TMS-EEG of FrontSensory Co-activation and Brain State in Suprathreshold Frontal Cortex
Bibliographic record
Abstract
Transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG) can provide an opportunity to study the intact brain by perturbing it and recording its response. It is crucial to have a clear understanding of the level of inherent sensory co-activation in the TMS-EEG signal, and to devise methods to minimize these effects. Additionally, TMS-EEG recordings are performed without considering the state of the brain at the time of stimulation. Investigating the possible modulatory effect of phase and power of EEG oscillation before the TMS pulse on the outcome of TMS-EEG recordings is of interest. We explored the differentiation of the auditory co-activation from TMS response in healthy participants (Study-1). We further studied the topic of sensory co-activation and state-of-the-art methods for masking it (Study-2). Additionally, we investigated the effect of phase and power of EEG oscillations before stimulation on single trial TMS-EEG response (Study-3). We observed a distinctively higher level of cortical reactivity to active TMS compared to the auditory sham and the sham coil. The early response (<80 ms) in the active conditions (state-of-the-art- masking vs conventional) did not show significant differences over the stimulation site and across all of the electrodes (global activity). The late response (<275 ms) over the stimulation site was not significantly different between the active conditions, but the difference was significant in the global activity. Only active paired-pulse protocols in both studies resulted in a significant level of cortical inhibition measured by LICI. No effect of phase was observed on the single trial cortical reactivity while a significant effect for pre-stimulus power was evident in theta and beta bands with higher power resulting in larger single trial cortical reactivity to TMS compared with lower power. While sensory co-activation in suprathreshold TMS-EEG of dorsolateral prefrontal cortex is a concerning factor, it can be masked effectively with appropriate masking procedures, and reliable data regarding cortical reactivity to TMS can be achieved. Though we found no modulation of cortical reactivity to TMS by the phase of EEG oscillations, we did observe that higher power in theta and beta bands prior to stimulation can lead to larger cortical reactivity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".