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arXiv 2510.09415q-bio.NCcs.CLcs.LGcs.NE

使用自然主义MEG-fMRI编码模型以高空间和时间分辨率估计大脑活动

Estimating Brain Activity with High Spatial and Temporal Resolution using a Naturalistic MEG-fMRI Encoding Model

Carnegie Mellon University(卡内基梅隆大学)

Beige Jerry Jin, Leila Wehbe

AI总结:

本研究提出一种基于Transformer的MEG-fMRI编码模型,融合自然主义数据,以高时空分辨率估计皮层源活动,优于单模态模型和经典方法,并验证了跨受试者与模态的泛化能力。

摘要:

当前的非侵入性神经成像技术在空间分辨率与时间分辨率之间进行权衡。虽然脑磁图(MEG)能够捕捉快速的神经动力学,而功能磁共振成像(fMRI)能够对大脑活动进行空间定位,但现有的源定位或MEG-fMRI融合方法在同时保持两种高分辨率方面仍是一个未解决的挑战,尤其是对于单次试验的自然主义数据。我们在受试者被动聆听超过七小时的叙事故事时采集了全脑MEG,使用了与一个开放fMRI数据集(LeBel等人,2023年)中相同的刺激。我们开发了一种基于Transformer的编码模型,结合了来自这两个自然主义语音理解实验的MEG和fMRI数据,以高时空分辨率估计潜在的皮层源响应。我们的模型被训练为同时从多个受试者预测MEG和fMRI,其中包含一个表示我们估计的重建皮层源的潜在层。我们的模型在预测MEG方面优于常见的单模态编码模型标准,并且在模拟实验中,其源估计在空间和时间保真度上也优于经典的最小范数解。我们通过显示估计的潜在源在未见过的受试者和模态上具有很强的泛化能力来验证它们。在我们的源空间中估计的活动在一个全新的数据集中比一个在ECoG上训练的编码模型更好地预测了皮层脑电图(ECoG)。通过整合大型自然主义实验、MEG、fMRI和编码模型的力量,我们提出了一条实现毫秒级和毫米级大脑映射的实用途径。

英文摘要:

Current non-invasive neuroimaging techniques trade off between spatial resolution and temporal resolution. While magnetoencephalography (MEG) can capture rapid neural dynamics and functional magnetic resonance imaging (fMRI) can spatially localize brain activity, a unified picture that preserves both high resolutions remains an unsolved challenge with existing source localization or MEG-fMRI fusion methods, especially for single-trial naturalistic data. We collected whole-head MEG when subjects listened passively to more than seven hours of narrative stories, using the same stimuli in an open fMRI dataset (LeBel et al., 2023). We developed a transformer-based encoding model that combines the MEG and fMRI from these two naturalistic speech comprehension experiments to estimate latent cortical source responses with high spatiotemporal resolution. Our model is trained to predict MEG and fMRI from multiple subjects simultaneously, with a latent layer that represents our estimates of reconstructed cortical sources. Our model predicts MEG better than the common standard of single-modality encoding models, and it also yields source estimates with higher spatial and temporal fidelity than classic minimum-norm solutions in simulation experiments. We validated the estimated latent sources by showing its strong generalizability across unseen subjects and modalities. Estimated activity in our source space predict electrocorticography (ECoG) better than an ECoG-trained encoding model in an entirely new dataset. By integrating the power of large naturalistic experiments, MEG, fMRI, and encoding models, we propose a practical route towards millisecond-and-millimeter brain mapping.

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