Abnormal Visual System Connectivity in Human Albinism
Bibliographic record
Abstract
Introduction Albinism is an inherited condition caused by mutations in genes involved in melanin synthesis. The lack of melanin results in ophthalmic deficits such as reduced visual acuity and misrouting at the optic chiasm (OC). Structural MRI has revealed narrower OCs and smaller lateral geniculate nucleus (LGN) (McKetton et al., 2014). The number of LGN relay neurons has been linked to LGN volume, suggesting a correlation between LGN size and the number of tracts traveling through the optic radiation (OR) to the primary visual cortex (V1) (Yucel et al., 2000). Using diffusion data and both deterministic and probabilistic tractography, we studied differences in the primary visual pathway between albinism and controls. The medial geniculate nucleus (MGN), an auditory nucleus adjacent to the LGN, was investigated to observe potential compensatory alteration in morphology and connectivity. Methods Patients and controls were scanned using a Siemens Trio 3T MRI scanner and 32-channel head coil. LGN regions of interest (ROIs) were created from multiple registered and averaged proton density weighted images. A T1-weighted 3D-MPRAGE sequence with 1 mm3 isotropic voxel size was used to generate high-resolution images for V1 segmentation. Diffusion tensor imaging (DTI) scans were acquired with 64 diffusion directions. Both deterministic and probabilistic tracking methods were run and compared, with LGN as the seed mask and V1 as the target mask in diffusion space. Mean fractional anisotropy and diffusivity maps of visual structures were compared in both groups. Results Our results reveal areas of significantly reduced white matter integrity within visual structures including the OC and OR in patients with albinism compared to controls. We also observe reduced MGN volumes in albinism compared to controls. Conclusions We have demonstrated altered structural development in visual pathways and possible sensory cross-modal interactions using structural and diffusion MRI. Meeting abstract presented at VSS 2016
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.006 | 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".