Texture-modulation channels for spatial frequency and orientation
Bibliographic record
Abstract
Second-order orientation-modulated stimuli are thought to be processed by a two stages mechanism : the first, processing the carrier in striate cortex and the second, processing the modulation in extra-striate cortex. Much is known about the spatial properties of the mechanisms underlying carrier detection however little is known about the properties of the mechanisms involved in modulation detection and integration of carrier-based information. Here we propose to investigate the properties of spatial channels underlying this detection of second-order texture-modulations. For this purpose, we chose to use a discrimination at detection paradigm, implemented by a two-by-two alternative forced choice (2x2AFC) protocol. This protocol allows a normalized indicator of the performance, thus comparable across sessions and subjects and a perfect discrimination test. We show that the mechanisms underlying modulation detection are tuned for relative modulator spatial frequency and orientation, namely channels of about 1-2 octaves for spatial frequency and 30° for orientation. This tuning is not substantially different from that previously described for carrier mechanisms. Furthermore, for orientation, these stimuli exhibit an oblique effect which could be modulated by carrier orientation, suggesting facilitative interactions between first and second stage processes. To conclude, these observations suggest sub-mechanisms tuned for modulation orientation that are similar in their tuning to that previously reported for 1st order, luminance-defined stimuli. They also support a model of two mixed processing stages, one for carrier and one for modulator and highlights the need to better understand the types of interactions that occur between 1st and 2nd order processes, probably at different stages in ventral and dorsal pathways. In a near future, we will investigate these physiological aspect by modulating cortical excitability with repetitive transcranial magnetic stimulation (rTMS). Meeting abstract presented at VSS 2012
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".