Parabrachial area and nucleus raphe magnus inhibition of corneal units in rostral and caudal portions of trigeminal subnucleus caudalis in the rat
Bibliographic record
Abstract
The cornea has been used extensively as a means to selectively stimulate trigeminal nociceptive neurons. The aim of this study was to determine the effects of descending modulatory control pathways on corneal unit activity by comparing the effects of conditioning stimulation of the pontine parabrachial area (PBA CS) and nucleus raphe magnus (NRM CS). Electrical stimulation of the cornea at A- and C-fiber intensities was used to activate neurons in two regions of the trigeminal spinal nucleus, the subnucleus interpolaris/caudalis transition (Vi/Vc, 'rostral units') and laminae I-II at the subnucleus caudalis/cervical cord transition (Vc/C1, 'caudal units'), in chloralose-anesthetized rats. Corneal units were further classified according to convergent cutaneous receptive field properties and PBA projection status. None of 48 rostral and 23/28 caudal units projected to the ipsilateral or contralateral PBA. PBA CS inhibited the cornea-evoked responses (<75% change from control) of approximately 65% of rostral and caudal units regardless of neuronal class. For rostral corneal units, PBA CS inhibited A- and C-fiber input equally (15+/-3 and 18+/-14% of control, respectively), whereas among caudal units, A-fiber input was inhibited more than C-fiber input (26+/-5 and 64+/-12% of control, respectively, P<0.01). The magnitude of NRM CS inhibition on cornea-evoked activity of both rostral and caudal units was not different from that seen after PBA CS. Glutamate microinjections into PBA also inhibited rostral and caudal corneal units (6/9 tested). These results indicate that corneal input to rostral and caudal units is modified by activation of descending controls from the PBA and NRM. The significance for processing corneal sensory information is discussed in terms of functional differences between rostral and caudal neurons.
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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 | 0.000 |
| 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) | 0.000 | 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".