Independent Influence of Luminance and Color on Saccade Initiation During Target Selection In the Superior Colliculus
Bibliographic record
Abstract
One of the main functions of the superior colliculus (SC) is to orient visuospatial attention towards behaviorally relevant stimuli on the basis of visual features such as color. However a longstanding view has held that visual activity in the SC arises exclusively from achromatic pathways. Recently we (White et al., 2009) reported evidence that the SC also receives a significant contribution from chromatic pathways, supported by the fact that the arrival time for color was significantly delayed relative to luminance. Here we explored consequences of this shift in visual arrival time on target selection processes in the SC. Monkeys were trained to perform a color-oddball search task under three conditions: 1) Isoluminance-easy (“pink” target amongst “yellow” distractors, isoluminant with the background), 2) Luminance-easy (luminance pedestal added to all items), and 3) Isoluminant-difficult (distractor chromaticity shifted closer to target chromaticity). These conditions allowed us to formulate predictions based on three parameters, visual response onset latency (ROL), neural discrimination time (DT), and saccadic reaction time (SRT). We predicted longer SRTs in the isoluminance-easy relative to the luminance-easy condition because of the delay in ROL for the former. In contrast, we predicted longer SRTs in the isoluminance-difficult relative to the isoluminance-easy condition because of reduced target-distractor discriminability for the former. Results showed that SRTs were prolonged in the isoluminance-easy relative to the luminance-easy condition due to the delay in ROL, while DT remained relatively fixed. In contrast, SRTs were prolonged in the isoluminance-difficult relative to the isoluminance-easy condition due to prolonged DT, while ROL remained fixed. The results support the idea that during search for a color singleton, task irrelevant luminance signals associated with the stimuli can directly trigger the accumulation of SC neuronal activity towards response threshold independent and in advance of the arrival of the task-relevant color component of the stimuli.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".