Visuo-perceptual abilities in patients with atypical Alzheimer's Disease
Bibliographic record
Abstract
We tested the spatial attention and visuo-perceptual abilities of two patients with atypical Alzheimer's disease. Neuroimaging revealed hypoperfusion in parietal, posterior temporal, and lateral occipital cortex. In patient R.D, who exhibited neglect and extinction, hypoperfusion was lateralized to the right hemisphere. In patient M.M., who had no spatial neglect, hypoperfusion was left lateralized. Both patients were impaired in the copying and matching of simple shapes, but recognition of more complex figures was relatively preserved. A 2-AFC task assessed the patients' ability to perceive two objects at the same time. In this task, two concentric figures (e.g., a circle and a square) were briefly displayed. When the figures were displayed sequentially, patients correctly reported whether the shapes were the same (e.g., two circles), or not (e.g., a circle and a square). In contrast, performance was close to chance when the figures were displayed simulatenously. This simultanagnosia may stem from a deficit in spatial attention. To explore this possibility, in a follow-up study two concentric figures were displayed, and patients had to report the shape of one of them (i.e., the target). In separate blocks, the feature that defined the target was either spatial (e.g., the ‘large’ figure) or non-spatial (e.g., the ‘black’ figure). Spatial cues led to more accurate performance than non-spatial cues. This result is consistent with an attentional account of simultanagnosia, by which patients can attend to a selected stimulus, but have difficulties disengaging from it.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".