The large-scale organization of object processing in the ventral and dorsal pathways
Bibliographic record
Abstract
One of the hallmark properties of the ventral visual pathway is sensitivity to object shape. Accumulating evidence, however, suggests that object-based representations are also derived by the dorsal visual pathway although less is known about the characteristics of these representations, their spatial distribution, and their perceptual importance. To bridge this gap, the present study combined psychophysical and fMRI experiments in which participants viewed and recognized objects with different levels of scrambling that distorted object shape. Neural shape sensitivity was assessed by measuring the reduction of fMRI activation in response to scrambled versus intact versions of the same stimulus. In the ventral pathway, shape sensitivity increased linearly along an anterior-posterior axis from early visual cortices (i.e., v1-v4) to posterior extrastriate cortices (i.e., LO1) and remained constant along the occipitotemporal cortex. In the dorsal pathway, shape sensitivity also increased linearly along an anterior-posterior axis from early visual cortices (i.e., v1-v3d) to posterior extrastriate cortices (i.e., V3a, posterior IPS). However, in stark contrast to the ventral stream, in moving from posterior extrastriate cortices to more anterior regions (i.e., IPS 1-4, aIPS), shape selectivity gradually decreased. Interestingly, as with the anterior ventral pathway, the posterior IPS activation profile was found to be highly correlated with recognition performance obtained outside of the scanner, further pointing to a plausible contribution of this region to perception. Finally, these results were replicated using a different method for manipulating object integrity (diffeomorphic alteration) suggesting the results are not attributable to modulations of low-level object features. Together, these results provide novel evidence that object representations along the dorsal pathway are not monolithic and gradually change along the posterior-anterior axis. These findings challenge the binary dichotomy between the two pathways and suggest that object recognition might be the product of more distributed neural mechanisms. Meeting abstract presented at VSS 2017
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 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".