Visual field assessment in the “split-brain” patient: effect of the method/laterality of obtaining patient responses on apparent visual field defect size (P1.335)
Bibliographic record
Abstract
OBJECTIVE: To use varying visual field measurement protocols to understand the interhemispheric disconnection syndrome BACKGROUND: Corpus callosotomy is an important tool in the management of certain refractory epilepsies, but may cause an interhemispheric disconnection syndrome. DESIGN/METHODS: A 23 year old right-handed man underwent complete corpus callosotomy for intractable epilepsy. Post-operatively, he had a callosal disconnection (“split-brain”) syndrome, including anomia for objects presented in the left visual field or left hand, left-sided ideomotor apraxia, and “alien limb phenomenon” in the left hand. MRI showed post-surgical changes in the corpus callosum, but no other brain lesions. Visual fields were carefully mapped via several different methods: confrontation finger counting with verbal responses and with saccades, and Goldmann perimetry using the right hand to press the buzzer, using the left hand to press the buzzer, and with saccades to the stimulus light. RESULTS: Some degree of left homonymous hemianopia was found with all methods, but there was a strong dissociation between the size of the visual field defect and the method by which the patient was asked to respond to left visual field stimuli. He appeared to have a complete left homonymous hemianopia when asked to respond verbally or by pressing the buzzer with his right hand, but had only a partial left inferior homonymous quadrantanopia when allowed to respond with saccades or by pressing the buzzer with his left hand. Of all protocols, saccadic responses produced the smallest left visual field defect. Interestingly, the right homonymous hemifield was much less dependent on the method of response. CONCLUSIONS: The extent of a split-brain patient’s visual field defect depends on the method of assessment. By varying the protocol for visual field testing in such a patient, one can expose the intra- and inter-hemispheric connections underlying the normally unified visual experience. Study Supported by:N/A
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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 | 0.001 | 0.003 |
| 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 | 0.001 |
| 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".