An optimized framework for simultaneous EEG–fMRI at 7T enabling safe, high-quality human brain imaging with millisecond temporal resolution and sub-millimeter spatial resolution
Sainz Martinez et al., Imaging Neuroscience, 2025

Central scientific question
This study addresses a clear and strategic question for contemporary neuroscience: is it possible to perform simultaneous EEG–fMRI at 7 Tesla with sufficient safety, signal quality, and functional sensitivity for real human (basic and clinical) applications?
In other words, can the extreme spatial resolution gains of 7T fMRI coexist with the temporal precision of EEG without one modality compromising the other?

An optimized framework for simultaneous EEG–fMRI at 7T enabling safe, high-quality human brain imaging with millisecond temporal resolution and sub-millimeter spatial resolution

The experiment
The authors develop and validate a complete technological framework for EEG–fMRI at 7T, integrating three key advances:

1. Compact EEG configurations with shortened cabling to reduce induced artifacts.

2. Reference sensors, enabling active correction of gradient, pulse, and motion artifacts.

3. An adapted transmission chain, compatible with high-density RF receive coils required for sub-millimeter fMRI.

Two EEG systems are compared—one laboratory-adapted prototype and one industrial solution (BrainCap MR7Flex)—and evaluated in healthy participants for thermal safety, EEG signal quality, MRI quality, and functional sensitivity (resting state and eyes-open/eyes-closed paradigms).

Why this experiment answers the question
The design is particularly robust because it:

• compares with-EEG vs without-EEG acquisitions in the same subjects, isolating the true impact of EEG hardware on fMRI;

• tests demanding protocols (sub-millimeter fMRI, SMS, real functional analyses);

• evaluates not only SNR, but functionally meaningful metrics (resting-state networks, fALFF, connectivity, ICA, alpha–BOLD modulation).

This allows the authors to conclude not just that it “works,” but under which conditions and limits it works.

Main results (objective synthesis)

• Safety: no evidence of excessive heating or SAR violations in GE-EPI protocols, even at high spatial resolution.

• MRI: moderate SNR reductions (~15–25%), mainly related to B1 perturbations, but no detectable loss of functional sensitivity in resting-state analyses.

• EEG: although raw artifacts are severe, post-correction signals preserve canonical EEG signatures, including resting alpha rhythms, microstates, and eyes-open/eyes-closed modulation.

• EEG–fMRI integration: robust correlations between alpha power and occipital BOLD confirm functionally meaningful neurovascular coupling, even at 7T.

The MR7Flex system consistently outperforms the laboratory prototype, indicating a level of technological maturity suitable for broader dissemination.

BrainLatam reading — Body, APUS, and temporality
From a BrainLatam perspective, this work is critical because it reunites time and space in the living human brain. EEG preserves bodily–temporal dynamics (rhythms, transitions, states), while 7T fMRI reveals the fine-grained spatial architecture in which these dynamics unfold.
This opens the door to studying APUS (extended proprioception) and embodied network dynamics at scales that were previously inaccessible—such as cortical layers, propagation trajectories, and regimes of neural stability and destabilization.

Limits and next steps
The authors appropriately note that:

• sequences with higher RF load (SE-EPI, MP2RAGE, ASL, VASO) require additional caution;

• task-based and laminar analyses still demand dedicated validation;

• further improvements are expected through parallel transmit (pTx) and new electrode materials.

These limits do not weaken the study; rather, they precisely define the next necessary experiments.

Final synthesis
This work establishes a methodological milestone: EEG–fMRI at 7T moves from a niche demonstration to a viable platform for advanced human neuroscience.
It is not merely about improving images, but about enabling new scientific questions, where milliseconds and sub-millimeters coexist to investigate consciousness, epilepsy, resting-state networks, interoception, and fine-grained cortical dynamics.

In BrainLatam terms:

when the method respects the body, the body speaks again — in the right time and in the right territory.

Ref.: 

Martinez, C. S., Wirsich, J., Jäger, C., Warbrick, T., Vulliémoz, S., Lemay, M., Bastiaansen, J., Wiest, R., & Jorge, J. (2025). An optimized framework for simultaneous EEG-fMRI at 7T enabling safe, high-quality human brain imaging with millisecond temporal resolution and sub-millimeter spatial resolution. Imaging Neuroscience. https://doi.org/10.1162/imag.a.983