Crossed apraxia without aphasia in a left hander with a right hemisphere stroke
Bibliographic record
Abstract
Limb is a disorder of skilled movement characterized by the inability to use tools and pantomime or imitate gestures. Apraxia most often results from left hemisphere lesions and is frequently accompanied by aphasia. Here we present the case of an 82 year old, left-handed man seen one month after an ischemic stroke affecting the right frontal lobe and basal ganglia. Assessment revealed a marked limb apraxia, including impairments to pantomime, imitation, and conceptual praxis tasks. Language testing revealed a minor anomic aphasia with relatively preserved speech production and comprehension, but a marked agraphia and alexia. The patient also demonstrated difficulty with working memory and constructing drawings of common objects from memory. We argue that this is a case of apraxia in which lateralization for praxis control, typically involving the left hemisphere, is controlled by the right hemisphere. Despite crossed praxis, this patient's preserved verbal comprehension and speech implies these functions are controlled by the intact left hemisphere. The deficits observed on conceptual praxis tasks suggest that unlike verbal comprehension action comprehension like praxis is subserved by the right hemisphere. Although relatively rare, other cases of crossed-apraxia have been reported in the literature, and provide insight into the potential dissociation among the neural representations underlying praxis, language, reading and writing.Acknowledgments: Funded by Heart and Stroke Foundation of Ontario (EAR and SEB)
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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) | 0.001 | 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 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".