Inhibitory control of active expiration by the Kölliker‐Fuse in rats
Bibliographic record
Abstract
Breathing is critically dependent on synchronized activity generated by neural respiratory centres within the pons and medulla. When respiratory drive is elevated, active expiration (AE) is observed, typically expressed by abdominal muscle activity at the end of the expiratory phase (late‐E). It is currently unknown what role the dorsolateral pons, specifically the Kolliker‐Fuse (KF), plays in generating the AE breathing pattern. Using the decerebrated in situ working heart‐brainstem preparation of juvenile male Holtzman rats (60–70 g), motor output from the vagus, phrenic and abdominal nerves were recorded during baseline conditions. The preparations were then exposed to hypercapnic conditions (8% CO2) to recruit AE. Hypercapnia resulted in a significant increase in the amplitude of abdominal late‐E activity (Δ: 118±30%, P<0.05), with little change to the other recorded parameters. During hypercapnia, the pharmacological inhibition of the KF, with bilateral microinjections of (50–75 nL) isoguvacine (10 mM), caused a significant decrease in breathing frequency (Δ: −5±2 cpm, P<0.05) due to increased inspiratory time (0.86±0.1 vs 1.37±0.1 s, P<0.05). Interestingly, while there was no change to the overall expiratory time, the duration (1.86±0.21 vs 1.47±0.13 s, P<0.05) and amplitude (3.6±0.4 vs 0.7±0.2 μV, P<0.05) of post inspiratory (post‐I) vagal activity decreased while the onset of the abdominal late‐E bursts occurred significantly earlier (1.3±0.1 vs 2.4±0.2 s, P<0.05). No changes were observed in the abdominal late‐E burst amplitude after KF inhibition. These findings suggest that the KF plays a relevant inhibitory role in coordinating the transition between post‐I activity and AE during hypercapnia. Support or Funding Information Financial support: NSERC, FAPESP (2013/17251‐6) and NIH/NCCIH (1R01AT008632‐01).
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".