Mechanisms of theta burst transcranial ultrasound induced plasticity in the human motor cortex
Bibliographic record
Abstract
Background Transcranial ultrasound stimulation (TUS) is a novel non-invasive brain stimulation technique with high depth penetrance and spatial resolution. Theta-burst TUS (tbTUS) is a plasticity-inducing protocol which increases motor cortical excitability for up to 30 min following 80s of sonication. While this protocol may have therapeutic potential for the treatment of psychiatric and neurological disorders, the mechanisms of action of TUS remain unclear. Objective We conducted the first pharmacological study to examine the mechanisms of TUS in human primary motor cortex. By administering brain-active drugs with known mechanisms of action, we aimed to elucidate the mechanisms of tbTUS. Methods Fourteen healthy subjects participated in a within-subjects randomized, double-blind, cross-over study with five visits. At each visit, one of four study drugs (carbamazepine – Na + channel blocker, nimodipine – L-type Ca 2+ channel blocker, lorazepam – positive allosteric modulator of gamma-aminobutyric acid (GABA) type A receptor, dextromethorphan – N-methyl-d-aspartate receptor antagonist) or placebo was administered in random order, followed by tbTUS. Results The plasticity effects of tbTUS on motor cortex excitability measured by motor-evoked potential amplitudes elicited by transcranial magnetic stimulation were reduced by all study drugs compared to placebo. Conclusion: tbTUS may induce NMDA-dependent synaptic plasticity since the effects are blocked by increased GABA A receptor activities and voltage-gated Na + and Ca 2+ channels blockers. These results are consistent with the hypotheses that tbTUS induced long-term potentiation-like mechanisms and that TUS involves activation of mechanosensitive Na + and Ca 2+ channels. Alternatively, non-specific pharmacologically induced changes in excitatory/inhibitory balance might have interfered with the effects of tbTUS.
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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 | 0.000 |
| 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".