Identifying Neural Source Dynamics from Unknown Local Interventions
Organizations: Mohamed bin Zayed University of Artificial Intelligence (MBZUAI), Abu Dhabi, UAE · Carnegie Mellon University (CMU), Pittsburgh, PA, USA
Abstract
Electroencephalography (EEG) records mixtures of brain-source activity. Even with a known anatomical forward model, experiments that excite only part of the source-state space leave the dynamics unidentified, and repetition cannot resolve the ambiguity. We show that unknown local mechanism changes can supply the missing information. We consider linear dynamics among fixed anatomical sources with known source-state initialization patterns. Changing one source's update rule for one transition leaves a rank-one, source-specific signature in subsequent EEG: subtracting matched baseline responses isolates it, and the forward model identifies the source and calibrates its response history. Combining these histories with initialization responses recovers source interactions without baseline reachability and without first identifying the intervention coefficients. We establish sufficient recovery conditions, a direct estimator, and a noise-sensitivity bound conditional on correct source labels. Simulated EEG on anatomy derived from magnetic resonance imaging confirms the information gain: with baseline excitation confined to four of twelve source coordinates, eight unknown changes recover all dynamics in 32/32 systems, whereas baseline realization, baseline regression through an invertible forward model, and changes that leave the tested states unexposed all fail, and explicitly constructed alternative dynamics reproduce every baseline mean. Where baseline information suffices, direct reconstruction is also more reliable than a matched-information spectral estimator. Nonlocal changes and forward-model error limit accuracy even when source labels are correct.
Figures & tables
| Direct, all eight modes exposed | |||||
|---|---|---|---|---|---|
| Sensor/process SD | Success | med. | med. | p90 | |
| 0.01/0.002 | 4,608 | 24/32 | 6.33 | 8.08 | 11.85 |
| 0.01/0.002 | 18,432 | 32/32 | 3.24 | 3.97 | 6.02 |
| 0.01/0.002 | 73,728 | 32/32 | 1.66 | 1.99 | 3.04 |
| 0.04/0.008 | 4,608 | 0/32 | 26.50 | 29.52 | 40.88 |
| 0.04/0.008 | 18,432 | 3/32 | 12.79 | 15.34 | 22.50 |
| Joint success | p90 (%) | |||
|---|---|---|---|---|
| Intervention law | Direct | Spectral-local | Direct | Spectral-local |
| Row suppression (primary) | 155/160 | 141/160 | 4.28 | 9.20 |
| General row change (control) | 157/160 | 139/160 | 4.16 | 9.99 |
Appendix figures & tables16 assets
Supplementary material from the paper’s appendix.
Appendix
| Symbol | Dimension | Meaning |
|---|---|---|
| Source state, sensor observation, controlled input | ||
| Positive integers | Output-history and insertion-time horizons | |
| Nonnegative integers | Output lag ; insertion time ; absolute episode time | |
| Baseline transition matrix | ||
| Leadfield and initialization map | ||
| One-transition change to receiving row |
| Method | Valid | Success | Median | Median | p90 |
|---|---|---|---|---|---|
| Direct | 160 | 155 | 2.925 | 2.203 | 4.279 |
| Spectral-local | 153 | 141 | 3.252 | 2.361 | 9.204 |
| Target-oracle direct | 160 | 155 | 2.925 | 2.203 | 4.279 |
| Calibrated full- commutator | 160 | 124 | 3.771 | 3.116 | 15.754 |
| Diagonal-only approximation | 160 | 0 | 250.988 | 47.935 | 54.743 |
| Success | Valid | Median | p90 | |||
|---|---|---|---|---|---|---|
| 12/8 | 256 | 98,304 | 63/57 | 73/69 | 2.69/3.48 | 32.85/ |
| 24/16 | 64 | 98,304 | 42/14 | 80/73 | 7.35/13.08 | 12.60/34.16 |
| 48/32 | 16 | 98,304 | 0/0 | 77/0 | 26.02/ | 38.02/ |
| 24/16 | 256 | 393,216 | 77/65 | 80/80 | 3.62/5.33 | 6.42/10.77 |
| 48/32 | 256 | 1,572,864 | 60/19 | 80/75 | 6.32/8.94 | 10.80/39.60 |
| Sensor/process SD | Success | (%) | (%) | ||||
|---|---|---|---|---|---|---|---|
| med. | p90 | med. | p90 | ||||
| 0.01/0.002 | 12 | 4,608 | 24/32 | 6.33 | 10.29 | 8.08 | 11.85 |
| 0.01/0.002 | 48 | 18,432 | 32/32 | 3.24 | 5.24 | 3.97 | 6.02 |
| 0.01/0.002 | 192 | 73,728 | 32/32 | 1.66 | 2.64 | 1.99 | 3.04 |
| 0.04/0.008 | 12 | 4,608 | 0/32 | 26.50 | 37.15 | 29.52 | 40.88 |
| 0.04/0.008 | 48 | 18,432 | 3/32 | 12.79 | 19.70 | 15.34 | 22.50 |
| Condition | Coverage rank | Gate | Finite direct | Finite gated | Success |
|---|---|---|---|---|---|
| All exposed | 12 | 32/32 | 32/32 | 32/32 | Table 6 |
| One unexposed | 11 | 3/32 | 1/32 | 1/32 | 0/32 |
| All unexposed | 4 | 0/32 | 0/32 | 0/32 | 0/32 |
| Partial reachability | Full reachability | |||||
|---|---|---|---|---|---|---|
| Method | Success | Success | ||||
| Direct | 1.62 | 1.78 | 32/32 | 2.45 | 3.06 | 32/32 |
| Inverse + contrasts, OLS | 18.69 | 74.40 | 0/32 | 23.34 | 92.29 | 0/32 |
| Inverse + contrasts, GCV | 18.63 | 75.40 | 0/32 | 23.43 | 95.94 | 0/32 |
| Baseline half, OLS | 704.53 | 363.71 | 0/32 | 27.10 | 42.62 | 3/32 |
| Baseline half, GCV | 81.91 | 195.09 | 0/32 | 24.06 | 31.74 | 3/32 |
| Partial reachability | Full reachability | |||||
|---|---|---|---|---|---|---|
| Condition | Success | Success | ||||
| , lower noise | 3.27 | 3.90 | 31/32 | 5.14 | 6.68 | 30/32 |
| , lower noise | 1.62 | 1.78 | 32/32 | 2.45 | 3.06 | 32/32 |
| , lower noise | 1.22 | 1.33 | 32/32 | 2.03 | 2.22 | 32/32 |
| 4,608, higher noise | 13.22 | 14.42 | 2/32 | 21.03 | 24.05 | 0/32 |
| 18,432, higher noise | 6.56 | 7.16 | 28/32 | 9.82 | 12.48 | 9/32 |
| Modes | Recovered | Maximum | |||
|---|---|---|---|---|---|
| 6 | 1 | 5 | 9 | 0/32 | |
| 6 | 2 | 6 | 12 | 32/32 | |
| 6 | 4 | 8 | 12 | 32/32 | |
| 6 | 8 | 12 | 12 | 32/32 | |
| 12 | 1 | 5 | 12 | 31/32 | |
| 12 | 2 | 6 | 12 | 32/32 |
| Noise | Episodes | Direct | Standalone EM | Direct + EM |
|---|---|---|---|---|
| Lower | 18,432 | 2.99%; 8/8 | 53.78%; 0/8 | 2.95%; 8/8 |
| Lower | 73,728 | 1.57%; 8/8 | 53.66%; 0/8 | 1.57%; 8/8 |
| Higher | 18,432 | 12.19%; 1/8 | 46.22%; 0/8 | 11.96%; 1/8 |
| Higher | 73,728 | 6.40%; 5/8 | 47.62%; 0/8 | 6.36%; 6/8 |
| Design | Valid | Success | Median | Median | p90 | |
|---|---|---|---|---|---|---|
| 24,576 | Positive-only | 0 | 0 | |||
| 24,576 | slope | 155 | 77 | 10.371 | 8.265 | 22.731 |
| 24,576 | slope | 158 | 120 | 5.165 | 4.144 | 10.695 |
| 98,304 | Positive-only | 0 | 0 | |||
| 98,304 | slope | 158 | 120 | 5.165 | 4.144 | 10.695 |
| 98,304 | slope | 160 | 150 | 2.553 | 2.062 | 5.401 |
| Row class | Estimator, targets | Valid | Success | Median | p90 |
|---|---|---|---|---|---|
| Exact gains | Hybrid, 4 | 160/160 | 144/160 | 1.965 | 6.704 |
| Exact gains | Direct, 8 | 160/160 | 142/160 | 2.383 | 7.016 |
| Arbitrary rows | Hybrid, 4 | 160/160 | 0/160 | 310.997 | 1267.994 |
| Arbitrary rows | Direct, 8 | 160/160 | 157/160 | 2.106 | 4.157 |
| Arbitrary rows | Spectral-local, 8 | 153/160 | 139/160 | 2.915 | 9.989 |
| Participant | Site | Current (mA) | Trials | Transfer rank 1 | Target | Other site |
|---|---|---|---|---|---|---|
| 01 | K13–14 | 1/5 | 38/36 | .974 | .977 | .293 |
| 01 | N2–3 | 1/5 | 38/36 | .894 | .966 | .200 |
| 01 | S1–2 | 1/5 | 27/34 | .949 | .953 | .242 |
| 01 | S5–6 | 1/5 | 38/32 | .974 | .976 | .125 |
| 03 | R ′ 2–3 | .3/.5 | 35/42 | .893 | .896 | .179 |
| 05 | G ′ 8–9 | .1/.3 | 44/43 | .978 | .980 | .556 |
| Median error (mm) | Error p90 (mm) | Held-out angle | Peak agreement | |
|---|---|---|---|---|
| 1 | 13.68 | 33.24 | 66.88% | |
| 2 | 13.68 | 24.79 | 75.63% | |
| 4 | 13.68 | 24.28 | 83.13% | |
| 8 | 13.68 | 24.28 | 89.69% | |
| 16 | 13.68 | 24.28 | 92.50% |
| Skull conductivity (S/m) | Correct labels | Recovery | (%) | (%) |
|---|---|---|---|---|
| 0.0030 | 100% | 0/16 | 26.63 | 34.66 |
| 0.0045 | 100% | 0/16 | 11.17 | 15.26 |
| 0.0060 (nominal) | 100% | 16/16 | ||
| 0.0090 | 100% | 0/16 | 15.99 | 23.38 |
| 0.0120 | 100% | 0/16 | 27.52 | 40.05 |
| Nominal readout | True readout | |||||
|---|---|---|---|---|---|---|
| (S/m) | Recovery | (%) | (%) | Recovery | (%) | (%) |
| 0.0030 | 0/16 | 27.13 | 34.70 | 13/16 | 4.47 | 3.15 |
| 0.0045 | 0/16 | 12.61 | 15.76 | 13/16 | 3.64 | 2.45 |
| 0.0060 | 13/16 | 3.25 | 2.11 | 13/16 | 3.25 | 2.11 |
| 0.0090 | 0/16 | 16.61 | 23.27 | 14/16 | 2.92 | 1.79 |
| 0.0120 | 0/16 | 27.41 | 39.76 | 14/16 | 2.77 | 1.64 |