Changes in motor cortex excitability with stimulation of anterior thalamus in epilepsy
Bibliographic record
Abstract
BACKGROUND: Deep brain stimulation (DBS) is an effective treatment for movement disorders and pain. Recently, bilateral DBS of the anterior nucleus of thalamus (AN) was performed for the treatment of intractable epilepsy. This surgery reduced seizure frequency in an initial group of patients. However, its physiologic effects on the cortex and mechanisms of action remain poorly understood. Different classes of antiepileptic drugs (AEDs) have distinct effects on the excitatory and inhibitory circuits in the motor cortex, which can be studied noninvasively by transcranial magnetic stimulation (TMS). OBJECTIVE: To examine the effects of bilateral AN DBS on motor cortex excitability in epilepsy and compare these to the known effects of AEDs. METHODS: Cortical excitability was assessed in five medicated epilepsy patients with bilateral stimulators implanted in the anterior thalamus and nine healthy controls. Single and paired TMS were used to examine cortical inhibitory and facilitatory circuits. Electromyography was recorded from the dominant hand, and TMS was applied over the contralateral motor cortex. Patients were studied during DBS turned off (OFF condition), DBS with cycling stimulation mode (1 minute on, 5 minutes off; CYCLE), and DBS with continuous stimulation (CONTINUOUS) in random order on 3 consecutive days. RESULTS: Motor thresholds were increased in the patients regardless of DBS condition. Active short-interval intracortical inhibition (SICI) was significantly reduced in the OFF and CYCLE conditions but returned toward normal levels in the CONTINUOUS condition. Rest SICI, long interval intracortical inhibition, and silent period duration were unchanged. CONCLUSIONS: Increased short-interval intracortical inhibition with continuous deep brain stimulation (DBS) suggests that thalamic DBS might drive cortical inhibitory circuits, similar to antiepileptic drugs that enhance gamma-aminobutyric acid inhibition.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".