The Organization of Central Retinal Projections in Anna's Hummingbirds ( <i>Calypte anna</i> ) and Zebra Finches ( <i>Taeniopygia castanotis</i> )
Bibliographic record
Abstract
Hummingbirds (family Trochilidae) are easily recognized due to their unique ability to hover. Critical to hovering flight is head and body stabilization. In birds, stabilization during flight is mediated, among other things, by the detection of optic flow, the motion that occurs across the entire retina during self-motion. Given this increased requirement for stabilization, it is not surprising that previous studies have shown that hummingbirds have neural specializations in the visual pathways involved in the detection of optic flow. Particularly, previous studies have found some structural and functional differences in the hummingbird brain, in the pretectal nucleus lentiformis mesencephali (LM): compared to other avian species, LM shows a massive hypertrophy, and LM neurons have unique response properties to optic flow stimuli. Here, we used intraocular injections of a neural tracer, cholera toxin subunit B (CTB) conjugated with a fluorescent molecule, to study the retinal projections in Anna's hummingbirds (Calypte anna) and compare them to those of a similarly sized non-hovering species, the zebra finch (Taeniopygia castanotis). Retinal targets in both birds were similar and correspond closely to those reported in other birds from a variety of avian clades. Importantly, we found differences in the projections to LM between hummingbirds and zebra finches. Consistent with previous reports of specialization of LM, it was more intensely labelled compared to other retinal-recipient nuclei in hummingbirds. Moreover, this increase in intensity was most apparent in the lateral subnucleus. This study reinforces previous evidence that the LM of hummingbirds is adapted to sustain the unique flight abilities of this clade.
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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 | 0.000 | 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 | 0.000 |
| 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".