Post-activation depression produces extensor H-reflex suppression following flexor afferent conditioning
Bibliographic record
Abstract
Abstract Suppression of the extensor H-reflex by flexor afferent conditioning is thought to be produced by a long-lasting inhibition of extensor Ia-afferent terminals via primary afferent depolarization (PAD) activated by GABA A receptors. Considering the recent finding that PAD does not produce presynaptic inhibition of Ia-afferent terminals, we examined if H-reflex suppression is instead mediated by post-activation depression of the test extensor Ia-afferents triggered by PAD-evoked spikes and/or by a long-lasting inhibition of the extensor motoneurons. A brief conditioning vibration of the flexor tendon suppressed both the extensor soleus H-reflex and the tonic discharge of soleus motor units for 300 ms, indicating that part of the H-reflex suppression was mediated by a long-lasting inhibition of the extensor motoneurons. When activating the flexor afferents electrically to produce conditioning, the soleus H-reflex was also suppressed for 300 ms, but only when a short-latency reflex was evoked in the soleus muscle by the conditioning input itself. In mice, a similar short-latency reflex was evoked when optogenetic or afferent activation of GABAergic (GAD2 + ) neurons produced PAD large enough to evoke orthodromic spikes in the test Ia-afferents, causing post-activation depression of subsequent monosynaptic excitatory-post-synaptic potentials. The time course of this post-activation depression and related H-reflex suppression (lasting 2 s) was like rate-dependent depression that is also due to post-activation depression. We conclude that extensor H-reflex inhibition by brief flexor afferent conditioning is produced by both post-activation depression of extensor Ia-afferents and long-lasting inhibition of extensor motoneurons, rather than from PAD directly inhibiting Ia afferent terminals.
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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) | 0.001 | 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".