Modulation of the contrast response function of V1 neurons by the pulvinar
Bibliographic record
Abstract
Purpose The pulvinar establishes reciprocal connections with nearly all the visual cortices and is thus in a strategic position to influence analyses taking place at the cortical level. Projections from the pulvinar to the primary visual cortex (V1) are considered to be modulatory, altering decoding properties of neurons without changing their basic receptive field properties. Results from our laboratory, based on optical imaging, have supported this assumption (Soc. Neurosci. Abst. 2011. Vanni et al.). Methods Here, we investigate further by studying V1 single unit responses during reversible deactivation of the lateral posterior (LP) – pulvinar complex in the cat through microinjections of gamma‐aminobutyric acid. Recording and injection electrodes were positioned to obtain overlapping thalamic and cortical receptive fields. Results No change in the preferred orientation or direction selectivity of V1 neurons was observed during pulvinar deactivation. However, for 67% of the cells tested (n = 39/58), the response amplitude to the optimal stimulus was reduced by a mean of 65%. The contrast response function of neurons was modeled with the Naka‐Rushton function and analysis of the effects of pulvinar deactivation revealed at least three types of modulation based on the function parameter predominantly affected: 24% of cells had a decrease in Rmax, 13% had an increase in the exponential factor and 11% had a C50 increase. Conclusions Our results suggest that the pulvinar modulates activity of neurons in the primary visual cortex in a contrast‐dependent manner. Consequently, this extrageniculate nucleus is likely to contribute to cortical processing in shaping spatiotemporal activity patterns of V1 neurons.
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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".