENDR）既没有恢复DFA指数也没有恢复1/f斜率（R^2 <= 0.12）；对于这三个模型，探测无信息，所以解离特定于频谱输入模型（CBraMod、BIOT），它们强烈恢复了1/f（R^2 = 0.59 - 0.73）但未跨队列恢复DFA。一个经典DFA特征恢复了指数（R^2 = 0.32 - 0.38，可靠性上限为0.64），并且LRTC与非周期斜率正交（r = -0.06）。在跨群体转移方面，冻结的REVE嵌入未超过随机水平（W到K，0.45），无量纲DFA指数定向转移但未达到家族水平显著性；其他四个未统一复制。所有五个都由记录部位轴主导（可解码率为0.98 - 1.00，而随机概率为0.500），而它们丢弃的DFA指数对部位具有鲁棒性（0.71）。
英文摘要
Objective. We tested whether frozen representations from five EEG foundation models support decoding of long-range temporal correlations, measured as the detrended-fluctuation-analysis (DFA) exponent of the alpha-band amplitude envelope. Approach. REVE, LaBraM, BENDR, CBraMod, and BIOT were evaluated in CAUEEG and BrainLat. A common 240 s estimator used 8-13 Hz filtering, DFA over 2-23.8 s, artifact masking, and quality control. One fixed nested-cross-validation readout predicted DFA and a fixed-mode aperiodic exponent. Controls tested pre-pool order sensitivity and aperiodic residualization. Results. CAUEEG included 764 recordings and BrainLat 79. BIOT decoded DFA in CAUEEG (R-squared = 0.232; conditional subject-bootstrap 95 percent interval, 0.121-0.310), and CBraMod was positive but imprecise (R-squared = 0.121; 0.003-0.214). Neither replicated in BrainLat, where all five point estimates were negative. In contrast, CBraMod and BIOT decoded the aperiodic exponent in both cohorts (R-squared = 0.459-0.757). BIOT remained positive after removal of the measured linear aperiodic association in matched CAUEEG data (R-squared = 0.240). The post-hoc order control was batch- and configuration-sensitive. Because chronological EEG epochs are not exchangeable, it was descriptive, not an LRTC-specific test. No revised DFA transfer direction passed source-label permutation testing. Cohort membership was near-ceiling decodable from all five embeddings, but this is not a pure site effect. Significance. CBraMod and BIOT show a replicated, model-specific spectral-temporal dissociation: aperiodic decoding is present in both cohorts, whereas alpha-envelope DFA decoding is cohort-dependent. These findings bound the evaluated readouts; they do not establish representational absence or an architectural cause. Transfer and clinical associations remain exploratory.
发表机构
- Université Laval（拉瓦尔大学）
- NeuroGenis Inc.（NeuroGenis公司）
机构由 AI 辅助整理，请以论文原文为准。
