Unexpected cone position in 6‐hydroxydopamine‐treated dark‐adapted goldfish retina
Bibliographic record
Abstract
Dopamine (DA) is an important modulator of light‐adaptation in the vertebrate retina. A known source of DA in the retina is amacrine or interplexiform cells, but another potential source is the retinal pigmented epithelium (RPE). The neurotoxin 6‐hydroxydopamine (6‐OHDA) has been used extensively to ablate DAergic retinal neurons and could be used to distinguish between neuronal and RPE sources of DA. We have, therefore, examined first the impact of 6‐OHDA on light‐induced cone contraction, a phenomenon mediated by D2 DA receptors. Under MS‐222 anesthesia, adult goldfish ( C. auratus ) received two 50 μg intraocular injections of 6‐OHDA on consecutive days. After 10 days, control (uninjected) or 6‐OHDA‐treated fish were placed in the light (>100 lux) or in complete darkness for 1 hr and then sacrificed, eyes removed and fixed in glutaraldehyde. Retinas were then isolated, cones labeled with anti‐zrp1 (ZIRC, Eugene, OR) and cone length determined from confocal z‐stack reconstruction. In control light‐adapted retinas, cones were contracted, with a length of 55 ± 3 µm (mean ± SD), compared to cones from dark‐adapted retinas (115 ± 7 µm). In light‐adapted retinas, treated with 6‐OHDA, cones were contracted (55 ± 1 µm) but in dark‐adapted 6‐OHDA‐treated retinas cones were partially contracted (82 ± 5 µm). A previous study reported similar results and suggested that the partially contracted cone position in dark‐adapted 6‐OHDA‐treated retina indicated a role for DA in dark‐adaptation. Another possibility is that DAergic neurons damaged, but not destroyed by 6‐OHDA, have increased tonic DA release. To investigate this further, we are currently determining to what extent cone position in 6‐OHDA‐treated retinas is affected by treatment with D2 DA receptor agonists and antagonists. Funded by the NSERC.
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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 | 0.000 | 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 | 0.001 |
| 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".