A quantitative and morphological study of projection neurons in lamina I of the rat lumbar spinal cord
Bibliographic record
Abstract
In the rat lumbar spinal cord the major supraspinal targets for lamina I projection neurons are the caudal ventrolateral medulla (CVLM), lateral parabrachial area (LPb) and periaqueductal grey matter (PAG). In this study we have estimated the number of lamina I neurons retrogradely labelled from each of these sites in the L4 segment, as well as the proportion that can be labelled by injecting different tracers into two separate sites. Our results suggest that this segment contains approximately 400 lamina I projection neurons on each side, and that approximately 85% of these can be labelled from either the CVLM or the LPb on the contralateral side. Around 120 lamina I cells in L4 project to the PAG, and over 90% of these cells can also be labelled from the CVLM or LPb. Most lamina I neurons projecting to CVLM or LPb are located in the contralateral dorsal horn, but in each case some cells were found to have bilateral projections. We also examined horizontal sections to investigate morphology and the expression of the neurokinin 1 (NK1) receptor in cells labelled from CVLM, LPb or PAG. There were no consistent morphological differences between these groups, however, while cells with strong or moderate NK1 receptor-immunostaining were labelled from LPb or CVLM, they seldom projected to the PAG. These results suggest that many lamina I cells project to more than one site in the brain and that those projecting to PAG may represent a distinct subclass of lamina I projection neuron.
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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 | 0.001 | 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".