Diffuse distribution of sulforhodamine-labeled neurons during serotonin-evoked locomotion in the neonatal rat thoracolumbar spinal cord
Bibliographic record
Abstract
The fluorescent dye sulforhodamine-101 undergoes synaptic activity-dependent endocytotic uptake and consequent retrograde transport in presynaptic neurons. We used sulforhodamine to identify thoracolumbar spinal premotor neurons (T11-L6) activated during serotonin (5-HT) -induced hindlimb locomotor-like activity in the in vitro neonatal rat spinal cord preparation. Sulforhodamine labeling required locomotor-like activity because few neurons were labeled unless bath applied 5-HT recruited the locomotor rhythm. In contrast, N-methyl-D-aspartate (NMDA; 5 microM) profoundly increased spinal neuronal labeling irrespective of locomotor activity. The contribution of false-positive activity labeling during locomotion induced by application of NMDA with 5-HT (Kjaerulff et al. [1994] J Physiol (Lond). 478:265-273) necessitated the present re-mapping of sulforhodamine-labeled neurons. During 5-HT-evoked locomotion, the sulforhodamine-labeled neurons were diffusely scattered within the spinal cord with predominant labeling in lamina VII. Motor nuclei (lamina IX) and superficial laminae (I-II) were typically devoid of labeled cells in the isolated spinal cord. However, unilateral labeling of motoneurons was achieved when the ipsilateral hindlimb remained attached, suggesting that uptake in motoneurons requires an intact neuromuscular junction. The rostrocaudal incidence and distribution of labeled neurons was uniform in spinal segments L1-L5, with reduced numbers observed in thoracic and L6 spinal segments. Mean total cell labeling was less than 400 per spinal segment, suggesting recruitment from a very small fraction of the neurons contained within the spinal cord (calculated at < 0.1%). These results are consistent with the limited transfer of locomotor-related synaptic activity (Raastad et al. [1996] Neuron 17:729-738) and severe synaptic fatigue (Lev-Tov and Pinco [1992] J Physiol. 447:149-169; Pinco and Lev-Tov [1993] J Neurophysiol. 70:1151-1158; Fleoter and Lev-Tov [1993] J Neurophysiol. 70:2241-2250) observed in the neonatal rat spinal cord.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".