MENDR: Manifold Explainable Neural Data Representations

TL;DR

MENDR introduces an interpretable, efficient EEG foundation model using a Riemannian manifold transformer that leverages wavelet features, achieving high performance and transparency for clinical applications.

Contribution

The paper presents MENDR, a novel filter bank-based EEG model with a Riemannian manifold transformer architecture, enhancing interpretability and efficiency over existing models.

Findings

Achieves near state-of-the-art performance on clinical EEG tasks.

Provides geometric visualization of EEG embeddings as ellipsoids.

Uses fewer parameters than comparable models.

Abstract

Foundation models for electroencephalography (EEG) signals have recently demonstrated success in learning generalized representations of EEGs, outperforming specialized models in various downstream tasks. However, many of these models lack transparency in their pretraining dynamics and offer limited insight into how well EEG information is preserved within their embeddings. For successful clinical integration, EEG foundation models must ensure transparency in pretraining, downstream fine-tuning, and the interpretability of learned representations. Current approaches primarily operate in the temporal domain, overlooking advancements in digital signal processing that enable the extraction of deterministic and traceable features, such as wavelet-based representations. We propose MENDR (Manifold Explainable Neural Data Representations), a filter bank-based EEG foundation model built on a novel Riemannian Manifold Transformer architecture to resolve these issues. MENDR learns symmetric positive definite matrix embeddings of EEG signals and is pretrained on a large corpus comprising over 4,000 hours of EEG data, decomposed via discrete wavelet packet transforms into multi-resolution coefficients. MENDR significantly enhances interpretability by visualizing symmetric positive definite embeddings as geometric ellipsoids and supports accurate reconstruction of EEG signals from learned embeddings. Evaluations across multiple clinical EEG tasks demonstrate that MENDR achieves near state-of-the-art performance with substantially fewer parameters, underscoring its potential for efficient, interpretable, and clinically applicable EEG analysis.