Visual cortex responses to visual and electrical stimulations recorded by voltage sensitive dye imaging in cats and tree shrews
Bibliographic record
Abstract
It is well known that the primary visual cortex received its main thalamic drive from the lateral geniculate nucleus (LGN) through layer IV. In contrast, projections from the lateral posterior (LP) -pulvinar complex end for the most part in layer I, suggesting that LP-pulvinar exerts a diffuse modulatory influence on activity of the primary visual cortex. If that is the case, one would expect the spatio-temporal responses evoked by activation of these two pathways to be different. We investigated this issue by measuring the spatiotemporal dynamics of voltage sensitive dyes activation in the visual cortex following thalamic electrical stimulation in two different species: cats and tree shrews. Responses were compared to those evoked by visual stimuli (flashing squares and drifting gratings). Animals were anesthetized with halothane. RH1691 dye was used to stain the cortex. Stimulating electrodes were placed in the LGN and LP-pulvinar complex. Cortical responses evoked by flashing squares were observed in regions extending to several millimeters. At the activation site, positive responses were maximal at 90 ms, while in surrounding regions, negatives responses were observed (followed by activation). In cats, this profile was observed at the onset and offset of the square, while in tree shrew, it was only for the stimulus appearance. For gratings, orientation selectivity exhibited a tonic profile in cats, but a more transient one in tree shrews. Electrical stimulation of LGN induced a complex response comprising a fast positive component followed by a slow biphasic one. In surrounding and contralateral cortices, negative responses were observed, followed by activation. Electric stimulation of pulvinar did not induce any responses but strongly reduced the slow LGN-induced biphasic responses. In conclusion, stimulus inputs induce complex (species-selective) mechanisms of excitation/inhibition in time and space which involve cortical networks as well as thalamic modulation.
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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".