Electrical synapses interconnecting axons in the optic nerve head–a novel model of optic nerve function
Bibliographic record
Abstract
Abstract Purpose Axons in the optic nerve are arranged in bundles and conducting action potential with resistance related to their membrane. Here, we aim to characterize the function of newly identified gap junctions coupling optic nerve axons with each other’s. Methods Proximal and distal rat optic nerve stumps were processed for immunostainings, electron microscopy (EM), RT‐PCR and western blots (WB). Additional 20 animals were deeply anesthetized, and stainless‐steel screw electrodes were drilled in skulls in standard locations to record fVEPs. Recordings were performed in untouched animals, after retrobulbar injection of saline (negative control) or meclofenamic acid solution (gap junctions’ blocker). Human paraffin cross‐sections of eyeballs for immunostainings were obtained from the Human Eye Biobank for Research, University of Toronto, Canada. Results Immunostaining of rat and human samples revealed presence of Cx45 and 36 in axonal membranes, colocalizing with β3‐tubulin, but not with GFAP. In WB, Cx36 content in optic nerve was approximately halved when compared with retina (0.58 ± 0.005 ‐ proximal stump; 0.44 ± 0.02 ‐ distal stump), Cx45 showed higher levels (0.68 ± 0.0003 ‐ proximal stump; 0.9 ± 0.07 ‐ distal stump). Additionally, we detected transcript of Cx45 and Cx36 in RT‐PCR analysis of optic nerve homogenates. In immunogold‐EM of optic nerve sections, we found electric synapses (formed mostly by Cx45) that are directly coupling neighboring axons. In fVEPs, blocking of gap junctions’ with meclofenamic acid resulted in prolongation of the latency of P1 wave up to 140% after 5 min from retrobulbar injection of this blocker (p < 0.001) and 170% after 30 min (p < 0.001). Conclusions Optic nerve axons do not form absolutely independent conductive channels. They are directly coupled by gap junctions formed in majority by neuronal Cx45. Coupling of axons allows to reduce axonal membrane resistance and accelerates transduction of visual signal.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".