Optimal stimulus size maps in the primary visual cortex revealed by optical imaging in cats
Bibliographic record
Abstract
Abstract Purpose: It is well known that the responses of cells in the primary visual cortex depend on stimulus size. While the stimulus‐size dependency has been well documented at the cellular level, nothing is known about its consequences on global functional maps. Methods: Optical imaging of intrinsic signals in the primary visual cortex was carried out in anesthetized cats. Stimuli consisted of 0.75 to 0.1 cycles per degree square‐wave gratings drifting in 8 directions at 2 to 4 Hz and were presented monocularly. Responses were obtained for different stimulus diameters (3 to 50 deg, and a full screen condition). Results: The minimal visual stimulation necessary to activate areas 17 and 18 was around 3 and 6 deg. in diameter respectively. The activation area of cortex (10‐30 mm2) was dependent of the eccentricity (0 to 30 deg). The pixelwise measure of the signal magnitude in this area showed a modular organisation uncorrelated with the orientation map and stable in time: Half of the pixels had a maximum activation for the full screen stimulation (full field facilitation) and the other half attained their maximum for diameters about 15 and 30 deg of diameter in area 17 and 18 respectively (full field suppression). The suppression by the full screen stimulation was around 30% in both areas. Conclusions: Thus, the maximum activation revealed by optical imaging necessitates the stimulation of a much larger spatial area than that observed with single cells. This difference is likely due to the fact that this method reflects in‐ and out going signals and reveals activity of adjacent neurons being part of intra‐cortical and thalamo‐cortical circuits. Supp: NSERC and CIHR.
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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 | 0.000 |
| 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 | 0.000 |
| 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".