Measurement-Gated Provenance Attenuation for Frozen EEG Representations
Organizations: Mohamed bin Zayed University of Artificial Intelligence (MBZUAI)
Abstract
Frozen EEG representations retain acquisition signatures as well as neural activity. Source predictability alone does not identify what should be removed: it can reflect measurement effects or genuine biological and population differences, which should not be erased. We propose Measurement-Gated Provenance Attenuation (MGPA), built on one principle: measurement evidence determines where correction may act, and preserved information determines what it should aim for. Paired measurement contrasts define a gate outside which nothing changes; inside it, the source score is moved to the value the preserved coordinates already predict: for a fixed affine score, this keeps the same information as any target set by those coordinates and needs the least expected squared movement. Closed-form and critic-guided iterative constructions apply it without source identity or encoder retraining. Three studies test the principle at increasing distance from its assumptions. Under controlled reference changes, where the source-task association is known, MGPA brings source to near chance with task performance unchanged, whereas erasing what predicts source (LEACE) lowers frozen-task AUROC from .753 to .656 while barely touching source; ablations attribute the attenuation to the gate's directions and 2.7x less movement to the conditional target. Across recordings from different devices and electrodes, iterative correction lowers source accessibility while preserving or improving task performance. Finally, one iterative map selected on one task and reused unchanged on existing heads for two others raises their worst-association AUROC (lowest over device-label shifts) by .057 and .019 over LEACE, at a cost to those heads while the training association holds. A reusable correction shows its value in how an existing predictor behaves once acquisition cues stop being reliable, not only in what a probe can read.
Figures & tables
| Interface | Method | Source | Frozen | Refitted | Movement |
|---|---|---|---|---|---|
| Source-blind correction | Identity | 0.683 | 0.753 | 0.753 | 0.000 |
| LEACE | 0.660 | 0.656 | 0.665 | 0.120 | |
| MGPA-CF | 0.510 | 0.753 | 0.753 | 0.028 | |
| Source-aware alignment | CORAL ref. 0 | 0.502 | 0.753 | 0.753 | 0.012 |
| CORAL ref. 1 | 0.502 | 0.753 | 0.753 | 0.012 | |
| FEATMAP ref. 0 | 0.502 | 0.753 | 0.753 | 0.012 |
| A. Temporal N170 | B. Recorded SSVEP | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Interface | Method | ||||||||
| Source-blind correction | Identity | 0.989 | 0.728 | 0.728 | 0.000 | 0.916 | 0.688 | 0.688 | 0.000 |
| LEACE | 0.980 | 0.728 | 0.727 | 0.234 | 0.918 | 0.689 | 0.689 | 0.102 | |
| MGPA-CF | 0.982 | 0.727 | 0.728 | 0.237 | 0.895 | 0.689 | 0.690 | 0.056 | |
| MGPA-Iter | 0.946 | 0.735 | 0.746 | 0.347 | 0.872 | 0.688 | 0.689 | 0.149 | |
| Linear-only ablation | 0.987 | 0.725 | 0.729 | 0.345 | 0.872 | 0.689 | 0.689 | 0.069 | |
| Worst-association AUROC | Control-head AUROC | ||||||
| Interface | Method | P300 | N170 | MMN | P300 | N170 | MMN |
| Source-blind correction | Identity | 0.355 | 0.122 | 0.446 | 0.627 | 0.622 | 0.640 |
| LEACE | 0.601 | 0.384 | 0.614 | 0.622 | 0.621 | 0.639 | |
| MGPA-CF | 0.599 | 0.420 | 0.642 | 0.627 | 0.621 | 0.642 | |
| MGPA-Iter | 0.599 | 0.441 | 0.632 | 0.627 | 0.621 | 0.641 | |
| Source-aware alignment | CORAL | 0.550 | 0.277 | 0.624 | 0.627 | 0.622 | 0.641 |
Appendix figures & tables9 assets
Supplementary material from the paper’s appendix.
Appendix
| Study | Coordinates, calibration and gate | Participants and operating point |
|---|---|---|
| Controlled SSVEP | Pooled EEGPT512; full same-trial CAR/Oz contrasts; 90% directional energy, ranks | Four role rotations; 81 distinct EVAL participants. Native correction/target; VAL budget for permission. |
| Temporal N170 | 240 temporal features; simultaneous Neuroscan/Flex pairs; 90% energy, rank 56 | ; native maps and matched-budget IGBP comparison. |
| Recorded SSVEP | Mean512 correction, readouts; six virtual FIT-local contrasts; 99% energy, rank 328 | ; native maps. |
| P300-selected reuse | EEGPT/PCA256, P300 FIT reference coordinates; 400 simultaneous CAL pairs, rank 8 | ; P300 DEV-selected map, unchanged on N170/MMN. |
| Component | Setting |
|---|---|
| Iterative fits / horizon | Seeds 17, 29, 43; at most 48 stages |
| Source critics | Balanced logistic ( ); GELU MLP, hidden width 128 |
| Conditional-mean anchor | Ridge with intercept and penalty 10 (both constructions) |
| Neural-critic optimizer | AdamW, batch 256, weight decay |
| Gradient stabilizer / damping | / |
| Controlled and real-representation fits | 12 critic epochs, LR , radius |
| Input | Readers and training |
|---|---|
| Common representation | Ordinary and covariance-whitened logistic ( , whitening shrinkage ); GELU MLP with width 128, AdamW, LR , batch 256, weight decay . |
| Direct full tokens | Raw logistic ( ), HEAD-standardized logistic ( ); flat GELU with common training; token network with LayerNorm, shared GELU, concatenation and binary output, LR , batch 128, weight decay , gradient clipping 5. |
| Centered token residuals | Standardized logistic and the same token network with its three restarts/checkpoints. |
| Target | ||||
|---|---|---|---|---|
| Conditional mean | 0.5105 | 0.7496 | 0.7527 | 0.1500 |
| Unconditional mean (FIT) | 0.5214 | 0.7488 | 0.7574 | 0.4063 |
| Zero score | 0.5199 | 0.7479 | 0.7562 | 0.4172 |
| A. Native source accessibility | ||
|---|---|---|
| Correction | ||
| Identity | 0.763 | 0.989 |
| MGPA-Iter | 0.794 | 0.946 |
| Linear-only | 0.663 | 0.987 |
| VAL budget | Method | ||||
|---|---|---|---|---|---|
| .10 | MGPA-Iter | 0.9850 | 0.7274 | 0.7300 | 0.0974 |
| .10 | IGBP | 0.9893 | 0.7292 | 0.7284 | 0.0898 |
| .25 | MGPA-Iter | 0.9643 | 0.7292 | 0.7394 | 0.2422 |
| .25 | IGBP | 0.9877 | 0.7210 | 0.7237 | 0.2239 |
| P300 | N170 | MMN | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Method | A | I | R | A | I | R | A | I | R |
| Identity | 0.770 | 0.568 | 0.355 | 0.914 | 0.547 | 0.122 | 0.753 | 0.603 | 0.446 |
| LEACE | 0.604 | 0.602 | 0.601 | 0.782 | 0.590 | 0.384 | 0.614 | 0.633 | 0.652 |
| MGPA-CF | 0.643 | 0.621 | 0.599 | 0.735 | 0.579 | 0.420 | 0.642 | 0.644 | 0.646 |
| MGPA-Iter | 0.636 | 0.617 | 0.599 | 0.744 | 0.594 | 0.441 | 0.632 | 0.639 | 0.646 |
| CORAL | 0.662 | 0.607 | 0.550 | 0.818 | 0.564 | 0.277 | 0.639 | 0.632 | 0.624 |
| Task | Method | Reference | worst [95% CI] | control head [95% CI] |
|---|---|---|---|---|
| P300 | MGPA-CF | Identity | ||
| P300 | MGPA-CF | LEACE | ||
| P300 | MGPA-Iter | Identity | ||
| P300 | MGPA-Iter | LEACE | ||
| N170 | MGPA-CF | Identity | ||
| N170 | MGPA-CF | LEACE |
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