The Sagittally Sectioned Rat Hindbrain Preparation: Improved Access to the Brainstem Respiratory Network
Bibliographic record
Abstract
Neurons that control breathing are distributed along the ventral respiratory column (VRC) in the ventrolateral brain stem, extending from the pons to the spinomedullary junction. These networks can be isolated in the en bloc brainstem-spinal cord preparation, which remains spontaneously active for hours under physiological conditions, but which only permits blind single-unit recordings from respiratory network constituents. The transverse slice preparation isolates the minimal neural substrate sufficient for respiratory rhythmogenesis, but does not permit the study of neuronal signaling along the column. Here, the sagittally sectioned rat hindbrain preparation is described. This preparation exposes the VRC transected along its long axis, at its surface, permitting optical recording of network activity using membrane-permeant Ca 2+ indicators, as well as single-unit recording under visual control using differential interference contrast microscopy to patch onto cells identified using Ca 2+ indicators. Because the VRC does not run parallel with the midline or the dorsal brainstem surface, exposing respiratory networks at the preparation’s surface requires that the sagittal surface be cut at the appropriate ventrodorsal (18.6°, relative to the dorsal surface) and rostrocaudal tilt (8.5°, relative to the midline), and mediolateral level. These empirically derived parameters conform with anatomical features of the brainstem: the rostrocaudal tilt aligns with the nucleus ambiguus; the ventrodorsal tilt lies parallel with reticular nuclei striations; the mediolateral level of section abuts a branch of the basilar artery. Detailed methods for isolating the SSRH, stabilizing it in the recording chamber, and recording respiratory networks using a membrane-permeant Ca 2+ indicator are provided here.
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.009 | 0.003 |
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".