Functional organisation of visual pathways in a patient with no optic chiasm
Bibliographic record
Abstract
Background: Patients with albinism or congenital achiasma offer a unique opportunity to study cerebral reorganization and inter-hemispheric communication in the face of highly anomalous inputs to striate cortex. Objective: We describe neuroimaging studies in a patient with congenital achiasma and seesaw nystagmus, but full visual fields. Methods: The subject underwent structural MRI, DTI studies, and functional MRI with monocular stimulation with light/dark checkerboards, motion, and objects and faces, as well as retinotopic quadrantic stimulation. Results: Structural MRI confirmed the absence of an optic chiasm, which was corroborated by diffusion tensor imaging (DTI). Monocular full-field presentation of chequerboards resulted in activation restricted to the ipsilateral primary visual cortex, providing functional confirmation of a lack of crossing visual inputs to striate cortex. Areas V2 and V3 also showed activation only by the ipsilateral eye. Additional analysis showed no difference between the on and off conditions in the contralateral visual cortex, indicating no sub-threshold activation in V1-V3 and confirming a true lack of response to visual stimulation. Monocular retinotopic stimulation of the left and right visual fields further showed reorganisation within primary visual cortex. Monocular presentation of motion versus static stimuli revealed bilateral activation in the area V5 complex by stimuli presented to either eye, Similarly monocular presentation of faces and objects produced bilateral activation in the posterior and middle fusiform gyrus. Conclusions: These results show the functional reorganisation of striate cortex to anomalous monocular full-field input and indicate that inter-hemispheric integration of information does not occur at early V2/V3 levels, but at an intermediate stage (V5) and higher levels (fusiform gyri). Meeting abstract presented at VSS 2012
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".