Special role of parietal cortex in binocular rivalry demonstrated by fMRI comparison with stimulus rivalry
Bibliographic record
Abstract
Binocular rivalry results in perceptual alternations with conflicting images in each eye. Stimulus rivalry allows a similar percept despite repeated swapping of the images in each eye (Logothetis et al, 1996, Blake, 2001). Recent studies have further characterized the parameters required for rivalry, and proposed an integrated framework that may suggest a similar mechanism for both types of rivalry (Van Boxtel et al, 2008). However, a direct comparison of binocular and stimulus rivalry with fMRI has not been reported. We tested subjects with matched stimuli in both rivalry conditions. The stimuli were 1.4 cpd sinusoidal gratings (left & right oblique orientations) at 3.8 deg. Luminance contrast was 100%. For binocular rivalry, dynamic images were presented dichoptically (with polarizers) for 90msec periods with a periodic short blank ISI of 60 msec. For stimulus rivalry, the stimuli were identical except that the images shown to each eye were swapped at 6.67 Hz. We employed active scans where subjects indicated alternations with key press, as well as scans with passive viewing only. Overall, cortical activation for binocular rivalry was consistently greater than for stimulus rivalry. In whole brain statistical maps, this was pronounced in the intraparietal sulcus. Follow-up analysis with retinotopic regions of interest showed also that binocular rivalry exceeded stimulus rivalry in V1, V2, V3, and V3A. Based on comparisons between active and passive conditions, we interpret parietal activity to reflect a relatively automatic process that is triggered by object individuation/attentional tracking. In contrast, regions of ventral temporal cortex might reflect active categorization demands. These results suggest that despite a global network similar to binocular rivalry, the increased interocular masking in stimulus rivalry results in lower BOLD signals as early as V1, consistent with a lower effective contrast and slower alternations. These physiological observations are relevant to competing models of rivalry. Meeting abstract presented at VSS 2014
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.002 | 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".