Presynaptic inhibition of pre‐Bötzinger complex neurons in high calcium and disturbed seizure‐like inspiratory bursting in low calcium in newborn rat brainstem slices
Bibliographic record
Abstract
Inspiratory pre‐Bötzinger complex (preBötC) rhythm in brainstem slices in physiological (3mM) K + is depressed by raising superfusate Ca 2+ from 1mM to 1.5mM. Here, we studied cellular mechanisms of such Ca 2+ block of preBötC rhythm and quantified extracellular preBötC interneuron and preBötC‐driven hypoglossal (XII) motoneuron responses to varied Ca 2+ and Mg 2+ . In 400µm thick newborn rat brainstem slices, preBötC/XII rhythm stopped after <2h in 3K + ‐1.2Ca 2+ , but was restored in 7mM K + . Stable preBötC/XII rhythm in 7K + ‐1.2Ca 2+ was blocked by 2‐3mM Ca 2+ without effect on resting potential or input resistance of preBötC and non‐preBötC inspiratory neurons or tonic neurons. preBötC/XII burst rates increased while amplitudes decreased in <1.2Ca 2+ until rhythms stopped in <0.25Ca 2+ . =0.8mM Ca 2+ evoked seizure‐like activity, partially masking inspiratory XII bursts. Lowering Mg 2+ from 1mM to 0.25mM in 7K + ‐1.2Ca 2+ did not affect preBötC/XII rhythms, whereas 3mM Mg 2+ depressed their rate and amplitude to 43% and 82% of control, respectively. Findings show that inspiratory interneuron and XII motoneuron networks in brainstem slices are relatively insensitive to extracellular Mg 2+ , but generate stable rhythm only in 0.8‐1.2mM Ca 2+ . Lack of postsynaptic membrane effects suggests that Ca 2+ block of isolated preBötC networks involves primarily presynaptic mechanisms. Supported by CIHR‐MFN, CIHR, AHFMR.
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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 | 0.001 |
| 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".