Effects of daily spontaneous running on the electrophysiological properties of hindlimb motoneurones in rats
Bibliographic record
Abstract
No evidence currently exists that motoneurone adaptations in electrophysiological properties can result from changes in the chronic level of neuromuscular activity. We examined, in anaesthetized (ketamine/xylazine) rats, the properties of motoneurones with axons in the tibial nerve, from rats performing daily spontaneous running exercise for 12 weeks in exercise wheels ('runners') and from rats confined to plastic cages ('controls'). Motoneurones innervating the hindlimb via the tibial nerve were impaled with sharp glass microelectrodes, and the properties of resting membrane potential, spike threshold, rheobase, input resistance, and the amplitude and time-course of the afterhyperpolarization (AHP) were measured. AHP half-decay time was used to separate motoneurones into 'fast' (AHP half-decay time < 20 ms) and 'slow' (AHP half-decay time >/= 20 ms), the proportions of which were not significantly different between controls (58 % fast) and runners (65 % fast). Two-way ANOVA and ANCOVA revealed differences between motoneurones of runners and controls which were confined to the 'slow' motoneurones. Specifically, runners had slow motoneurones with more negative resting membrane potentials and spike thresholds, larger rheobasic spike amplitudes, and larger amplitude AHPs compared to slow motoneurones of controls. These adaptations were not evident in comparing fast motoneurones from runners and controls. This is the first demonstration that physiological modifications in neuromuscular activity can influence basic motoneurone biophysical properties. The results suggest that adaptations occur in the density, localization, and/or modulation of ionic membrane channels that control these properties. These changes might help offset the depolarization of spike threshold that occurs during rhythmic firing.
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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".