NeuroAtlas
Project

NeuroAtlas: Benchmarking Foundation Models for Clinical EEG and Brain-Computer Interfaces

arXiv preprint 2605.14698

Konstantinos Kontras1,2,*, Trui Osselaer1,*, Stylianos G. Mouslech1,*, Angeliki-Ilektra Karaiskou1,*, Guido Gagliardi1,*, Thomas Strypsteen1,*, Mohammad Hossein Badiei1, Anku Rani2, Maarten Vanmarcke1, Miguel Bhagubai1, Chanakya Ekbote2, Jaedong Hwang2, Christos Chatzichristos1, Paul Pu Liang2, Maarten De Vos1

1 KU Leuven, 2 MIT, * Equal contribution

Correspondence: konstantinos.kontras@kuleuven.be

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NeuroAtlas overview: four EEG domains, 42 datasets, 260k hours, three model families.
NeuroAtlas overview. NeuroAtlas spans four EEG domains (epilepsy, sleep, brain age, BCI), 42 datasets and ~260k hours of EEG, and benchmarks three model families on each. Total EEG hours per domain: epilepsy 58k h; sleep 201k h (shared with brain age); BCI 170 h. Each domain is evaluated with both standard and clinically grounded tasks: seizure detection with event-level decision metrics (epilepsy); sleep staging, hypnogram-derived features, event detection, and OSA diagnosis (sleep); chronological age estimation and the brain-age gap as a marker of cognitive impairment (brain age); and motor imagery, ERP, SSVEP, and non-neural confound analysis (BCI). Three model families are compared under a unified frozen-encoder probe: 10 EEG foundation models, 3 time-series foundation models, and 7 task-specific supervised baselines.[PDF]

Abstract

Foundation models (FMs) promise to extract unified representations that generalize across downstream tasks. They have emerged across fields including electroencephalography (EEG), but it is less clear how effective they are in this particular field. Published evaluations differ in datasets, in the EEG-specific preprocessing that might influence reported results, and in the reported metrics frequently obscuring the clinical relevance in EEG. We introduce NeuroAtlas, the largest EEG benchmark to date: 42 datasets and ~260k hours covering clinical EEG (epilepsy, sleep medicine, brain age estimation) and brain-computer interfaces, and include multiple datasets per task along with bespoke clinical evaluation metrics. Besides evaluating EEG-FMs with respect to supervised baselines, we present results from generic time-series FMs. We report three findings. First, EEG-specific FMs do not consistently outperform time-series FMs which have neither EEG-focused architectures nor been pretrained on EEG. Second, standard machine learning metrics are insufficient to assess clinical utility: Thus, we thoroughly evaluate more appropriate measures such as the quality of event-level decision-making, hypnogram-derived features, and the brain-age gap in the domains of epilepsy, sleep and brain age respectively. Third, model rankings and performance can vary substantially within domains. We conclude that pretrained models perform largely on par, with only narrow advantages for a few, and that current FMs do not yet deliver on the promise of an out-of-the-box unified EEG model. NeuroAtlas exposes this gap and provides the datasets and metrics for the next generation of unified EEG-FMs.

Main findings

  1. EEG-FMs show no consistent advantage under linear probing

    EEG-FMs performed similarly to supervised models and generic time-series foundation models (TS-FMs). The TS-FMs used neither EEG-specific architectures nor EEG data in pretraining.

  2. Model rankings depend on the evaluation metric

    Model rankings based on a single metric differed from those based on other clinically grounded metrics. Higher scores on standard metrics did not necessarily correspond to better performance on clinically relevant measures.

  3. Performance and rankings vary across datasets

    Both absolute performance and model rankings varied substantially across datasets within the same domain. Evaluation across multiple cohorts is therefore needed to assess how consistently a model performs.

Epilepsy

Seizure detection across seven EEG datasets.

~1,410 participants, ~58,000 hours of EEG

Across the seven cohorts with continuous labels, no model or model family consistently came out on top. Most models performed within one fold standard deviation of the randomly initialized reference. Only NeuroLM and REVE placed in the top three more often than expected by chance.

Epilepsy results: family-best Event-Sens@FA AUC across seven datasets, plus a per-model heatmap.
No model or family is consistently best across datasets, and most models perform on par with random initialization. (a) Family-best Event-Sens@FA AUC across seven continuously-labeled datasets (labels include total EEG hours), as the area under the mean (5-fold) sensitivity vs. log10(FA/h) curve over 0.1–100 FA/h under any-overlap event scoring. The leading EEG-FM differs across datasets and no family consistently dominates. (b) Per-(model, dataset) AUC for 23 models: EEG-FMs, Supervised-Pre, TS-FMs, CBraMod random-init. Cells show mean AUC (bold) and 5-fold std; black borders mark the dataset-best model; red dots flag pretraining/evaluation overlap. Gray bars: per-model means across datasets (top, red dashed: random-init baseline at 0.44) and per-dataset means across models (right). Most per-model means lie within ≈0.05 AUC of the 0.44 baseline; only NeuroLM and REVE exceed it at approx. 1 std (both 0.55), and the dataset-best alternates between NeuroLM, REVE, and SleepFM.[PDF]

Sleep

Sleep staging, hypnogram characterization, sleep-event detection, and obstructive sleep apnea assessment across 15 datasets.

~15,800 participants, ~201,000 hours of EEG

Sleep-staging performance varied substantially across datasets. Without inter-epoch temporal context, EEG-FMs, TS-FMs, and supervised models performed similarly. Moreover, high agreement on individual epochs did not necessarily translate into accurate recovery of the hypnogram features used in clinical practice.

Sleep results: Cohen's kappa, REM-latency MAE, microarousal AUPRC and OSA diagnosis AUROC per model category.
Performance is strongly dataset-dependent across tasks. Metrics are shown for the best-performing model per category, i.e., EEG-FMs, TS-FMs, and Supervised-Pre models with and without temporal context (sequence length ℓ=1), and a random-initialized reference. (a) Cohen's κ sleep staging agreement with ground-truth labels; model categories achieve similar performance when excluding the effects of sequence modeling. (b) MAE between ground truth and predicted REM latency; performance on sleep staging agreement does not always correspond to performance on hypnogram features. (c) AUPRC for microarousal detection, for events with a minimal duration of 3 seconds; the chance baseline is indicated by prevalence. While all model categories perform above baseline, FMs do not reach Supervised-Pre performance. (d) AUROC for diagnosis of OSA compared to healthy patients, and in a cohort with other disorders; chance baseline at 0.5. While OSA is detected in a healthy cohort, performance degrades in the presence of other disorders.[PDF]

Brain Age

Age estimation and brain-age gap analysis across 10 sleep EEG cohorts.

~15,000 participants, ~193,000 hours of EEG

Task-specific supervised models predicted chronological age more accurately than foundation models. However, brain-age gap estimates showed near-chance discrimination between participants with cognitive impairment and age-matched healthy controls across all models evaluated.

Brain age results: Pearson r radar across cohorts, best average ranking per category, and top-10 brain-age-gap AUROC.
Supervised models outperform EEG-FMs for brain age prediction, but performance does not translate to a neurodegenerative assessment biomarker. (a) Radar plot of performance (Pearson's r) of the best model per category across cohorts; supervised brain-age prediction outperforms the rest. (b) Best average ranking of the best model of each category for MAE and r. (c) Top-10 AUROC for cognitive-impairment separation using the brain-age gap (predicted minus chronological age); AUROC measures whether cognitively impaired subjects have a higher gap than age-matched healthy subjects. Although several models show weak positive separation, performance remains modest across model categories, indicating that accurate age prediction does not necessarily yield a robust BAG-based biomarker.[PDF]

BCI

Motor imagery, ERP, SSVEP, and cognitive paradigms across 17 datasets, evaluated using leave-one-subject-out validation.

509 participants, ~170 hours of EEG

Once non-neural confounds are filtered out, motor-imagery performance often drops below significance, while no single foundation model consistently generalizes across BCI paradigms and subjects.

BCI results: normalized balanced accuracy with and without confound filtering, plus a per-dataset heatmap.
MI performance is strongly driven by confounds. Linear probing performance of frozen EEG and time-series foundation models across 17 BCI datasets spanning four paradigms (MI, ERP, SSVEP, Cognitive) for token flattening. Metrics are reported as normalized balanced accuracy (%), where 50% equals chance regardless of the number of classes. The per-dataset significance threshold (p < 0.05, binomial test) is shown as a dashed red line or orange markers. (a) Normalized balanced accuracy on Motor Imagery datasets comparing embeddings extracted without confound filtering and with confound filtering bars for 8 EEG-FMs, 3 TS-FMs and EEGNet supervised model. Error bars denote the standard error of the mean across MI datasets (Wilcoxon signed-rank test; * p < .05, ** p < .01, *** p < .001). Confound filtering significantly affect performance, suggesting that the evaluated models rely primarily on artifacts. (b) Per-dataset heatmap for 8 EEG-FMs and 3 TS-FM evaluated on confound filtered data. Cell color encodes normalized balanced accuracy (40–100%; darker = higher); each cell reports the LOSO average score (bold for dataset-best). Orange stars mark results significantly above chance. Note that due to the varying number of classes and the low sample counts, the significance level is much higher than chance level and varies across datasets.[PDF]

BibTeX

@misc{kontras2026neuroatlas,
      title={NeuroAtlas: Benchmarking Foundation Models for Clinical EEG and Brain-Computer Interfaces},
      author={Konstantinos Kontras and Trui Osselaer and Stylianos G. Mouslech and
              Angeliki-Ilektra Karaiskou and Guido Gagliardi and Thomas Strypsteen and
              Mohammad Hossein Badiei and Anku Rani and Maarten Vanmarcke and
              Miguel Bhagubai and Chanakya Ekbote and Jaedong Hwang and
              Christos Chatzichristos and Paul Pu Liang and Maarten De Vos},
      year={2026},
      eprint={2605.14698},
      archivePrefix={arXiv},
      primaryClass={cs.LG},
      url={https://arxiv.org/abs/2605.14698},
}
BIOMED, KU LeuvenKU LeuvenMIT

Acknowledgements

This work was supported by the Flemish Government under the METHUSALEM programme (METH/26/003, "Methusalem-BioMedAI: Explainable and generative AI for accelerating biomedical discoveries: from genome to function") and by the Flemish Government AI Research Program; several of the authors are affiliated with Leuven.AI of KU Leuven Institute for AI, B-3000 Leuven, Belgium. This work was also supported by the European Union's Horizon Europe research and innovation programme under the Marie Skłodowska-Curie Actions Doctoral Network InSilicoHealth (Grant Agreement No. 101169278). Further support was provided by KU Leuven through project C3/25/059 ("A Multicenter RCT on the impact of Wearable EEG and AI-Based Seizure Detection in absence seizure management"), and by the Research Foundation - Flanders (FWO) through research projects G046925N ("Task- and device-agnostic Artificial Intelligence (AI) for EEG analysis"), and G0C9623N ("Artificial Intelligence (AI) for data-driven personalised medicine"), as well as FWO PhD fellowships 1166926N, 1107725N, 1S30225N, 1S12523N, 1SB5922N, 1S61822N and 1SH4Z24N. The collaboration was also supported by the MIT-Belgium-KU Leuven Seed Fund. The resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation - Flanders (FWO) and the Flemish Government. We acknowledge LUMI-BE for awarding this project access to the LUMI supercomputer, owned by the EuroHPC Joint Undertaking, hosted by CSC (Finland) and the LUMI consortium through a LUMI-BE Regular Access call. LUMI-BE is joint effort from BELSPO (federal), SPW Économie, Emploi, Recherche (Wallonia), Department of Economy, Science & Innovation (Flanders) and Innoviris (Brussels).